New Biomolecules and Drug Delivery Systems as Alternatives to Conventional Antibiotics

A special issue of Antibiotics (ISSN 2079-6382). This special issue belongs to the section "Novel Antimicrobial Agents".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 53823

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Guest Editor
Centre for Textile Science and Technology, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal
Interests: antimicrobial agents concomitant; synergistic and additive effects surface functionalization; antimicrobial properties; biomedical therapies; bioactive molecules; green synthesis; environmentally friendly; circular economy; waste materials’ second life
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Special Issue Information

Dear Colleagues,

New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are in great demand. For many years, antibiotics have been widely employed to treat infections. However, their excessive consumption and misuse have accelerated the rise of antibiotic-resistant microorganisms, which constitute one of the dominant challenges to global health. The antibiotic crisis is now a general concern and alternative biomolecules or drug delivery systems to treat infections are, therefore, urgently needed. From natural extracts to traditional medicine remedies, to newly engineered nanocapsules and nanoparticles to bio-based, biodegradable delivery platforms, many systems to fight infections have been proposed.

This Special Issue seeks manuscript submissions that further our understanding of the antimicrobial action of specialized biomolecules, recently engineered or chemically modified from their ancient origins, as alternatives to conventional antibiotics. Submissions on the response of microorganisms to these agents, their contribution to infection control, and prevention of serious conditions/illnesses from occurring or evolving, are especially encouraged. Publications that aim at a deeper understanding of the synergistic effects between different biomolecules and/or biomaterials (as delivery platforms) in infected wound care and establish their advantageous performance as a new step towards the resolution of the antibiotic crisis are also very welcome.

Dr. Helena P. Felgueiras
Guest Editor

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Keywords

  • Antimicrobial agents
  • Infection control
  • Baceria resistance
  • Natural extracts
  • Biomaterials functionalization
  • Biological delivery systems
  • Local and systemic drug administration
  • Antibiotics world crisis

Published Papers (14 papers)

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Editorial

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2 pages, 178 KiB  
Editorial
New Biomolecules and Drug Delivery Systems as Alternatives to Conventional Antibiotics
by Helena P. Felgueiras
Antibiotics 2022, 11(3), 318; https://doi.org/10.3390/antibiotics11030318 - 28 Feb 2022
Viewed by 1697
Abstract
New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are in high demand [...] Full article

