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Article

In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution

by
Dominika Święch
1,*,
Natalia Piergies
2,
Gaetano Palumbo
1 and
Czesława Paluszkiewicz
2
1
Faculty of Foundry Engineering, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland
2
Institute of Nuclear Physics Polish Academy of Sciences, 31-342 Krakow, Poland
*
Author to whom correspondence should be addressed.
Coatings 2023, 13(1), 175; https://doi.org/10.3390/coatings13010175
Submission received: 9 December 2022 / Revised: 5 January 2023 / Accepted: 9 January 2023 / Published: 12 January 2023
(This article belongs to the Special Issue Novel Approaches on the Coatings Materials: Biomedical and Industrial Applications)
Browse Figures
Versions Notes

Abstract

:
In this paper, surface-enhanced Raman spectroscopy (SERS) was used to investigate the adsorption process of cysteine (Cys). Studies were carried out in the presence of phosphate-buffered saline solution (PBS), at pH 7.4, and acidified to pH 5, 3, and 1, on the surface of Ti for implant application. In situ SERS spectra obtained for the Cys/Ti solution system, after 24 h of immersion time, indicated that the buffer solution strongly influences the adsorption behavior of Cys on the Ti surface. This results in a decrease in Cys adsorption on the Ti surface, in the range of pH 7.4 to 3. The strong interaction between a sulfur atom of Cys and a Ti surface was observed only at pH = 1, under strongly acidic conditions. In contrast, ex situ SERS spectra recorded for the same samples but in a dried Cys/Ti system show a completely different behavior of Cys on the Ti surface. Formation of a disulfide (S-S) bond has occurred as a result of the dimerization or aggregation of Cys molecules on the Ti surface. Detailed analysis of the adsorption behavior of Cys on the Ti surface can be very important in the preparation of bioactive materials (i.e., coated by organic layers).

Graphical Abstract

1. Introduction

Cysteine (Cys) is a sulfur-containing endogenous amino acid that acts in a wide range of biological functions, i.e., protein synthesis, enzyme structure, detoxification cellular systems, and metabolism [1,2]. It is a metabolic precursor for cystine (thiol groups (SH) of two Cys molecules form a disulfide bond (S–S)), glutathione (γ-glutamyl–cysteinyl–glycine) [2,3]. The concentration gives important information about the physiological functions of the human body, it can be an indicator of health conditions [4]. Both deficiencies and high concentrations of this plasma amino acid are harmful and can contribute to various diseases such as edema, liver damage and Alzheimer’s disease, respectively [1,4,5,6]. Cys has many important applications in cosmetic, pharmaceutical, and food branches of industries such as antioxidants and medicine [7,8].
In addition, Cys is a popular stabilization agent for metallic structures [9]. The Cys-protected structure presents good optical properties and biocompatibility for biomedical applications [10,11], as well as in the area of studies of protein interactions with metallic nanostructures [12]. A wide range of experimental and theoretical studies have shown that Cys is strongly adsorbed onto different metal surfaces, such as Ag [9], Au [9,13], Cu [9], and metal oxides, i.e., TiO2 [14,15,16].
Commercially, pure titanium (Ti; grades 1–4) and its alloys are widely used for medical applications, such as orthopedic devices [17], and dental implants [18], due to their very good biocompatibility, chemical stability, and mechanical properties [19]. Titanium has excellent corrosion resistance due to the oxide layer formed (mainly TiO2) on its surface [19,20].
The adsorption of proteins on implanted materials is regarded as the first biologic response that occurs after implantation. The metallic surface of the biomaterial is coated with proteins from the surrounding environment and forms a variable protein layer [21,22]. It is a very complex process, which depends on many parameters such as roughness, hydrophobicity/hydrophilicity of the surface, protein molecular structure (i.e., amino acid chain, charge), and solution (pH, concentration, temperature) [22]. Cys is the amino acid that is present in many plasma proteins, for example, serum albumin, which has a high Cys content [23]. Additionally, thiol groups can be used for protein immobilization due to the formation of disulfide bonds with Cys amino acids [24]. Furthermore, the very important aspect that appears after implantation is the decrease of local pH around the biomaterials, which is caused by surrounding it with, i.e., chloride ions [25]. In addition, the bacterial colonization and adhesion of bacterial biofilms provide pH alterations and create a localized acidic condition, causing damage to the surface oxidation layer of metallic implants [26]. The application of oral drugs (acidic chemicals) can strongly influence Ti dental implants due to changes that occur in the implant environments [27].
Raman spectroscopy is a great tool for investigating the molecular structure of various species in a wide variety of applications [28,29]. It is quick, non-destructive, and insensitive to the water method. Raman spectra give a fingerprint of a molecule and can be analyzed for molecules in different states [30,31]. Raman scattering can be drastically enhanced for molecules adsorbed or in close proximity to the metallic surface, resulting in a very sensitive surface-enhanced Raman spectroscopy technique [32,33,34,35,36]. Vibration fingerprints depend on many parameters, i.e., that is, the molecular environment (pH of the buffer solution) [37,38] and properties of the metallic surface [39]. This sensitive technique has been used in many in situ studies to determine the composition of different adsorbate layers in an aqueous solution [36]. The greatest enhancement factor can be obtained for noble metals such as Ag, and Au [9]. The SERS signal intensities obtained on Ti structures (TiO2 surfaces), compared to the above-mentioned metals, are rather lower [40].
In the present paper, we applied in situ SERS spectroscopy to monitor the Cys behavior on the Ti surface in real-time, after 24 h of immersion in the solution of PBS, at pH 7.4 (physiological conditions), and in the acidic solution at pH 5, 3, and 1. To better understand the adsorption behavior of Cys on the Ti surface, ex situ SERS spectroscopy measurements obtained for dried samples in the same conditions were provided. Despite the many investigations conducted on biomolecules immobilized on different metallic surfaces [33,34,35,41], there is still a lack of studies in this area. Detailed analysis of the adsorption process of Cys on the Ti surface, in the presence of buffer solution, in a different state, under control conditions, can be very important in the preparation of bioactive materials (i.e., coated by organic layers).

