UV Light-Induced Generation of Reactive Oxygen Species and Antimicrobial Properties of Cellulose Fabric Modified by 3,3',4,4'-Benzophenone Tetracarboxylic Acid

Surface photosterilization of implantable silicone biomaterials: structural and functional characterization

Hospital-acquired infections (HAIs) remain one of the major challenges faced by the global healthcare system. The increasing rate of pathogenic resistance against antibiotics suggests that alternative treatments are needed to control recurrent infections. Catheter-associated urinary tract infections (CAUTIs) are the third most common type of HAI worldwide, and this is mainly due to indwelling devices being excellent substrates for bacterial adhesion and growth. Subsequent biofilm formation on the implant surface acts as a constant nidus of bacteria and infection, thereby contributing to increased rates of patient morbidity and mortality. Here, we propose a simple and cost-effective method to sterilize silicone-based implant surfaces and prevent initial bacterial colonization, using Polydimethylsiloxane (PDMS) and an embedded ruthenium photosensitizer (PS). Exposure to LED light triggers potent photokilling action, resulting in significant bactericidal activity as evidenced by the number of adherent bacteria being below the level of detection (<10 CFU/mL) after 24 h. Live/dead staining studies using fluorescence microscopy indicated significant reduction in surface-adhered bacterial growth and biofilm formation. This potent antibacterial activity was verified in vivo, with exposure of contaminated PDMS coupons containing PS to LED prior to implantation resulting in over 99.5% reduction in adherent bacteria compared to controls over the 3-day implantation period. Histological analysis of the implantation site of PDMS+PS samples, in the absence of bacteria, revealed no adverse reactions. This was also confirmed using in vitro cytotoxicity studies. Tensile strength, surface roughness, hydrophobicity, and the development of encrustation of surface-treated groups exhibit comparable or improved properties to bare PDMS.

Near-ultraviolet irradiation to stimulate unmodified polyether ether ketone to achieve stable and sustainable antibacterial activity

OBJECTIVES

This study aims to investigate the cytotoxicity and sustainable antibacterial activity of unmodified PEEK under specific wavelength light treatment (365 nm), and its antibacterial mechanism was also preliminarily discussed.

METHODS

A near-ultraviolet source with a wavelength of 365 nm and a power of 5 W were selected. The irradiation time was 30 min, and the distance was 100 mm. A water contact angle tester was used to characterize the surface of the PEEK after 1-15 light treatments. MC3TC-E1 cells were used to evaluate the cytotoxicity of the materials under light treatment. Five kinds of common oral bacteria were detected in vitro, and antibacterial efficiency was determined by colony-forming unit (CFU) and scanning electron microscope (SEM). The antibacterial mechanism of PEEK under light was preliminarily discussed by spectrophotometry. The membrane rupture of Staphylococcus aureus and Escherichia coli was detected by lactate dehydrogenase. Staphylococcus aureus and Staphylococcus mutans were selected for the cyclic antibacterial test. Statistical analysis was performed by one-way analysis of variance and Tukey multiple range test. A significance level of 0.05 was considered (α = 0.05).

RESULTS

The results of the cell experiment showed that PEEK had no cytotoxicity (P > 0.05). CFU results showed that PEEK had an obvious antibacterial effect on Staphylococcus aureus, Staphylococcus mutans, Staphylococcus gordonii and Staphylococcus sanguis, but had no antibacterial effect on Escherichia coli (P < 0.05). The SEM results also verified the above antibacterial effect. The existence of singlet oxygen was confirmed by spectrophotometry. Meanwhile, the rupture of Staphylococcus aureus membrane was verified by lactate dehydrogenase assay. The water contact angle of the PEEK surface did not change significantly after 15 cycles of light treatment. Cyclic antibacterial experiments showed that the antibacterial effect was sustainable.

CONCLUSIONS

This study showed that PEEK has good cytocompatibility with stable and sustainable antibacterial properties under near-ultraviolet. It provides a new idea to solve the non-antibacterial property of PEEK, and also provides a theoretical basis for its further application in dentistry.