Research

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15 pages, 3726 KiB  
Article
Experimental and Molecular Docking Studies of Cyclic Diphenyl Phosphonates as DNA Gyrase Inhibitors for Fluoroquinolone-Resistant Pathogens
by Neveen M. Saleh, Yasmine S. Moemen, Sara H. Mohamed, Ghady Fathy, Abdullah A. S. Ahmed, Ahmed A. Al-Ghamdi, Sami Ullah and Ibrahim El-Tantawy El Sayed
Antibiotics 2022, 11(1), 53; https://doi.org/10.3390/antibiotics11010053 - 1 Jan 2022
Cited by 8 | Viewed by 2490
Abstract
DNA gyrase and topoisomerase IV are proven to be validated targets in the design of novel antibacterial drugs. In this study, we report the antibacterial evaluation and molecular docking studies of previously synthesized two series of cyclic diphenylphosphonates (1ae and [...] Read more.
DNA gyrase and topoisomerase IV are proven to be validated targets in the design of novel antibacterial drugs. In this study, we report the antibacterial evaluation and molecular docking studies of previously synthesized two series of cyclic diphenylphosphonates (1ae and 2ae) as DNA gyrase inhibitors. The synthesized compounds were screened for their activity (antibacterial and DNA gyrase inhibition) against ciprofloxacin-resistant E.coli and Klebsiella pneumoniae clinical isolates having mutations (deletion and substitution) in QRDR region of DNA gyrase. The target compound (2a) that exhibited the most potent activity against ciprofloxacin Gram-negative clinical isolates was selected to screen its inhibitory activity against DNA gyrase displayed IC50 of 12.03 µM. In addition, a docking study was performed with inhibitor (2a), to illustrate its binding mode in the active site of DNA gyrase and the results were compatible with the observed inhibitory potency. Furthermore, the docking study revealed that the binding of inhibitor (2a) to DNA gyrase is mediated and modulated by divalent Mg2+ at good binding energy (–9.08 Kcal/mol). Moreover, structure-activity relationships (SARs) demonstrated that the combination of hydrazinyl moiety in conjunction with the cyclic diphenylphosphonate based scaffold resulted in an optimized molecule that inhibited the bacterial DNA gyrase by its detectable effect in vitro on gyrase-catalyzed DNA supercoiling activity. Full article
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11 pages, 1076 KiB  
Article
Co-Application of Allicin and Chitosan Increases Resistance of Rosa roxburghii against Powdery Mildew and Enhances Its Yield and Quality
by Jiaohong Li, Rongyu Li, Cheng Zhang, Zhenxiang Guo, Xiaomao Wu and Huaming An
Antibiotics 2021, 10(12), 1449; https://doi.org/10.3390/antibiotics10121449 - 25 Nov 2021
Cited by 16 | Viewed by 1687
Abstract
Powdery mildew, caused by Sphaerotheca sp., annually causes severe losses in yield and quality in Rosa roxburghii production areas of southwest China. In this study, the role of the co-application of allicin and chitosan in the resistance of R. roxburghii against powdery mildew [...] Read more.
Powdery mildew, caused by Sphaerotheca sp., annually causes severe losses in yield and quality in Rosa roxburghii production areas of southwest China. In this study, the role of the co-application of allicin and chitosan in the resistance of R. roxburghii against powdery mildew and its effects on growth, yield and quality of R. roxburghii were investigated. The laboratory toxicity test results show that allicin exhibited a superior antifungal activity against Sphaerotheca sp. with EC50 value of 148.65 mg kg−1. In the field, the foliar application of allicin could effectively enhance chitosan against powdery mildew with control efficacy of 85.97% by spraying 5% allicin microemulsion (ME) 100–time liquid + chitosan 100–time liquid, which was significantly (p < 0.01) higher than 76.70% of allicin, 70.93% of chitosan and 60.23% of polyoxin. The co-application of allicin and chitosan effectively enhanced the photosynthetic rate and chlorophyll of R. roxburghii compared with allicin, chitosan or polyoxin alone. Moreover, allicin used together with chitosan was more effective than allicin or chitosan alone in enhancing R. roxburghii plant growth and fruit yield as well as improving R. roxburghii fruit quality. This work highlights that the co-application of allicin and chitosan can be used as a green, cost-effective and environmentally friendly alternative strategy to conventional antibiotics for controlling powdery mildew of R. roxburghii. Full article
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14 pages, 1015 KiB  
Article
Prevalence, Patterns, Association with Biofilm Formation, Effects on Milk Quality and Risk Factors for Antibiotic Resistance of Staphylococci from Bulk-Tank Milk of Goat Herds
by Daphne T. Lianou, Efthymia Petinaki, Peter J. Cripps, Dimitris A. Gougoulis, Charalambia K. Michael, Katerina Tsilipounidaki, Anargyros Skoulakis, Angeliki I. Katsafadou, Natalia G. C. Vasileiou, Themis Giannoulis, Eleni I. Katsarou, Chrysoula Voidarou, Vasia S. Mavrogianni, Mariangela Caroprese and George C. Fthenakis