2. Materials and Methods

The samples were prepared from a Ti grade 2 sheet (Wolften, Wrocław, Poland) (chemical analysis: 0.02% C; 0.002% H; 0.05% Fe; 0.12% O; balance Ti). Samples were machined with dimensions of 200 mm × 200 mm × 2 mm. After that, the samples were polished with silicon carbide papers up to a 2400 grit finish. The surface of Ti was then washed with deionized water and ultrasonically cleaned for 20 min in ethanol.
Cys (Cys, 10−1 M, Sigma Aldrich, Poznań, Poland) reference Raman spectra in PBS (Sigma Aldrich, Poland) solutions at pH 7.4, 5, 3, and 1 and for the same dried samples were recorded. The pH value was adjusted by titration of HCl (analytical grade reagent) using a pH meter. The PBS composition of the solution at pH 7.4 was the following: 0.0027 M potassium chloride, 0.137 M sodium chloride and 0.01 M phosphate buffer.
The adsorption behavior of Cys (10−2 M) onto the Ti surface was investigated in PBS solution at pH 7.4, 5, 3, and 1. In situ SERS measurements were recorded after 24 h of immersion of Ti samples in Cys solution at controlled pH. Ex situ SERS measurements were performed for samples prepared under the same conditions as described above, but in a dried system (drying temperature 37 °C).
An InVia Renishaw Raman spectrometer (Renishaw, Wotton-under-Edge, UK) with a CCD camera and a confocal microscope was applied to measure Raman scattering. The excitation wavelength was provided by the laser emitting at 633 nm (mode Regular) with 1800 grooves/mm grating. The output power of the laser at the sample was set at approximately 5 mW. The spectra presented were collected with a spectral resolution of 1 cm−1 and in the spectral range of 1530 to 360 cm−1. The in situ spectra maps were collected with a 1 µm step size (2640 acquisitions, exposure time 1 s, laser power 5 mW, spectral range 1530–400 cm−1). The 100-lens long Leica objective was used. The ex situ spectra were recorded by the same Raman system from 8 different points of the sample (spectral resolution 1 cm−1, 1 scan, exposure time 10 s, laser power 5 mW, spectral range 1530–400 cm−1).
Interpretation and analysis of the recorded spectra were performed using the OMNIC (9.0 version) and WIRE 5.2 software.