High-breathable, antimicrobial and water-repellent face mask for breath monitoring

Face masks with multiple functionalities and exceptional durability have attracted increasing interests during the COVID-19 pandemic. How to integrate the antibacterial property, comfortability during long-time wearing, and breath monitoring capability together on a face mask is still challenging. Here we developed a kind of face mask that assembles the particles-free water-repellent fabric, antibacterial fabric, and hidden breath monitoring device together, resulting in the highly breathable, water-repellent, and antibacterial face mask with breath monitoring capability. Based on the rational design of the functional layers, the mask shows exceptional repellency to micro-fogs generated during breathing while maintaining high air permeability and inhibiting the passage of bacteria-containing aerogel. More importantly, the multi-functional mask can also monitor the breath condition in a wireless and real-time fashion, and collect the breath information for epidemiological analysis. The resultant mask paves the way to develop multi-functional breath-monitoring masks that can aid the prevention of the secondary transmission of bacteria and viruses while preventing potential discomfort and face skin allergy during long-period wearing.

Cellulose-Based Nanomaterials Advance Biomedicine: A Review

There are various biomaterials, but none fulfills all requirements. Cellulose biopolymers have advanced biomedicine to satisfy high market demand and circumvent many ecological concerns. This review aims to present an overview of cellulose knowledge and technical biomedical applications such as antibacterial agents, antifouling, wound healing, drug delivery, tissue engineering, and bone regeneration. It includes an extensive bibliography of recent research findings from fundamental and applied investigations. Cellulose-based materials are tailorable to obtain suitable chemical, mechanical, and physical properties required for biomedical applications. The chemical structure of cellulose allows modifications and simple conjugation with several materials, including nanoparticles, without tedious efforts. They render the applications cheap, biocompatible, biodegradable, and easy to shape and process.

Nanoprotection from SARS-COV-2: would nanotechnology help in Personal Protection Equipment (PPE) to control the transmission of COVID-19?

The coronavirus disease 2019 (COVID-19) has caused a worldwide outbreak. The severe acute respiratory syndrome coronavirus 2 virus can be transmitted human-to-human through droplets and close contact where personal protective equipment (PPE) is imperative to protect the individuals. The advancement of nanotechnology with significant nanosized properties can confer a higher form of protection. Incorporation of nanotechnology into facemasks can exhibit antiviral properties. Nanocoating on surfaces can achieve self-disinfecting purposes and be applied in highly populated places. Moreover, nano-based hand sanitizers can confer better sterilizing efficacies with low skin irritation as compared to alcohol-based hand sanitizers. The present review discusses the incorporation of nanotechnology into nano-based materials and coatings in facemasks, self-surface disinfectants and hand sanitizers, in the hope to contribute to the current understanding of PPE to combat COVID-19.

Contributions of photochemistry to bio-based antibacterial polymer materials

Surgical site infections constitute a major health concern that may be addressed by conferring antibacterial properties to surgical tools and medical devices via functional coatings. Bio-sourced polymers are particularly well-suited to prepare such coatings as they are usually safe and can exhibit intrinsic antibacterial properties or serve as hosts for bactericidal agents. The goal of this Review is to highlight the unique contribution of photochemistry as a green and mild methodology for the development of such bio-based antibacterial materials. Photo-generation and photo-activation of bactericidal materials are illustrated. Recent efforts and current challenges to optimize the sustainability of the process, improve the safety of the materials and extend these strategies to 3D biomaterials are also emphasized.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

A Biosynthesized Near-Infrared-Responsive Nanocomposite Biomaterial for Antimicrobial and Antibiofilm Treatment

Photodynamic inactivation (PDI) has become an appealing alternative strategy to treat infections without developing resistance to microbes. In PDI treatment, near-infrared (NIR) light is preferred because it causes less damage to normal tissues and leads to better penetration in deep tissues. Here, we develop an NIR-responsive nanomedicine for efficient broad-spectrum antimicrobial photodynamic treatment. By harnessing the biosynthetic capability of a bacterial cellulose-producing microorganism, we construct a nanocomposite biomaterial to deliver and recycle the nanomedicine. Our simple one-step biosynthetic approach does not impede the antimicrobial potency of the nanomedicine under NIR activation and requires no chemical modification. The resulting nanocomposite has been tested in antimicrobial treatment of different microorganisms, exhibiting a great potential to eliminate pathogens in biofilms and to treat in vivo infections.