Antibiotics 2021, 10(10), 1225; https://doi.org/10.3390/antibiotics10101225 - 8 Oct 2021
Cited by 8 | Viewed by 2081
Abstract
The objectives of this work were to study the prevalence and the patterns of antibiotic resistance of staphylococcal isolates from bulk-tank milk of goat herds across Greece, to assess possible associations of the presence of antibiotic resistance with the quality of milk in [...] Read more.
The objectives of this work were to study the prevalence and the patterns of antibiotic resistance of staphylococcal isolates from bulk-tank milk of goat herds across Greece, to assess possible associations of the presence of antibiotic resistance with the quality of milk in these herds and to evaluate herd-related factors potentially associated with the presence of antibiotic resistance among these staphylococcal isolates. A cross-sectional study was performed on 119 goat herds in Greece. Bulk-tank milk samples were collected for bacteriological examination; staphylococcal isolates were evaluated for resistance to 20 antibiotics. Oxacillin-resistant, resistant to at least one antibiotic, and multi-resistant staphylococcal isolates were recovered from 5.0%, 30.3%, and 16.0% of herds, respectively. Of 80 isolates, 7.5% were resistant to oxacillin, 50.0% were resistant to at least one antibiotic and 27.5% were multi-resistant. Resistance was seen more frequently among coagulase-negative staphylococci (59.3%) than among Staphylococcus aureus (23.8%). Resistance was more frequent against penicillin and ampicillin (41.3% of isolates) and fosfomycin (27.5%). No association was found with biofilm formation by staphylococci. For recovery of oxacillin-resistant isolates, the presence of working staff in the herds emerged as a significant factor; respective factors for the isolation of staphylococci resistant to at least one antibiotic were part-time farming and high (>10) number of systemic disinfections in the farm annually. The same three factors concurrently were also identified to be significant for the recovery of multi-resistant isolates. Full article
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15 pages, 11631 KiB  
Article
Concomitant Effect of Quercetin- and Magnesium-Doped Calcium Silicate on the Osteogenic and Antibacterial Activity of Scaffolds for Bone Regeneration
by Arul Murugan Preethi and Jayesh R. Bellare
Antibiotics 2021, 10(10), 1170; https://doi.org/10.3390/antibiotics10101170 - 27 Sep 2021
Cited by 9 | Viewed by 3602
Abstract
Quercetin is a bioflavonoid which has a broad spectrum of biological activity. Due to its lower chemical stability, it is usually encapsulated, or a metal–quercetin complex is formed to enhance its biological activity at a lower concentration. Here, our novel approach was to [...] Read more.
Quercetin is a bioflavonoid which has a broad spectrum of biological activity. Due to its lower chemical stability, it is usually encapsulated, or a metal–quercetin complex is formed to enhance its biological activity at a lower concentration. Here, our novel approach was to form a quercetin complex to magnesium-doped calcium silicate (CMS) ceramics through a coprecipitation technique so as to take advantage of quercetin’s antibacterial activity within the antibacterial and osteogenic potential of the silicate. Due to quercetin’s inherent metal-chelating ability, (Ca+Mg)/Si increased with quercetin concentration. Quercetin in magnesium-doped calcium silicate ceramic showed concentration-dependent pro-oxidant and antioxidant activity in SaOS-2 with respect to quercetin concentration. By optimizing the relative concentration, we were able to achieve 3-fold higher proliferation and 1.6-fold higher total collagen at day 14, and a 1.7-fold higher alkaline phosphatase production at day 7 with respect to polycaprolactone/polyvinylpyrrolidone (PCL/PVP) scaffold. Quercetin is effective against Gram-positive bacteria such as S. aureus. Quercetin is coupled with CMS provided similar effect with lower quercetin concentration than quercetin alone. Quercetin reduced bacterial adhesion, proliferation and biofilm formation. Therefore, quercetin-coupled magnesium-doped calcium silicate not only enhanced osteogenic potential, but also reduced bacterial adhesion and proliferation. Full article
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11 pages, 3982 KiB  
Article
Live Biosensors for Ultrahigh-Throughput Screening of Antimicrobial Activity against Gram-Negative Bacteria
by Margarita N. Baranova, Polina A. Babikova, Arsen M. Kudzhaev, Yuliana A. Mokrushina, Olga A. Belozerova, Maxim A. Yunin, Sergey Kovalchuk, Alexander G. Gabibov, Ivan V. Smirnov and Stanislav S. Terekhov
Antibiotics 2021, 10(10), 1161; https://doi.org/10.3390/antibiotics10101161 - 24 Sep 2021
Cited by 7 | Viewed by 3423
Abstract
