2024

Jump to: 2022, 2021

18 pages, 5944 KiB

Open AccessArticle

Antiviral and Antibacterial 3D-Printed Products Functionalised with Poly(hexamethylene biguanide)

by Anson M. Y. Luk, Chris K. Y. Lo, Jiachi Amber Chiou, Chi-Hang Ngai, Ki Law, Tsz-Long Lau, Wan-Xue Chen, Matthew Hui and Chi-Wai Kan

Polymers 2024, 16(3), 312; https://doi.org/10.3390/polym16030312 - 23 Jan 2024

Viewed by 735

Abstract

Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray coatings at public facilities are the typical measures taken to protect people from coronaviruses and other [...] Read more.

Infection prevention and public health are a vital concern worldwide, especially during pandemics such as COVID-19 and seasonal influenza. Frequent manual disinfection and use of chemical spray coatings at public facilities are the typical measures taken to protect people from coronaviruses and other pathogens. However, limitations of human resources and coating durability, as well as the safety of disinfectants used are the major concerns in society during a pandemic. Non-leachable antimicrobial agent poly(hexamethylene biguanide) (PHMB) was mixed into photocurable liquid resins to produce novel and tailor-made covers for public facilities via digital light processing, which is a popular 3D printing technique for satisfactory printing resolution. Potent efficacies of the 3D-printed plastics were achieved in standard antibacterial assessments against S. aureus, E. coli and K. pneumoniae. A total of 99.9% of Human coronavirus 229E was killed after being in contact with the 3D-printed samples (containing the promising PHMB formulation) for two hours. In an eight-week field test in Hong Kong Wetland Park, antibacterial performances of the specially designed 3D-printed covers analysed by environmental swabbing were also found to be satisfactory. With these remarkable outcomes, antimicrobial products prepared by digital light processing 3D printing can be regarded as a reliable solution to long-term infection prevention and control. Full article

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2022

Jump to: 2024, 2021

29 pages, 8107 KiB

Open AccessReview

Face Masks to Combat Coronavirus (COVID-19)—Processing, Roles, Requirements, Efficacy, Risk and Sustainability

by Md Zillur Rahman, Md Enamul Hoque, Md Rubel Alam, Md Abdur Rouf, Saiful Islam Khan, Huaizhong Xu and Seeram Ramakrishna

Polymers 2022, 14(7), 1296; https://doi.org/10.3390/polym14071296 - 23 Mar 2022

Cited by 31 | Viewed by 12741

Abstract

Increasingly prevalent respiratory infectious diseases (e.g., COVID-19) have posed severe threats to public health. Viruses including coronavirus, influenza, and so on can cause respiratory infections. A pandemic may potentially emerge owing to the worldwide spread of the virus through persistent human-to-human transmission. However, [...] Read more.

Increasingly prevalent respiratory infectious diseases (e.g., COVID-19) have posed severe threats to public health. Viruses including coronavirus, influenza, and so on can cause respiratory infections. A pandemic may potentially emerge owing to the worldwide spread of the virus through persistent human-to-human transmission. However, transmission pathways may vary; respiratory droplets or airborne virus-carrying particles can have a key role in transmitting infections to humans. In conjunction with social distancing, hand cleanliness, and other preventative measures, the use of face masks is considered to be another scientific approach to combat ubiquitous coronavirus. Different types of face masks are produced using a range of materials (e.g., polypropylene, polyacrylonitrile, polycarbonate, polyurethane, polystyrene, polyester and polyethylene) and manufacturing techniques (woven, knitted, and non-woven) that provide different levels of protection to the users. However, the efficacy and proper disposal/management of the used face masks, particularly the ones made of non-biodegradable polymers, pose great environmental concerns. This review compiles the recent advancements of face masks, covering their requirements, materials and techniques used, efficacy, challenges, risks, and sustainability towards further enhancement of the quality and performance of face masks. Full article

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2021

Jump to: 2024, 2022

19 pages, 5401 KiB

Open AccessArticle

Low-Temperature Thermal Degradation of Disinfected COVID-19 Non-Woven Polypropylene—Based Isolation Gown Wastes into Carbonaceous Char

by M. M. Harussani, Umer Rashid, S. M. Sapuan and Khalina Abdan

Polymers 2021, 13(22), 3980; https://doi.org/10.3390/polym13223980 - 17 Nov 2021

Cited by 15 | Viewed by 2491

Abstract

Yields of carbonaceous char with a high surface area were enhanced by decreasing the temperature to improve the conversion of hazardous plastic polypropylene (PP), the major component in abundantly used isolation gowns. This study applied pyrolysis with different low pyrolytic temperatures to convert [...] Read more.