Functionalized Masks: Powerful Materials against COVID-19 and Future Pandemics

The outbreak of COVID-19 revealed the vulnerability of commercially available face masks. Without having antibacterial/antiviral activities, the current masks act only as filtering materials of the aerosols containing microorganisms. Meanwhile, in surgical masks, the viral and bacterial filtration highly depends on the electrostatic charges of masks. These electrostatic charges disappear after 8 h, which leads to a significant decline in filtration efficiency. Therefore, to enhance the masks' protection performance, fabrication of innovative masks with more advanced functions is in urgent demand. This review summarizes the various functionalizing agents which can endow four important functions in the masks including i) boosting the antimicrobial and self-disinfectant characteristics via incorporating metal nanoparticles or photosensitizers, ii) increasing the self-cleaning by inserting superhydrophobic materials such as graphenes and alkyl silanes, iii) creating photo/electrothermal properties by forming graphene and metal thin films within the masks, and iv) incorporating triboelectric nanogenerators among the friction layers of masks to stabilize the electrostatic charges and facilitating the recharging of masks. The strategies for creating these properties toward the functionalized masks are discussed in detail. The effectiveness and limitation of each method in generating the desired properties are well-explained along with addressing the prospects for the future development of masks.

Electrospun antibacterial poly(vinyl alcohol)/Ag nanoparticles membrane grafted with 3,3',4,4'-benzophenone tetracarboxylic acid for efficient air filtration

In this study, poly(vinyl alcohol) (PVA) membranes containing Ag nanoparticles (AgNPs) were prepared by electrospinning and grafted copolymerization with 3,3',4,4'-benzophenone tetracarboxylic acid (BPTA) to provide better mechanical properties, lower water vapor transmittance, and higher antibacterial activity (against Staphylococcus aureus and Escherichia coli) than the PVA/AgNPs membrane. The PVA/AgNPs/BPTA membrane showed higher antibacterial activity than the other membranes, and it produced inhibition zones with diameters of 18.12 ± 0.08 and 16.41 ± 0.05 mm against S. aureus and E. coli, respectively. The PVA/AgNPs/BPTA membrane was found to be capable of promoting reactive oxygen species (ROS) formation under both light and dark conditions. Cycling experiments performed following ROS quenching showed that the best-performing composite membrane retained >70% of its original OH⋅ radical and H₂O₂ charging capacity after seven cycles. In the filtration test, the electrospun nanofibrous membranes showed high filtration efficiencies of 99.98% for sodium chloride (NaCl). In addition, these membranes maintained a relatively low pressure drop of 168 Pa with a basis weight of 2.1 g m^-2. Thus, the PVA/AgNPs/BPTA membrane was concluded to be a promising medical protective material offering the benefits of structural stability and reusability.

Light-Induced Production of Reactive Oxygen Species by a Novel Water-Soluble Benzophenone Derivative Containing Quaternary Ammonium Groups and Its Assembly on the Protein Fiber Surface

Developing an efficient antimicrobial surface has important significance in the field of advanced biomaterials. A novel water-soluble benzophenone tetracarboxylamine derivative containing two quaternary ammonium groups, 3,3'-[4,4'-carbonyl-diphthalimide-]-bis(N-benzyl-N,N-dimethyl-N-propyl-1-aminium)dichloride (BPTCA-N), as a photoactive antibacterial agent was designed and synthesized. The ability of BPTCA-N to generate reactive oxygen species (ROS) in solution was investigated by light-induced activity. Its antibacterial activity in a dark environment or UV exposure was tested on Staphylococcus aureus and Escherichia coli. The influences of different solvents and the pH values on the ability of BPTCA-N to generate ROS were also discussed. BPTCA-N possessed high photoactivity and efficient ROS generation ability. The generation of hydroxyl radicals could be greatly affected by addition of other solvents and H⁺ or OH^-. For the BPTCA-N solution at a concentration of 0.2 mmol/L, the reduction of S. aureus and E. coli could all reach 99.99%. The BPTCA-N compound was assembled onto wool protein fibers. The modified protein fabrics also showed excellent photoactivity and antibacterial property against S. aureus and E. coli. For the wool fabric modified with 30 g/L of BPTCA-N, the reduction of S. aureus could reach 99.91% and that of E. coli was 91.23%. BPTCA-N had the synergistic antibacterial effect of quaternary ammonium salt and benzophenones. It has potential application in the biomedical field as highly effective antimicrobial agent or antimicrobial biomaterial.