Gram-negative pathogens represent an urgent threat due to their intrinsic and acquired antibiotic resistance. Many recent drug candidates display prominent antimicrobial activity against Gram-positive bacteria being inefficient against Gram-negative pathogens. Ultrahigh-throughput, microfluidics-based screening techniques represent a new paradigm for deep profiling of antibacterial [...] Read more.
Gram-negative pathogens represent an urgent threat due to their intrinsic and acquired antibiotic resistance. Many recent drug candidates display prominent antimicrobial activity against Gram-positive bacteria being inefficient against Gram-negative pathogens. Ultrahigh-throughput, microfluidics-based screening techniques represent a new paradigm for deep profiling of antibacterial activity and antibiotic discovery. A key stage of this technology is based on single-cell cocultivation of microbiome biodiversity together with reporter fluorescent pathogen in emulsion, followed by the selection of reporter-free droplets using fluorescence-activated cell sorting. Here, a panel of reporter strains of Gram-negative bacteria Escherichia coli was developed to provide live biosensors for precise monitoring of antimicrobial activity. We optimized cell morphology, fluorescent protein, and selected the most efficient promoters for stable, homogeneous, high-level production of green fluorescent protein (GFP) in E. coli. Two alternative strategies based on highly efficient constitutive promoter pJ23119 or T7 promoter leakage enabled sensitive fluorescent detection of bacterial growth and killing. The developed live biosensors were applied for isolating potent E. coli-killing Paenibacillus polymyxa P4 strain by the ultrahigh-throughput screening of soil microbiome. The multi-omics approach revealed antibiotic colistin (polymyxin E) and its biosynthetic gene cluster, mediating antibiotic activity. Live biosensors may be efficiently implemented for antibiotic/probiotic discovery, environmental monitoring, and synthetic biology. Full article
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11 pages, 3640 KiB  
Article
Aerosolized Hypertonic Saline Hinders Biofilm Formation to Enhance Antibiotic Susceptibility of Multidrug-Resistant Acinetobacter baumannii
by Hui-Ling Lin, Chen-En Chiang, Mei-Chun Lin, Mei-Lan Kau, Yun-Tzu Lin and Chi-Shuo Chen
Antibiotics 2021, 10(9), 1115; https://doi.org/10.3390/antibiotics10091115 - 15 Sep 2021
Cited by 2 | Viewed by 2507
Abstract
Limited therapeutic options are available for multidrug-resistant Acinetobacter baumannii (MDR-AB), and the development of effective treatments is urgently needed. The efficacy of four aerosolized antibiotics (gentamicin, amikacin, imipenem, and meropenem) on three different MDR-AB strains was evaluated using hypertonic saline (HS, 7 g/100 [...] Read more.
Limited therapeutic options are available for multidrug-resistant Acinetobacter baumannii (MDR-AB), and the development of effective treatments is urgently needed. The efficacy of four aerosolized antibiotics (gentamicin, amikacin, imipenem, and meropenem) on three different MDR-AB strains was evaluated using hypertonic saline (HS, 7 g/100 mL) as the aerosol carrier. HS aerosol effectively hindered biofilm formation by specific MDR-AB strains. It could also interrupt the swarming dynamics of MDR-AB and the production of extracellular polymeric substances, which are essential for biofilm progression. Biofilms protect the microorganisms from antibiotics. The use of HS aerosol as a carrier resulted in a decreased tolerance to gentamicin and amikacin in the biofilm-rich MDR-AB. Moreover, we tested the aerosol characteristics of antibiotics mixed with HS and saline, and results showed that HS enhanced the inhaled delivery dose with a smaller particle size distribution of the four antibiotics. Our findings demonstrate the potential of using “old” antibiotics with our “new” aerosol carrier, and potentiate an alternative therapeutic strategy to eliminate MDR-AB infections from a biofilm-disruption perspective. Full article
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17 pages, 4218 KiB  
Article
Flavonoid-Coated Gold Nanoparticles as Efficient Antibiotics against Gram-Negative Bacteria—Evidence from In Silico-Supported In Vitro Studies
by Hani A. Alhadrami, Raha Orfali, Ahmed A. Hamed, Mohammed M Ghoneim, Hossam M. Hassan, Ahmed S. I. Hassane, Mostafa E. Rateb, Ahmed M. Sayed and Noha M. Gamaleldin
Antibiotics 2021, 10(8), 968; https://doi.org/10.3390/antibiotics10080968 - 12 Aug 2021
Cited by 22 | Viewed by 3507
Abstract
Flavonoids are a class of bioactive plant-derived natural products that exhibit a broad range of biological activities, including antibacterial ones. Their inhibitory activity toward Gram-positive bacterial was found to be superior to that against Gram-negative ones. In the present study, a number of [...] Read more.