Yields of carbonaceous char with a high surface area were enhanced by decreasing the temperature to improve the conversion of hazardous plastic polypropylene (PP), the major component in abundantly used isolation gowns. This study applied pyrolysis with different low pyrolytic temperatures to convert disinfected PP-based isolation gown waste (PP-IG) into an optimised amount of char yields. A batch reactor with a horizontal furnace was used to mediate the thermal decomposition of PP-IG. Enhanced surface area and porosity value of PP-IG derived char were obtained via an optimised slow pyrolysis approach. The results showed that the amount of yielded char was inversely proportional to the temperature. This process relied heavily on the process parameters, especially pyrolytic temperature. Additionally, as the heating rate decreased, as well as longer isothermal residence time, the char yields were increased. Optimised temperature for maximum char yields was recorded. The enhanced SBET values for the char and its pore volume were collected, ~24 m² g⁻¹ and ~0.08 cm³ g⁻¹, respectively. The char obtained at higher temperatures display higher volatilisation and carbonisation. These findings are beneficial for the utilisation of this pyrolysis model in plastic waste management and conversion of PP-IG waste into char for further activated carbon and fuel briquettes applications, with the enhanced char yields, amidst the COVID-19 pandemic. Full article

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19 pages, 16005 KiB

Open AccessArticle

Unveiling the Effect of Low pH on the SARS-CoV-2 Main Protease by Molecular Dynamics Simulations

by Haruna Luz Barazorda-Ccahuana, Miroslava Nedyalkova, Francesc Mas and Sergio Madurga

Polymers 2021, 13(21), 3823; https://doi.org/10.3390/polym13213823 - 05 Nov 2021

Cited by 7 | Viewed by 2118

Abstract

(1) Background: Main Protease (Mpro) is an attractive therapeutic target that acts in the replication and transcription of the SARS-CoV-2 coronavirus. Mpro is rich in residues exposed to protonation/deprotonation changes which could affect its enzymatic function. This work aimed to explore the effect [...] Read more.

(1) Background: Main Protease (Mpro) is an attractive therapeutic target that acts in the replication and transcription of the SARS-CoV-2 coronavirus. Mpro is rich in residues exposed to protonation/deprotonation changes which could affect its enzymatic function. This work aimed to explore the effect of the protonation/deprotonation states of Mpro at different pHs using computational techniques. (2) Methods: The different distribution charges were obtained in all the evaluated pHs by the Semi-Grand Canonical Monte Carlo (SGCMC) method. A set of Molecular Dynamics (MD) simulations was performed to consider the different protonation/deprotonation during 250 ns, verifying the structural stability of Mpro at different pHs. (3) Results: The present findings demonstrate that active site residues and residues that allow Mpro dimerisation was not affected by pH changes. However, Mpro substrate-binding residues were altered at low pHs, allowing the increased pocket volume. Additionally, the results of the solvent distribution around S

γ

, H

γ

, N

δ

1 and H

δ

1 atoms of the catalytic residues Cys145 and His41 showed a low and high-water affinity at acidic pH, respectively. It which could be crucial in the catalytic mechanism of SARS-CoV-2 Mpro at low pHs. Moreover, we analysed the docking interactions of PF-00835231 from Pfizer in the preclinical phase, which shows excellent affinity with the Mpro at different pHs. (4) Conclusion: Overall, these findings indicate that SARS-CoV-2 Mpro is highly stable at acidic pH conditions, and this inhibitor could have a desirable function at this condition. Full article

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7 pages, 1188 KiB

Open AccessCommunication

Study on the Development of Antiviral Spandex Fabric Coated with Poly(Hexamethylene Biguanide) Hydrochloride (PHMB)

by Wen-Yi Wang, Sui-Lung Yim, Chun-Ho Wong and Chi-Wai Kan

Polymers 2021, 13(13), 2122; https://doi.org/10.3390/polym13132122 - 28 Jun 2021

Cited by 13 | Viewed by 2908

Abstract

The spread of COVID-19 has brought about huge losses around the world. This study aims to investigate the applicability of PHMB used for developing antiviral spandex clothing against coronavirus. PHMB was qualitatively determined on the surface of spandex fabrics by using BPB. The [...] Read more.

The spread of COVID-19 has brought about huge losses around the world. This study aims to investigate the applicability of PHMB used for developing antiviral spandex clothing against coronavirus. PHMB was qualitatively determined on the surface of spandex fabrics by using BPB. The antiviral analysis shows that the PHMB-treated spandex fabric can kill 99% of the coronavirus within 2 h of contact, which suggests that the spandex fabric treated with PHMB could be used for developing antiviral clothing against coronaviruses for containing the transmission of COVID-19 in high-risk places. Furthermore, PHMB-treated spandex fabrics were shown excellent antibacterial activity against gram-positive S. aureus and gram-negative K. pneumoniae. The hand feel properties of Spandex fabric were not significantly affected by the PHMB coating in addition to the wrinkle recovery, which was obviously improved after PHMB coating. Full article

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10 pages, 11405 KiB

Open AccessArticle

Copper-Coated Polypropylene Filter Face Mask with SARS-CoV-2 Antiviral Ability

by Sunghoon Jung, Jun-Yeoung Yang, Eun-Yeon Byeon, Do-Geun Kim, Da-Gyum Lee, Sungweon Ryoo, Sanggu Lee, Cheol-Woong Shin, Ho Won Jang, Hyo Jung Kim and Seunghun Lee

Polymers 2021, 13(9), 1367; https://doi.org/10.3390/polym13091367 - 22 Apr 2021

Cited by 65 | Viewed by 10074

Abstract

Face masks will be used to prevent pandemic recurrence and outbreaks of mutant SARS-CoV-2 strains until mass immunity is confirmed. The polypropylene (PP) filter is a representative disposable mask material that traps virus-containing bioaerosols, preventing secondary transmission. In this study, a copper thin [...] Read more.