3. Results and Discussion

3.1. In Situ Raman Measurements

The reference Raman spectra recorded for the solution of Cys (10−1 M/PBS) at pH = 1, 3, 5, and 7.4 are shown in Figure 1A. The proposed band assignments were based on experimental and theoretical vibrational data from the literature on the molecular structure of free Cys [31,42,43,44] in different states and adsorbed on different metallic surfaces, such as Au, Ag, Cu [9,13,39,45,46], FeS2 [47] and TiO2 [14,15,16]. Table 1 presents the wavenumber and band assignments of characteristic vibrational modes of the investigated samples. It should be noted that the preparation of samples for measurements has a significant impact on the spectral information obtained. Parameters such as the sample’s condition [35], type of solvent [48], buffer solutions [49], and pH [30,33,50] can influence the recorded spectra.
The reference Raman spectra for Cys (10−1 M/PBS) were obtained in solution at a pH from 1 to 7.4 and do not differ significantly from each other. However, a slight shift between the wavenumbers of bands is observed, i.e., at ~1430 cm−1, ~1399 cm−1, ~1348 cm−1, ~875 cm−1, ~681 cm−1 upon pH changes (see Table 1 for appropriate bands assigned). At pH = 1 (below pKa1 = 1.96) the Cys is positively charged, due to the amine group (NH3+). At a pH higher than pKa1 and lower than pKa2 (pKa2 = 8.18), in the case of Raman spectra obtained at pH = 3, 5, and 7.4, Cys exists in the zwitterionic form (COO−/NH3+) [16].
The Raman spectra of free Cys are dominated by characteristic modes due to molecular fragments of CS, COO, NH3+, and CN/CH (see Table 1 for detailed assignments). The most intense band (the comparable relative intensity among the spectrum) appeared at ~681 cm−1 (full-width at half-maximum, fwhm = 23 cm−1) and is characteristic of the CβS stretching bond. Another band at ~774 cm−1 is due to thiol bending vibration modes. In Raman spectra, in the region between ~1500 cm−1 and ~1200 cm−1, the main carboxyl symmetric stretching bands of free Cys are located (see Table 1, for appropriate band assignments). The bands in the wavenumber range between ~1200 cm−1 and ~800 cm−1 can be assigned to the vibration bands of amine (~875 cm−1 (NH3+ rocking)) and CN (~1211 cm−1 (HCN bending),~1074 cm−1 (CαN stretching), ~1001 cm−1 (NCH stretching), ~936 cm−1 (HCN bending)) vibration bands (see Table 1) [9,37].
The in situ SERS spectrum obtained for a Cys (10−2 M) sample at pH 1.0 in solution adsorbed onto the Ti surface obtained after 24 h of exposure presents significant differences in the relative intensity, position, and width of wavenumber corresponding to the Raman of the non-adsorbed Cys. The largest change in the SERS spectrum for Cys adsorbed on the Ti surface (solution/pH = 1) is the appearance of the strong CβS stretching band at 660 cm−1. The position of this band is sensitive to the torsion angle N-CαCβS and provides information about the rotational configuration of the Cys during adsorption onto the metallic surface, as reported by Yao and Hang [13] and Rodríguez-Zamora et al. [9,45]. This spectral characteristic shows a greater enhancement, a significant red-shift (Δῡ = 21 cm−1), and a broadening (Δfwhm = 22 cm−1) compared to those observed in the Raman spectrum of the free Cys (Figure 1A). Spectral data reported for different metallic structures (Ag, Au, Cu) indicated that the red-shift of the CβS stretching band of Cys confirms a structural modification of the molecular structure of the amino acid in the adsorption process [9,46]. It can be suggested that Cys (solution/pH =1) strongly interacted with the surface of Ti via the thiol group.
Figure 2A shows the map of the distribution of the CβS stretching band at 660 cm−1 on the Ti surface and selected in situ SERS spectra recorded from three different positions (Figure 2B). The obtained map of the distribution of the Cys on the Ti’s surface confirms the strong Cys adsorption on the metallic surface. In a strongly acidic environment (pH = 1), the cationic form of Cys is the predominant species. Under these conditions, the protonated form of Cys can electrostatically adsorb onto the chloride-covered metallic surface. The chloride ions can promote the physical adsorption of cations on the metallic surface and, in addition, the Cys molecules can be adsorbed on the metallic surface due to the formation of linkage between the lone pair of electrons of the S atom and the Ti surface.
In the case of Cys, the existence of three different isomeric configuration forms is possible, allowing for three conformations due to its torsion angle (N-CαCβS) [9,13,45]. The above-mentioned isomeric rotational conformers/rotamers are named by the atom or functional group that is in antiposition the SH group (PN: the amine (NH3+) group in the antiposition and the COO group in the gauche position; PH—the hydrogen (H) atom is in the antiposition and COO and NH3+ groups are in the gauche position; Pc—COO group in the antiposition and NH3+ group in the gauche position) [9,13,45].
The CβS stretching band for the PN conformer is located at a higher wavenumber (as proposed by Yao and Huang [13]) than for the PC and PH conformers. Based on these data, the position of the CβS band at 660 cm−1 excluded the formation of the PN conformer during the adsorption of Cys on the Ti surface in the solution state. The blue-shift of a band at 889 cm−1 due to NH3+ rocking and NCα stretching vibration compared to free Cys (see Figure 1A) can be explained as the reduction of the N-CαCβS dihedral angle during the adsorption process of Cys molecule on the Ti surface, followed by Rodríguez-Zamora et al. [9]. This observation indicates that the NH3+ group is close to the negatively charged metallic surface (high concentration of chloride anions on the Ti surface), but it does not adsorb directly on the metallic surface. Furthermore, the significant reduction in the relative intensity of characteristic bands due to the COO symmetric stretching band appearing at 1402 cm−1 compared to the Raman spectrum of Cys indicated that this molecular fragment is at some distance from the Ti surface. Based on these spectral changes, it can be proposed that Cys at pH = 1 in solution is adsorbed mainly by the sulfur atom with the carboxyl group some distance from the Ti surface under acidic conditions. We can suggest that the Cys conformer that stabilizes on the Ti surface is mainly PC (COO group in antiposition with respect to the S atom). Figure 3 shows the proposed adsorption process of Cys in the solution on the Ti surface at pH = 1.
For in situ SERS spectra obtained for the sample immersed in the presence of Cys and PBS solution at pH 3, 5, and 7.4 in PBS solution (see Figure 1B), the characteristic bands due to Cys are not enhanced, or very weak. The characteristic band at 660 cm−1 is not enhanced. The in situ SERS spectra (Figure 1B) obtained under these conditions drastically differ from the respective reference Raman spectra of Cys at the same pH (Figure 1A). At pH 3, 5, and 7.4 the appearance of bands at ~1175 cm−1 and ~1056 cm−1 can be mainly assigned to vibrations due to phosphate groups from the buffer solution [49,51,52]. Moulton et. al. [51] and Loreto et al. [52] have studied the influence of PBS on the adsorption behavior of different proteins (immunoglobulin, myoglobin) on TiO2 films and reported that the buffer is strongly adsorbed on the metallic surface. They proposed that the use of PBS has an influence on the adsorption process and can inhibit the adsorption of proteins. In addition, Wang et al. [49] proposed that SERS substrates immersed in PBS solutions were found to be unstable in low buffer solutions (pH = 3) and neutral pH (=7). In the case of our system, the drastic weakness of the bands due to the molecular Cys species in the range of pH from 3 to 7.4, together with the appearance of bands of phosphate anions, can confirm this statement. The buffer species interacted with the Ti surface, leading to a competing interaction with the Ti surface, as has also been reported by Loreto et al. on commercial mesoporous TiO2 [52].