Flavonoids are a class of bioactive plant-derived natural products that exhibit a broad range of biological activities, including antibacterial ones. Their inhibitory activity toward Gram-positive bacterial was found to be superior to that against Gram-negative ones. In the present study, a number of flavonoid-coated gold nanoparticles (GNPs) were designed to enhance the antibacterial effects of chrysin, kaempferol, and quercetin against a number of Gram-negative bacteria. The prepared GNPs were able to conjugate to these three flavonoids with conjugation efficiency ranging from 41% to 80%. Additionally, they were able to exert an enhanced antibacterial activity in comparison with the free flavonoids and the unconjugated GNPs. Quercetin-coated GNPs were the most active nano-conjugates and were able to penetrate the cell wall of E. coli. A number of in silico experiments were carried out to explain the conjugation efficiency and the antibacterial mechanisms of these flavonoids as follows: (i) these flavonoids can efficiently bind to the glutathione linker on the surface of GNPs via H-bonding; (ii) these flavonoids, particularly quercetin, were able to increase the bacterial membrane rigidity, and hence decrease its functionality; (iii) these flavonoids can inhibit E. coli’s DNA gyrase (Gyr-B) with IC50 values ranging from 0.9 to 3.9 µM. In conclusion, these bioactive flavonoid-based GNPs are considered to be very promising antibiotic candidates for further development and evaluation. Full article
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11 pages, 869 KiB  
Article
Bioactivity and Control Efficacy of the Novel Antibiotic Tetramycin against Various Kiwifruit Diseases
by Qiuping Wang, Cheng Zhang, Youhua Long, Xiaomao Wu, Yue Su, Yang Lei and Qiang Ai
Antibiotics 2021, 10(3), 289; https://doi.org/10.3390/antibiotics10030289 - 10 Mar 2021
Cited by 34 | Viewed by 2808
Abstract
Tetramycin, a novel polyene agriculture antibiotic, has excellent antimicrobial activity against many plant pathogens. In this study, the antimicrobial activities of tetramycin and conventional antibiotics on eight common pathogens and their field control efficacies against four serious diseases in kiwifruit were investigated. The [...] Read more.
Tetramycin, a novel polyene agriculture antibiotic, has excellent antimicrobial activity against many plant pathogens. In this study, the antimicrobial activities of tetramycin and conventional antibiotics on eight common pathogens and their field control efficacies against four serious diseases in kiwifruit were investigated. The results show that 0.3% tetramycin aqueous solutions (AS) exhibited the superior antibacterial and antifungal activity against Pseudomonas syringae pv. actinidiae, Pseudomonas fulva, Agrobacterium tumefaciens, Botryosphaeriadothidea, Phomopsis sp., Alternaria tenuissima, Armillariella mellea and Phytophthora cactorum of kiwifruit pathogens with EC50 values of 1.21, 1.24, 0.72, 0.14, 0.09, 0.16, 0.06 and 0.17 mg kg−1, respectively. These EC50 values of tetramycin were much higher than those of conventional kasugamycin, zhongshengmycin or polyoxin. Meanwhile, 0.3% tetramycin AS possessed the good field control efficacies for canker, soft rot, blossom blight and brown spot disease of kiwifruit with 74.45, 83.55, 84.74 and 89.62%. Moreover, 0.3% tetramycin AS application notably increased fruit resistance substances contents, activated fruit superoxide dismutase and polyphenoloxidase activities, as well as remarkably enhanced fruit growth, improved fruit quality and storability. This study highlights that tetramycin can be used as a preferred alternative to conventional antibiotics in kiwifruit production. Full article
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13 pages, 2570 KiB  
Article
Grapefruit Seed Extract as a Natural Derived Antibacterial Substance against Multidrug-Resistant Bacteria
by Hee-Won Han, Jin-Hwan Kwak, Tae-Su Jang, Jonathan Campbell Knowles, Hae-Won Kim, Hae-Hyoung Lee and Jung-Hwan Lee
Antibiotics 2021, 10(1), 85; https://doi.org/10.3390/antibiotics10010085 - 18 Jan 2021
Cited by 18 | Viewed by 9655
Abstract
Multidrug-resistant (MDR) bacteria are increasing due to the abuse and misuse of antibiotics, and nosocomial infections by MDR bacteria are also increasing. The aim of this study was to identify new substances that can target MDR bacteria among 12 plant extracts that are [...] Read more.
Multidrug-resistant (MDR) bacteria are increasing due to the abuse and misuse of antibiotics, and nosocomial infections by MDR bacteria are also increasing. The aim of this study was to identify new substances that can target MDR bacteria among 12 plant extracts that are known to have antibacterial effects. The experiments were performed by the disk diffusion test and microdilution minimum inhibitory concentration (MIC) test, as described by the Clinical and Laboratory Standards Institute (CLSI). By screening against methicillin-sensitive Staphylococcus aureus (MSSA), grapefruit seed extract (GSE) was selected from 12 plant extracts for subsequent experiments. GSE showed antibacterial effects against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) in the disk diffusion test. Even at the lowest concentration, GSE showed antibacterial activity in the microdilution MIC test. As a result, we can conclude that GSE is a naturally derived antibacterial substance that exhibits a favorable antibacterial effect even at a very low concentration, so it is a good candidate for a natural substance that can be used to prevent or reduce nosocomial infections as coating for materials used in medical contexts or by mixing a small amount with other materials. Full article