Phenelzine reduces the oxidative damage induced by peroxynitrite in plasma lipids and proteins

Peroxynitrite is a reactive nitrogen species produced in the intravascular compartment from superoxide anion and nitric oxide. Peroxynitrite destroys blood plasma proteins and membranes of red blood cells and of platelets. This explains why excessive production of peroxynitrite contributes to diseases and to ageing. Therapeutics that antagonize peroxynitrite may delay ageing and the progression of disease. We developed an in vitro assay that allows the investigation of the oxidative damage caused by peroxynitrite in the intravascular compartment. This assay correlates the damage with the rate of formation of protein carbonyl groups, 3-nitrotyrosine (3-NT) and thiobarbituric acid reactive substances. Using this assay, we evaluated the ability of phenelzine, a scavenger of reactive aldehydes, to antagonize the effects of peroxynitrite. Herein, we showed that phenelzine significantly decreased the lipid peroxidative damage caused by peroxynitirite in blood plasma and platelets. Moreover, it inhibited carbonyl group and 3-NT formation in blood plasma and platelet proteins.

Generation of hydroxyl radicals and effective whitening of cotton fabrics by H2O2 under UVB irradiation

Chemically crosslinked cotton fabrics may show yellowish appearance, especially citric acid (CA) crosslinked ones. Hydrogen peroxide (H₂O₂) bleaching under alkaline condition could improve the whiteness of the CA-crosslinked cotton fabrics but sacrificing certain crosslinking performance of the products due to alkaline hydrolysis of ester connections. Regular H₂O₂ and UV irradiation (H₂O₂/UV) system can destroy color but also damage fibers due to the use of very short wavelength of UVC such as 254nm or shorter. Now, it was found that longer wavelength UV such as 312nm performed better in H₂O₂/UV systems on CA-crosslinked cotton fabrics. The reaction mechanism and potential product of the oxidation reaction on CA-crosslinked cotton were proposed and demonstrated. UV-vis spectrophotometer and Fourier transform infrared spectroscopy provided key evidence. Whiteness, wrinkle recovery angle and tensile strength of the fabrics were evaluated, and the results support the mechanism. The process is environmentally friendly and highly efficient.

Supramolecular Double-Helix Formation by Diastereoisomeric Conformations of Configurationally Enantiomeric Macrocycles

Solid-state superstructures, resulting from assemblies programmed by homochirality, are attracting considerable attention. In addition, artificial double-helical architectures are being investigated, especially in relation to the ways in which homochiral small molecules can be induced to yield helical forms as a result of chiral induction. Herein, we report the highly specific self-assembly upon crystallization of a double-helical superstructure from an enantiopure macrocyclic dimer which adopts two diastereoisomeric conformations in a molar ratio of 1.5:1 in dimethyl sulfoxide. These two conformational diastereoisomers self-organize-and self-sort-in the crystalline phase in equimolar proportions to form two single-handed helices which are complementary to each other, giving rise to the assembly of a double helix that is stabilized by intermolecular [C-H···O] and π-π stacking interactions. The observed self-sorting phenomenon occurs on going from a mixed-solvent system containing two equilibrating conformational diastereoisomers, presumably present in unequal molar proportions, into the solid state. The diastereoisomeric conformations are captured upon crystallization in a 1:1 molar ratio in the double-helical superstructure, whose handedness is dictated by the choice of the enantiomeric macrocyclic dimer. The interconversion of the two conformational diastereoisomers derived from each configurationally enantiomeric macrocycle was investigated in CD₃SOCD₃ solution by variable-temperature ¹H NMR spectroscopy (VT NMR) and circular dichroism (VT CD). The merging of the resonances for the protons corresponding to the two diastereoisomers at a range of coalescence temperatures in the VT NMR spectra and occurrence of the isosbestic points in the VT CD spectra indicate that the two diastereoisomers are interconverting slowly in solution on the ¹H NMR time scale but rapidly on the laboratory time scale. To the best of our knowledge, the self-assembly of such solid-state superstructures from two conformational diastereoisomers of a homochiral macrocycle is a rare, if not unique, occurrence.

Surface-Selective Preferential Production of Reactive Oxygen Species on Piezoelectric Ceramics for Bacterial Killing

Reactive oxygen species (ROS) can be used to kill bacterial cells, and thus the selective generation of ROS from material surfaces is an emerging direction in antibacterial material discovery. We found the polarization of piezoelectric ceramic causes the two sides of the disk to become positively and negatively charged, which translate into cathode and anode surfaces in an aqueous solution. Because of the microelectrolysis of water, ROS are preferentially formed on the cathode surface. Consequently, the bacteria are selectively killed on the cathode surface. However, the cell experiment suggested that the level of ROS is safe for normal mammalian cells.