3.2. Ex Situ Raman Measurements

Figure 4A presents the Raman spectra obtained for dried samples of Cys (10−1 M/PBS/pH 1, 3, 5, and 7.4). As was claimed in Chapter 3.1., the preparation of the sample strongly influences the obtained spectral information. The Raman spectra for Cys obtained in the solid state (Figure 4A) differ from those obtained in the solution state (Figure 1A). The most intense band due to the CβS stretching bond appeared at 639 cm−1 (fwhm = 10 cm−1); in the solution state, this band has been red-shifted and appears at ~681 cm−1. These Raman spectra, similar to the Raman spectra obtained in the solution system, only slightly differ in the pH range from 1 to 7.4. The most important difference in the spectral pattern appears at pH 7.4; in the Raman spectrum, we observed band at 498 cm−1, which can be assigned to the stretching vibration of the disulfide (S-S) bond [42]. The appearance of this spectral band can suggest that the dimerization or aggregation of Cys is occurring at neutral pH [39,42,53].
The SERS spectra obtained for dried samples of Cys (10−2 M/PBS) at pH of 1 to 7.4 adsorbed on the Ti surface show significant differences in the relative intensity, position and width of the wavenumber corresponding to the Raman spectra of free Cys.
As mentioned above (see Section 3.1.), the position of the band due to the CβS molecular species of Cys is very sensitive to conformational changes of the molecule and gives key information about the adsorbate behavior on the metallic surface. In the SERS spectrum obtained for Cys, adsorbed on the Ti surface in an acidic medium (pH = 1), the reduction in relative intensity, slight red-shift (Δῡ = 4 cm−1), and broadening (Δfwhm = 7 cm−1) of the band at 635 cm−1 (CβS bond) compared to the Raman spectrum suggest that the sulfur atom is adsorbed on the Ti surface. Upon increase of pH, at pH = 3, 5, and 7.4, a weakening of the relative intensity of the CβS band is also observed compared to the normal Raman spectra. However, unlike pH = 1, as the pH increases, there is a significant blue-shift (ΔῡpH=3 = 37 cm−1; ΔῡpH=5 = 41 cm−1, and ΔῡpH=7.4 = 33 cm−1) of this band. These spectral changes can suggest the rearrangement of adsorbate molecules on the Ti surface.
Furthermore, the appearance of a band at 496 cm−1 (see Figure 4B, pH = 1), characteristic of the disulfide (S-S) bond, may indicate that the Cys molecules undergo dimerization upon adsorption on the Ti surface, resulting in cystine formation [42]. Jing and Fang [39] proposed that the Ag surface activated by the co-adsorption of Cl− anions provided the formation of cystine molecules. Furthermore, Rodríguez-Zamora et al. [9] suggested that adsorbed Cys on the Ag surface propitiated the formation of the stretching vibration belonging to the S-S bond. The dimerization of some Cys molecules was also observed by Marti et al. [54] upon adsorption on the Cu surface. Upon an increase in pH, the strengthened relative intensity of the band at 497 cm−1 (Figure 4B) indicates that the formation of the Cys dimer on the Ti surface cannot be excluded. The increase in pH enhances the dimerization of Cys, as claimed by Shkirskiy et al. [55].
Based on the changes in vibration modes that occur at ~1390 cm−1 and ~1341 cm−1 upon the Cys adsorption process on the Ti surface (Figure 4B, pH = 3–7.4) relative to the ordinary Raman spectra, it can be suggested that the COO group or groups (the formation of cystine) are also at some distance from the metallic surface. These bands are blue-shifted compared to those observed in the normal Raman spectrum (see Figure 4A). As was claimed by i.e., Rodríguez-Zamora et al. [9] and López-Tobar et al. [56], the above-mentioned changes of spectral patterns can indicate that carboxyl groups assist in the adsorption process of Cys/cystine on the Ti surface.
The proposed orientation of the investigated molecule on the Ti surface in the dried system is presented in Figure 5. An interaction occurring via S-S bonds being tilted to the Ti surface and interacting via lone pair of electrons without disulfide bridge cleavage can be suggested.

4. Conclusions

In this work, the adsorption behavior of Cys in two different systems is presented. Raman spectroscopy was applied to obtain information about Cys at different pH levels (from pH = 7.4 to pH = 1, acidified by HCl), in the presence of PBS solutions on the Ti surface. The reference Raman spectra for free Cys were recorded under the same conditions.
In situ SERS spectra for Cys (10−2 M) obtained after 24 h of exposure time in an acid solution (pH = 1) on the surface of Ti indicated that the amino acid was strongly adsorbed mainly through an electron pair of the sulfur atom. Upon an increase of pH, from pH 3 to 7.4, after 24 h of exposure, the presence of the PBS solution in the investigated system drastically decreases the adsorption of Cys on the Ti surface. These findings are visible through weakening of the bands due to Cys groups, together with enhancements of the spectral signal from phosphate anions.
The ex situ SERS results, which were obtained for the same samples but in a dried system, present a completely different spectral response. The appearance of the strong band due to the disulfide (S-S) bond suggested that Cys undergoes dimerization to cystine and interacts with the Ti surface. The comparison of in situ and ex situ spectroscopic results gives new information about amino acid behavior on the Ti surface under controlled conditions.