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22 pages, 5311 KiB  
Article
Green Synthesis of Silver Nanoparticles and Evaluation of Their Antibacterial Activity against Multidrug-Resistant Bacteria and Wound Healing Efficacy Using a Murine Model
by Vajravathi Lakkim, Madhava C. Reddy, Roja Rani Pallavali, Kakarla Raghava Reddy, Ch Venkata Reddy, Inamuddin, Anwar L. Bilgrami and Dakshayani Lomada
Antibiotics 2020, 9(12), 902; https://doi.org/10.3390/antibiotics9120902 - 13 Dec 2020
Cited by 48 | Viewed by 6514
Abstract
Green nanotechnology has significant applications in various biomedical science fields. In this study, green-synthesized silver nanoparticles, prepared by using Catharanthus roseus and Azadirachta indica extracts, were characterized using UV–Vis spectroscopy, dynamic light scattering, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Silver [...] Read more.
Green nanotechnology has significant applications in various biomedical science fields. In this study, green-synthesized silver nanoparticles, prepared by using Catharanthus roseus and Azadirachta indica extracts, were characterized using UV–Vis spectroscopy, dynamic light scattering, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Silver nanoparticles (Ag NPs) synthesized from leaf extracts of C. roseus and A. indica effectively inhibited the growth of multidrug-resistant (MDR) bacteria isolated from patients with septic wound infections. The maximum bacteriolytic activity of the green-synthesized Ag NPs of C. roseus and A. indica against the MDR bacterium K. Pneumoniae was shown by a zone of inhibition of 19 and 16 mm, respectively. C. roseus Ag NPs exhibited more bacteriolytic activity than A. indica Ag NPs in terms of the zone of inhibition. Moreover, these particles were effective in healing wounds in BALB/c mice. Ag NPs of C. roseus and A. indica enhanced wound healing by 94% ± 1% and 87% ± 1%, respectively. Our data suggest that Ag NPs from C. roseus and A. indicia ameliorate excision wounds, and wound healing could be due to their effective antimicrobial activity against MDR bacteria. Hence, these Ag NPs could be potential therapeutic agents for the treatment of wounds. Full article
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16 pages, 3747 KiB  
Article
Poly-ε-caprolactone Nanoparticles Loaded with 4-Nerolidylcatechol (4-NC) for Growth Inhibition of Microsporum canis
by Vanessa Raquel Greatti, Fernando Oda, Rodrigo Sorrechia, Bárbara Regina Kapp, Carolina Manzato Seraphim, Ana Carolina Villas Bôas Weckwerth, Marlus Chorilli, Patrícia Bento Da Silva, Josimar O. Eloy, Marcelo J. Kogan, Javier O. Morales and Rosemeire Cristina Linhari Rodrigues Pietro
Antibiotics 2020, 9(12), 894; https://doi.org/10.3390/antibiotics9120894 - 11 Dec 2020
Cited by 8 | Viewed by 2297
Abstract
Dermatophyte fungal infections are difficult to treat because they need long-term treatments. 4-Nerolidylcatechol (4-NC) is a compound found in Piper umbellatum that has been reported to demonstrate significant antifungal activity, but is easily oxidizable. Due to this characteristic, the incorporation in nanostructured systems [...] Read more.
Dermatophyte fungal infections are difficult to treat because they need long-term treatments. 4-Nerolidylcatechol (4-NC) is a compound found in Piper umbellatum that has been reported to demonstrate significant antifungal activity, but is easily oxidizable. Due to this characteristic, the incorporation in nanostructured systems represents a strategy to guarantee the compound’s stability compared to the isolated form and the possibility of improving antifungal activity. The objective of this study was to incorporate 4-NC into polymeric nanoparticles to evaluate, in vitro and in vivo, the growth inhibition of Microsporum canis. 4-NC was isolated from fresh leaves of P. umbellatum, and polymer nanoparticles of polycaprolactone were developed by nanoprecipitation using a 1:5 weight ratio (drug:polymer). Nanoparticles exhibited excellent encapsulation efficiency, and the antifungal activity was observed in nanoparticles with 4-NC incorporated. Polymeric nanoparticles can be a strategy employed for decreased cytotoxicity, increasing the stability and solubility of substances, as well as improving the efficacy of 4-NC. Full article
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Review