Face masks will be used to prevent pandemic recurrence and outbreaks of mutant SARS-CoV-2 strains until mass immunity is confirmed. The polypropylene (PP) filter is a representative disposable mask material that traps virus-containing bioaerosols, preventing secondary transmission. In this study, a copper thin film (20 nm) was deposited via vacuum coating on a spunbond PP filter surrounding a KF94 face mask to provide additional protection and lower the risk of secondary transmission. Film adhesion was improved using oxygen ion beam pretreatment, resulting in cuprous oxide formation on the PP fiber without structural deformation. The copper-coated mask exhibited filtration efficiencies of 95.1 ± 1.32% and 91.6 ± 0.83% for NaCl and paraffin oil particles, respectively. SARS-CoV-2 inactivation was evaluated by transferring virus-containing media onto the copper-coated PP filters and subsequently adding Vero cells. Infection was verified using real-time polymerase chain reaction and immunochemical staining. Vero cells added after contact with the copper-coated mask did not express the RNA-dependent RNA polymerase and envelope genes of SARS-CoV-2. The SARS-CoV-2 nucleocapsid immunofluorescence results indicated a reduction in the amount of virus of more than 75%. Therefore, copper-coated antiviral PP filters could be key materials in personal protective equipment, as well as in air-conditioning systems. Full article

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20 pages, 389 KiB

Open AccessReview

Electrospun Nanofibrous Scaffolds: Review of Current Progress in the Properties and Manufacturing Process, and Possible Applications for COVID-19

by Mohamed Kchaou, Mohammed Alquraish, Khaled Abuhasel, Ahmad Abdullah and Ashraf A. Ali

Polymers 2021, 13(6), 916; https://doi.org/10.3390/polym13060916 - 16 Mar 2021

Cited by 14 | Viewed by 3400

Abstract

Over the last twenty years, researchers have focused on the potential applications of electrospinning, especially its scalability and versatility. Specifically, electrospun nanofiber scaffolds are considered an emergent technology and a promising approach that can be applied to biosensing, drug delivery, soft and hard [...] Read more.

Over the last twenty years, researchers have focused on the potential applications of electrospinning, especially its scalability and versatility. Specifically, electrospun nanofiber scaffolds are considered an emergent technology and a promising approach that can be applied to biosensing, drug delivery, soft and hard tissue repair and regeneration, and wound healing. Several parameters control the functional scaffolds, such as fiber geometrical characteristics and alignment, architecture, etc. As it is based on nanotechnology, the concept of this approach has shown a strong evolution in terms of the forms of the materials used (aerogels, microspheres, etc.), the incorporated microorganisms used to treat diseases (cells, proteins, nuclei acids, etc.), and the manufacturing process in relation to the control of adhesion, proliferation, and differentiation of the mimetic nanofibers. However, several difficulties are still considered as huge challenges for scientists to overcome in relation to scaffolds design and properties (hydrophilicity, biodegradability, and biocompatibility) but also in relation to transferring biological nanofibers products into practical industrial use by way of a highly efficient bio-solution. In this article, the authors review current progress in the materials and processes used by the electrospinning technique to develop novel fibrous scaffolds with suitable design and that more closely mimic structure. A specific interest will be given to the use of this approach as an emergent technology for the treatment of bacteria and viruses such as COVID-19. Full article

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23 pages, 389 KiB

Open AccessReview

Ultraviolet-C as a Viable Reprocessing Method for Disposable Masks and Filtering Facepiece Respirators

by Talita Nicolau, Núbio Gomes Filho and Andrea Zille

Polymers 2021, 13(5), 801; https://doi.org/10.3390/polym13050801 - 05 Mar 2021

Cited by 15 | Viewed by 2478

Abstract

In normal conditions, discarding single-use personal protective equipment after use is the rule for its users due to the possibility of being infected, particularly for masks and filtering facepiece respirators. When the demand for these protective tools is not satisfied by the companies [...] Read more.

In normal conditions, discarding single-use personal protective equipment after use is the rule for its users due to the possibility of being infected, particularly for masks and filtering facepiece respirators. When the demand for these protective tools is not satisfied by the companies supplying them, a scenario of shortages occurs, and new strategies must arise. One possible approach regards the disinfection of these pieces of equipment, but there are multiple methods. Analyzing these methods, Ultraviolet-C (UV-C) becomes an exciting option, given its germicidal capability. This paper aims to describe the state-of-the-art for UV-C sterilization in masks and filtering facepiece respirators. To achieve this goal, we adopted a systematic literature review in multiple databases added to a snowball method to make our sample as robust as possible and encompass a more significant number of studies. We found that UV-C’s germicidal capability is just as good as other sterilization methods. Combining this characteristic with other advantages makes UV-C sterilization desirable compared to other methods, despite its possible disadvantages. Full article

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