Author Contributions

D.Ś. conceptualization, vibrational spectroscopic measurements, data analysis, writing—original draft preparation and editing, visualization, funding acquisition, project administration; G.P. contributed to the final version of the manuscript, N.P. contributed to the final version of the manuscript; C.P. contributed to the final version of the manuscript. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Science Centre, Poland, grant number 2019/35/D/ST4/02703 and AGH University, number of statutory project 16.16.170.654. The research was partly performed using the equipment purchased in the frame of the project co-funded by the Małopolska Regional Operational Program Measure 5.1 Krakow Metropolitan Area as an important hub of the European Research Area for 2007–2013, project no. MRPO.05.01.00-12-013/15.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Takagi, H.; Ohtsu, I. l-Cysteine metabolism and fermentation in microorganisms. In Amino Acid Fermentation; Yokota, A., Ikeda, M., Eds.; Springer: Tokyo, Japan, 2017; pp. 129–151. [Google Scholar]
  2. Courtney-Martin, G.; Pencharz, P.B. Chapter 19—Sulfur amino acids metabolism from protein synthesis to glutathione. In The Molecular Nutrition of Amino Acids and Proteins; Dardevet, D., Ed.; Academic Press: Boston, MA, USA, 2016; pp. 265–286. [Google Scholar]
  3. Lomont, J.P.; Smith, J.P. In situ Raman spectroscopy for real time detection of cysteine. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2022, 274, 121068. [Google Scholar] [CrossRef] [PubMed]
  4. Rehman, T.; Shabbir, M.A.; Inam-Ur-Raheem, M.; Manzoor, M.F. Cysteine and homocysteine as biomarker of various diseases. Food Sci. Nutr. 2020, 8, 4696–4707. [Google Scholar] [CrossRef] [PubMed]
  5. Kurniawan, A.; Kurniawan, F.; Gunawan, F.; Chou, S.-H.; Wang, M.-J. Disposable electrochemical sensor based on copper-electrodeposited screen-printed gold electrode and its application in sensing l-Cysteine. Electrochim. Acta 2019, 293, 318–327. [Google Scholar] [CrossRef]
  6. Hasanbasic, S.; Jahic, A.; Karahmet, E.; Sejranic, A.; Prnjavorac, B. The role of cysteine protease in Alzheimer disease. Materia socio-Medica 2016, 28, 235–238. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  7. Imura, M.; Etoh, S.; Iwakiri, R.; Okano, K.; Honda, K. Improvement of production yield of l-cysteine through in vitro metabolic pathway with thermophilic enzymes. J. Biosci. Bioeng. 2021, 132, 585–591. [Google Scholar] [CrossRef]
  8. Clemente Plaza, N.; Reig García-Galbis, M.; Martínez-Espinosa, R.M. Effects of the usage of l-Cysteine (l-Cys) on human health. Molecules 2018, 23, 575. [Google Scholar] [CrossRef] [Green Version]
  9. Rodríguez-Zamora, P.; Cordero-Silis, C.A.; Fabila, J.; Luque-Ceballos, J.C.; Buendía, F.; Heredia-Barbero, A.; Garzón, I.L. Interaction mechanisms and interface configuration of cysteine adsorbed on gold, silver, and copper nanoparticles. Langmuir 2022, 38, 5418–5427. [Google Scholar] [CrossRef]
  10. Yang, X.; Feng, Y.; Zhu, S.; Luo, Y.; Zhuo, Y.; Dou, Y. One-step synthesis and applications of fluorescent Cu nanoclusters stabilized by l-cysteine in aqueous solution. Anal. Chim. Acta 2014, 847, 49–54. [Google Scholar] [CrossRef]
  11. Perni, S.; Hakala, V.; Prokopovich, P. Biogenic synthesis of antimicrobial silver nanoparticles capped with l-cysteine. Colloids Surf. A Physicochem. Eng. Asp. 2014, 460, 219–224. [Google Scholar] [CrossRef]
  12. Awotunde, O.; Okyem, S.; Chikoti, R.; Driskell, J.D. Role of free thiol on protein adsorption to gold nanoparticles. Langmuir 2020, 36, 9241–9249. [Google Scholar] [CrossRef]
  13. Yao, G.; Huang, Q. DFT and SERS study of l-cysteine adsorption on the surface of gold nanoparticles. J. Phys. Chem. C 2018, 122, 15241–15251. [Google Scholar] [CrossRef]
  14. Ataman, E.; Isvoranu, C.; Knudsen, J.; Schulte, K.; Andersen, J.N.; Schnadt, J. Adsorption of L-cysteine on rutile TiO2 (110). Surf. Sci. 2011, 605, 179–186. [Google Scholar] [CrossRef]
  15. Muir, J.M.R.; Idriss, H. Computational study of cysteine interaction with the rutile TiO2 (110) surface. Surf. Sci. 2013, 617, 60–67. [Google Scholar] [CrossRef]
  16. Begonja, S.; Rodenas, L.A.G.; Borghi, E.B.; Morando, P.J. Adsorption of cysteine on TiO2 at different pH values: Surface complexes characterization by FTIR-ATR and Langmuir isotherms analysis. Colloids Surf. A Physicochem. Eng. Asp. 2012, 403, 114–120. [Google Scholar] [CrossRef]
  17. Quinn, J.; McFadden, R.; Chan, C.-W.; Carson, L. Titanium for orthopedic applications: An overview of surface modification to improve biocompatibility and prevent bacterial biofilm formation. iScience 2020, 23, 101745. [Google Scholar] [CrossRef]