Jump to: Editorial, Research

23 pages, 1263 KiB  
Review
Antibiotics- and Heavy Metals-Based Titanium Alloy Surface Modifications for Local Prosthetic Joint Infections
by Jaime Esteban, María Vallet-Regí and John J. Aguilera-Correa
Antibiotics 2021, 10(10), 1270; https://doi.org/10.3390/antibiotics10101270 - 19 Oct 2021
Cited by 12 | Viewed by 3003
Abstract
Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due [...] Read more.
Prosthetic joint infection (PJI) is the second most common cause of arthroplasty failure. Though infrequent, it is one of the most devastating complications since it is associated with great personal cost for the patient and a high economic burden for health systems. Due to the high number of patients that will eventually receive a prosthesis, PJI incidence is increasing exponentially. As these infections are provoked by microorganisms, mainly bacteria, and as such can develop a biofilm, which is in turn resistant to both antibiotics and the immune system, prevention is the ideal approach. However, conventional preventative strategies seem to have reached their limit. Novel prevention strategies fall within two broad categories: (1) antibiotic- and (2) heavy metal-based surface modifications of titanium alloy prostheses. This review examines research on the most relevant titanium alloy surface modifications that use antibiotics to locally prevent primary PJI. Full article
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34 pages, 6192 KiB  
Review
Recent Advances in Fiber–Hydrogel Composites for Wound Healing and Drug Delivery Systems
by Marta O. Teixeira, Joana C. Antunes and Helena P. Felgueiras
Antibiotics 2021, 10(3), 248; https://doi.org/10.3390/antibiotics10030248 - 2 Mar 2021
Cited by 35 | Viewed by 6508
Abstract
In the last decades, much research has been done to fasten wound healing and target-direct drug delivery. Hydrogel-based scaffolds have been a recurrent solution in both cases, with some reaching already the market, even though their mechanical stability remains a challenge. To overcome [...] Read more.
In the last decades, much research has been done to fasten wound healing and target-direct drug delivery. Hydrogel-based scaffolds have been a recurrent solution in both cases, with some reaching already the market, even though their mechanical stability remains a challenge. To overcome this limitation, reinforcement of hydrogels with fibers has been explored. The structural resemblance of fiber–hydrogel composites to natural tissues has been a driving force for the optimization and exploration of these systems in biomedicine. Indeed, the combination of hydrogel-forming techniques and fiber spinning approaches has been crucial in the development of scaffolding systems with improved mechanical strength and medicinal properties. In this review, a comprehensive overview of the recently developed fiber–hydrogel composite strategies for wound healing and drug delivery is provided. The methodologies employed in fiber and hydrogel formation are also highlighted, together with the most compatible polymer combinations, as well as drug incorporation approaches creating stimuli-sensitive and triggered drug release towards an enhanced host response. Full article
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