  18. Xi, D.; Wong, L. Titanium and implantology: A review in dentistry. J. Biol. Regul. Homeost. Agents 2021, 35 (Suppl. 1), 63–72. [Google Scholar]
  19. Chen, Q.; Thouas, G.A. Metallic implant biomaterials. Mater. Sci. Eng. R Rep. 2015, 87, 1–57. [Google Scholar] [CrossRef]
  20. Li, X.-R.; Meng, X.-Z.; Zhang, Q.-H.; Cai, H.-R.; Yan, Z.-Z.; Wu, L.-K.; Cao, F.-H. In situ studies of hydrogen evolution kinetics on pure titanium surface: The effects of pre-reduction and dissolved oxygen. J. Phys. Chem. C 2022, 126, 1828–1844. [Google Scholar] [CrossRef]
  21. Souza, J.G.S.; Bertolini, M.M.; Costa, R.C.; Nagay, B.E.; Dongari-Bagtzoglou, A.; Barão, V.A.R. Targeting implant-associated infections: Titanium surface loaded with antimicrobial. iScience 2021, 24, 102008. [Google Scholar] [CrossRef]
  22. Barberi, J.; Spriano, S. Titanium and protein adsorption: An overview of mechanisms and effects of surface features. Materials 2021, 14, 1590. [Google Scholar] [CrossRef]
  23. Jing, P.P.; Li, Y.X.; Su, Y.H.; Liang, W.L.; Leng, Y.X. The role of metal ions in the behavior of bovine serum albumin molecules under physiological environment. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2022, 267, 120604. [Google Scholar] [CrossRef] [PubMed]
  24. Stewart, C.; Akhavan, B.; Wise, S.G.; Bilek, M.M.M. A review of biomimetic surface functionalization for bone-integrating orthopedic implants: Mechanisms, current approaches, and future directions. Prog. Mater. Sci. 2019, 106, 100588. [Google Scholar] [CrossRef]
  25. Talha, M.; Ma, Y.; Kumar, P.; Lin, Y.; Singh, A. Role of protein adsorption in the bio corrosion of metallic implants—A review. Colloids Surfaces B Biointerfaces 2019, 176, 494–506. [Google Scholar] [CrossRef] [PubMed]
  26. Sridhar, S.; Wang, F.; Wilson, T.G.; Palmer, K.; Valderrama, P.; Rodrigues, D.C. The role of bacterial biofilm and mechanical forces in modulating dental implant failures. J. Mech. Behav. Biomed. Mater. 2019, 92, 118–127. [Google Scholar] [CrossRef] [PubMed]
  27. Wheelis, S.E.; Gindri, I.M.; Valderrama, P.; Wilson, T.G., Jr.; Huang, J.; Rodrigues, D.C. Effects of decontamination solutions on the surface of titanium: Investigation of surface morphology, composition, and roughness. Clin. Oral Implant. Res. 2016, 27, 329–340. [Google Scholar] [CrossRef] [PubMed]
  28. Kuhar, N.; Sil, S.; Umapathy, S. Potential of Raman spectroscopic techniques to study proteins. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2021, 258, 119712. [Google Scholar] [CrossRef]
  29. Ekoi, E.J.; Gowen, A.; Dorrepaal, R.; Dowling, D.P. Characterisation of titanium oxide layers using Raman spectroscopy and optical profilometry: Influence of oxide properties. Results Phys. 2019, 12, 1574–1585. [Google Scholar] [CrossRef]
  30. Piergies, N.; Oćwieja, M.; Paluszkiewicz, C.; Kwiatek, W.M. Spectroscopic insights into the effect of pH, temperature, and stabilizer on erlotinib adsorption behavior onto Ag nanosurface. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2020, 228, 117737. [Google Scholar] [CrossRef]
  31. Hernández, B.; Pflüger, F.; Adenier, A.; Kruglik, S.G.; Ghomi, M. Side chain flexibility and protonation states of sulfur atom containing amino acids. Phys. Chem. Chem. Phys. 2011, 13, 17284–17294. [Google Scholar] [CrossRef]
  32. Plou, J.; Valera, P.S.; García, I.; de Albuquerque, C.D.L.; Carracedo, A.; Liz-Marzán, L.M. Prospects of surface-enhanced Raman spectroscopy for biomarker monitoring toward precision medicine. ACS Photonics 2022, 9, 333–350. [Google Scholar] [CrossRef]
  33. Święch, D.; Palumbo, G.; Piergies, N.; Pięta, E.; Szkudlarek, A.; Paluszkiewicz, C. Spectroscopic investigations of 316L stainless steel under simulated inflammatory conditions for implant applications: The effect of tryptophan as corrosion inhibitor/hydrophobicity marker. Coatings 2021, 11, 1097. [Google Scholar] [CrossRef]
  34. Piergies, N.; Oćwieja, M.; Paluszkiewicz, C.; Kwiatek, W.M. Nanoparticle stabilizer as a determining factor of the drug/gold surface interaction: SERS and AFM-SEIRA studies. Appl. Surf. Sci. 2021, 537, 147897. [Google Scholar] [CrossRef]
  35. Święch, D.; Palumbo, G.; Piergies, N.; Kollbek, K.; Marzec, M.; Szkudlarek, A.; Paluszkiewicz, C. Surface modification of Cu nanoparticles coated commercial titanium in the presence of tryptophan: Comprehensive electrochemical and spectroscopic investigations. Appl. Surf. Sci. 2023, 608, 155138. [Google Scholar] [CrossRef]
  36. D’Acunto, M. In situ surface-enhanced Raman spectroscopy of cellular components: Theory and experimental results. Materials 2019, 12, 1564. [Google Scholar] [CrossRef] [Green Version]
  37. Talley, C.E.; Jusinski, L.; Hollars, C.W.; Lane, S.M.; Huser, T. Intracellular pH sensors based on surface-enhanced raman scattering. Anal. Chem. 2004, 76, 7064–7068. [Google Scholar] [CrossRef]
  38. Bishnoi, S.W.; Rozell, C.J.; Levin, C.S.; Gheith, M.K.; Johnson, B.R.; Johnson, D.H.; Halas, N.J. All-optical nanoscale pH meter. Nano Lett. 2006, 6, 1687–1692. [Google Scholar] [CrossRef]
  39. Jing, C.; Fang, Y. Experimental (SERS) and theoretical (DFT) studies on the adsorption behaviors of l-cysteine on gold/silver nanoparticles. Chem. Phys. 2007, 332, 27–32. [Google Scholar] [CrossRef]
  40. Alessandri, I.; Lombardi, J.R. Enhanced Raman scattering with dielectrics. Chem. Rev. 2016, 116, 14921–14981. [Google Scholar] [CrossRef] [PubMed]
  41. Messina, E.; Giuliani, C.; Pascucci, M.; Riccucci, C.; Staccioli, M.P.; Albini, M.; Di Carlo, G. Synergistic inhibition effect of chitosan and L-cysteine for the protection of copper-based alloys against atmospheric chloride-induced indoor corrosion. Int. J. Mol. Sci. 2021, 22, 10321. [Google Scholar] [CrossRef] [PubMed]
  42. Diaz Fleming, G.; Finnerty, J.J.; Campos-Vallette, M.; Célis, F.; Aliaga, A.E.; Fredes, C.; Koch, R. Experimental and theoretical Raman and surface-enhanced Raman scattering study of cysteine. J. Raman Spectrosc. 2009, 40, 632–638. [Google Scholar] [CrossRef]
  43. Pawlukojć, A.; Leciejewicz, J.; Ramirez-Cuesta, A.J.; Nowicka-Scheibe, J. l-Cysteine: Neutron spectroscopy, Raman, IR and ab initio study. Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 2005, 61, 2474–2481. [Google Scholar] [CrossRef]
  44. Parker, S.F. Assignment of the vibrational spectrum of l-cysteine. Chem. Phys. 2013, 424, 75–79. [Google Scholar] [CrossRef]
  45. Rodríguez-Zamora, P.; Salazar-Angeles, B.; Buendía, F.; Cordero-Silis, C.; Fabila, J.; Bazán-Díaz, L.; Fernández-Díaz, L.M.; Paz-Borbón, L.O.; Díaz, G.; Garzón, I.L. Revisiting the conformational adsorption of L- and D-cysteine on Au nanoparticles by Raman spectroscopy. J. Raman Spectrosc. 2020, 51, 243–255. [Google Scholar] [CrossRef]
  46. Brolo, A.G.; Germain, P.; Hager, G. Investigation of the adsorption of l-cysteine on a polycrystalline silver electrode by surface-enhanced Raman scattering (SERS) and surface-enhanced second harmonic generation (SESHG). J. Phys. Chem. B 2002, 106, 5982–5987. [Google Scholar] [CrossRef]
  47. Suzuki, T.; Yano, T.-A.; Hara, M.; Ebisuzaki, T. Cysteine and cystine adsorption on FeS2 (100). Surf. Sci. 2018, 674, 6–12. [Google Scholar] [CrossRef]
  48. Costa, D.; Savio, L.; Pradier, C.M. Adsorption of amino acids and peptides on metal and oxide surfaces in water environment: A synthetic and prospective review. J. Phys. Chem. B 2016, 120, 7039–7052. [Google Scholar] [CrossRef]
  49. Wang, L.; Womiloju, A.A.; Höppener, C.; Schubert, U.S.; Hoeppener, S. On the stability of microwave-fabricated SERS substrates—Chemical and morphological considerations. Beilstein J. Nanotechnol. 2021, 12, 541–551. [Google Scholar] [CrossRef]
  50. Święch, D.; Paluszkiewicz, C.; Piergies, N.; Pięta, E.; Kollbek, K.; Kwiatek, W.M. Micro- and nanoscale spectroscopic investigations of threonine influence on the corrosion process of the modified Fe surface by Cu nanoparticles. Materials 2020, 13, 4482. [Google Scholar] [CrossRef]
  51. Moulton, S.E.; Barisci, J.N.; McQuillan, A.J.; Wallace, G.G. ATR-IR spectroscopic studies of the influence of phosphate buffer on adsorption of immunoglobulin G to TiO2. Colloids Surf. A Physicochem. Eng. Asp. 2003, 220, 159–167. [Google Scholar] [CrossRef]
  52. Loreto, S.; Cuypers, B.; Brokken, J.; Van Doorslaer, S.; De Wael, K.; Meynen, V. The effect of the buffer solution on the adsorption and stability of horse heart myoglobin on commercial mesoporous titanium dioxide: A matter of the right choice. Phys. Chem. Chem. Phys. 2017, 19, 13503–13514. [Google Scholar] [CrossRef] [Green Version]
  53. Brulé, T.; Yockell-Lelièvre, H.; Bouhélier, A.; Margueritat, J.; Markey, L.; Leray, A.; Dereux, A.; Finot, E. Sorting of enhanced reference Raman spectra of a single amino acid molecule. J. Phys. Chem. C 2014, 118, 17975–17982. [Google Scholar] [CrossRef]
  54. Mateo Marti, E.; Methivier, C.; Pradier, C.M. (S)-Cysteine chemisorption on Cu(110), from the gas or liquid phase:  An FT-RAIRS and XPS study. Langmuir 2004, 20, 10223–10230. [Google Scholar] [CrossRef] [PubMed]
  55. Shkirskiy, V.; Keil, P.; Hintze-Bruening, H.; Leroux, F.; Brisset, F.; Ogle, K.; Volovitch, P. The effects of l-cysteine on the inhibition and accelerated dissolution processes of zinc metal. Corros. Sci. 2015, 100, 101–112. [Google Scholar] [CrossRef]
  56. López-Tobar, E.; Hernández, B.; Ghomi, M.; Sanchez-Cortes, S. Stability of the disulfide bond in cystine adsorbed on silver and gold nanoparticles as evidenced by SERS data. J. Phys. Chem. C 2013, 117, 1531–1537. [Google Scholar] [CrossRef]
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Figure 1. Raman spectra of Cys (10−1 M/PBS) recorded at different pH in the solution state (A) and in situ SERS spectra of Cys (10−2 M/PBS) recorded at different pH, after 24 h of exposure to the Ti surface in the solution system (B).
Figure 1. Raman spectra of Cys (10−1 M/PBS) recorded at different pH in the solution state (A) and in situ SERS spectra of Cys (10−2 M/PBS) recorded at different pH, after 24 h of exposure to the Ti surface in the solution system (B).
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Figure 2. The intensity map of the SERS bands at 660 cm−1 (Cys (10−2 M/PBS, pH = 1.0) (A). In situ SERS spectra of Cys (10−2 M/PBS) recorded at pH = 1, after 24 h of exposure to the Ti surface in the solution system from points 1, 2, and 3, marked spots in A (B).
Figure 2. The intensity map of the SERS bands at 660 cm−1 (Cys (10−2 M/PBS, pH = 1.0) (A). In situ SERS spectra of Cys (10−2 M/PBS) recorded at pH = 1, after 24 h of exposure to the Ti surface in the solution system from points 1, 2, and 3, marked spots in A (B).
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Figure 3. Proposed adsorption behavior of Cys in the solution system on the Ti surface in an acidic environment (pH = 1).
Figure 3. Proposed adsorption behavior of Cys in the solution system on the Ti surface in an acidic environment (pH = 1).
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Figure 4. Raman spectra of Cys (10−1 M/PBS) recorded at different pH values in the solid state (A) and ex situ SERS spectra of Cys (10−2 M/PBS) recorded at different pH, after 24 h of exposure on the Ti surface in the dried system (B).
Figure 4. Raman spectra of Cys (10−1 M/PBS) recorded at different pH values in the solid state (A) and ex situ SERS spectra of Cys (10−2 M/PBS) recorded at different pH, after 24 h of exposure on the Ti surface in the dried system (B).
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Figure 5. Proposed adsorption behavior of the investigated molecule (Cys) in the dried system on the Ti surface.
Figure 5. Proposed adsorption behavior of the investigated molecule (Cys) in the dried system on the Ti surface.
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Table
Table 1. Proposed band assignments for Raman spectra for Cys in solution and solid states at pH =1, 3, 5, and 7.4 and recorded in the Cys/Ti in situ and ex situ system.
Table 1. Proposed band assignments for Raman spectra for Cys in solution and solid states at pH =1, 3, 5, and 7.4 and recorded in the Cys/Ti in situ and ex situ system.
Band
Assignments		pH = 1pH = 3pH = 5pH = 7.4
Raman Solution/Raman DriedIn-Situ SERS/Ex-Situ SERSRaman Solution/Raman DriedIn-Situ SERS/Ex-Situ SERSRaman Solution/Raman DriedIn-Situ SERS/Ex-Situ SERSRaman Solution/Raman DriedIn-Situ SERS/
Ex-Situ SERS
NH3+ bend.−/−1508/−−1495/−−1493/−−1493/−
CH2 bend.1430/1424−/−1427/1424−/−1430/1423−1428/1425−/−
COO sym. stretch.1399/13981402/−1398/1398−/13901401/1398−/13931400/1398−/1392
COO stretch./CCH bend.1348/13431337/−1350/1344−/13411349/1344−/13421349/1344−/1341
CH2 wag./CCH bend.1308/12921295/−1314/12931306/−1310/12931302/−1311/12931306/−
CH2 bend./HCN bend./phosphate anions 1211/1199−1214/11991175/11371214/11991160/−1214/11991181/−
CαN stretch./phosphate anions1074/10671059/−1064/10661056/−1060/10661058/−1072/10661062/−
NCH stretch.−/1005−−/1006−−/1002−−/1004−
HCN bend.936/940−934/941−934/940−937/940−
NH3+ rock./
NCα stretch.		875/867889/−875/868−873/867−/876877/869−/878
CH2 wag./CαN stretch.811/822796/784811/822−817/826−818/822−
S-H bend.774/772−777/773−775/772−775/772−
CβS stretch.681/692660/−684/692−682/692−685/692−
CβS stretch.−/639−/635−/639−/676–/639646/679–/639−/672
COO wag.614/−−620/−−/607620/620/615620/−−/−
CH2–CH–N bend.−/535−−/535−–/535−–/535−
S-S stretch./CCN bend.−−/496−−/496−−/496−/498−/496
CCC bend./CH2–CH–SH bend−/441−/469−/441−–/441−−/441−
Abbreviations: ῡ—wavenumber; bend.—bending; sym. stretch.—symmetric stretching; stretch.—stretching; rock.—rocking, wag.—wagging.
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Święch, D.; Piergies, N.; Palumbo, G.; Paluszkiewicz, C. In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution. Coatings 2023, 13, 175. https://doi.org/10.3390/coatings13010175

AMA Style

Święch D, Piergies N, Palumbo G, Paluszkiewicz C. In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution. Coatings. 2023; 13(1):175. https://doi.org/10.3390/coatings13010175

Chicago/Turabian Style

Święch, Dominika, Natalia Piergies, Gaetano Palumbo, and Czesława Paluszkiewicz. 2023. "In Situ and Ex Situ Raman Studies of Cysteine’s Behavior on a Titanium Surface in Buffer Solution" Coatings 13, no. 1: 175. https://doi.org/10.3390/coatings13010175

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