Construction of Functional Coatings with Durable and Broad-Spectrum Antibacterial Potential Based on Mussel-Inspired Dendritic Polyglycerol and in Situ-Formed Copper Nanoparticles

A post-synthetic modification strategy for enhancing Pt adsorption efficiency in MOF/polymer composites

Growing polymers inside porous metal-organic frameworks (MOFs) can allow incoming guests to access the backbone of otherwise non-porous polymers, boosting the number and/or strength of available adsorption sites inside the porous support. In the present work, we have devised a novel post-synthetic modification (PSM) strategy that allows one to graft metal-chelating functionality onto a polymer backbone while inside MOF pores, enhancing the material's ability to recover Pt(iv) from complex liquids. For this, polydopamine (PDA) was first grown inside of a MOF, known as Fe-BTC (or MIL-100 Fe). Next, a small thiol-containing molecule, 2,3-dimercapto-1-propanol (DIP), was grafted to the PDA via a Michael addition. After the modification of the PDA, the Pt adsorption capacity and selectivity were greatly enhanced, particularly in the low concentration regime, due to the high affinity of the thiols towards Pt. Moreover, the modified composite was found to be highly selective for precious metals (Pt, Pd, and Au) over common base metals found in electronic waste (i.e., Pb, Cu, Ni, and Zn). X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption spectroscopy (XAS) provided insight into the Pt adsorption/reduction process. Last, the PSM was extended to various thiols to demonstrate the versatility of the chemistry. It is hoped that this work will open pathways for the future design of novel adsorbents that are fine-tuned for the rapid, selective retrieval of high-value and/or critical metals from complex liquids.

Methods to improve antibacterial properties of PEEK: A review

As a thermoplastic and bioinert polymer, polyether ether ketone (PEEK) serves as spine implants, femoral stems, cranial implants, and joint arthroplasty implants due to its mechanical properties resembling the cortical bone, chemical stability, and radiolucency. Although there are standards and antibiotic treatments for infection control during and after surgery, the infection risk is lowered but can not be eliminated. The antibacterial properties of PEEK implants should be improved to provide better infection control. This review includes the strategies for enhancing the antibacterial properties of PEEK in four categories: immobilization of functional materials and functional groups, forming nanocomposites, changing surface topography, and coating with antibacterial material. The measuring methods of antibacterial properties of the current studies of PEEK are explained in detail under quantitative, qualitative, andin vivomethods. The mechanisms of bacterial inhibition by reactive oxygen species generation, contact killing, trap killing, and limited bacterial adhesion on hydrophobic surfaces are explained with corresponding antibacterial compounds or techniques. The prospective analysis of the current studies is done, and dual systems combining osteogenic and antibacterial agents immobilized on the surface of PEEK are found the promising solution for a better implant design.

Biocompatible copper formate-based nanoparticles with strong antibacterial properties for wound healing

Copper-based antibacterial materials have emerged as a potential alternative for combating bacterial infections, which continue to pose significant health risks. Nevertheless, the use of copper-based nanoparticles as antibacterial agents has faced challenges due to their toxicity towards cells and tissues. To overcome this obstacle, we propose a new approach using a contact-active copper-based nanoparticles called polydopamine (PDA)-coated copper-amine (Cuf-TMB@PDA). The positively charged surface of Cuf-TMB@PDA enables efficient targeting of negatively charged bacteria, allowing controlled release of Cu(II) into the bacterial cell membrane. Moreover, Cuf-TMB@PDA exhibits similar ·OH signals as Cuf-TMB suspensions in previous work. In cytotoxicity assays conducted over 72 h, Cuf-TMB@PDA demonstrated an efficacy of 98.56%, while releasing lower levels of Cu(II) that were less harmful to cells, resulting in enhanced antimicrobial effects. These antimicrobial properties are attributed to the synergistic effects of charge-contact activity of PDA, controlled release of Cu(II), and free radicals. Subsequent in vivo experiments confirmed the strong antimicrobial potency of Cuf-TMB@PDA and its ability to promote wound healing.

Copper-based nanoparticles against microbial infections

Drug-resistant bacteria and highly infectious viruses are among the major global threats affecting the human health. There is an immediate need for novel strategies to tackle this challenge. Copper-based nanoparticles (CBNPs) have exhibited a broad antimicrobial capacity and are receiving increasing attention in this context. In this review, we describe the functionalization of CBNPs, elucidate their antibacterial and antiviral activity as well as applications, and briefly review their toxicity, biodistribution, and persistence. The limitations of the current study and potential solutions are also shortly discussed. The review will guide the rational design of functional nanomaterials for antimicrobial application. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

Fabrication of polydopamine reduced CuO nanoparticle-alginate composite nanogels for management of Pseudomonas synringae pv. tabaci in tobacco

BACKGROUND

The wildfire disease on tobacco can seriously hinder plants. Meanwhile, its pathogen, Pseudomonas syringae, can also infect over 200 plants and threat agriculture production. However, the disease usually occurs after summer rains which washes away most copper (Cu)-based bactericides, allowing the disease to invade. Therefore, we fabricate a new nanogel with high disease control and anti-erosion ability and study the effects of the reductant on the performance of the copper oxide nanoparticle (CuONP) composite nanogel.

RESULTS

Polydopamine (PDA) is a polycation for both in situ reduction of CuONP in alginate nanogels and for adjusting the copper ion (Cu²⁺ ) releasing rate in this work. The composite nanogel fabricated by PDA (PDA-CuONP@ALGNP@CTAC) had a higher Cu²⁺ releasing rate, damaging the pathogen membrane more efficiently, allowing for better disease control and plant growth promotion when compared to sodium borohydride (SBH)-fabricated nanogel (SBH-CuONP@ALGNP@CTAC) or the commercial bactericide, thiodiazole copper. The PDA-CuONP@ALGNP@CTAC had a high anti-erosion ability and could remain adhered to the leaf surface even after five rain event simulations.

CONCLUSION

The addition of polycations (like PDA) into CuONP composite nanogel could increase the Cu²⁺ releasing rate, resulting in improved disease management when compared to SBH-CuONP@ALGNP@CTAC or thiodiazole copper. The PDA containing gel had an improved anti-erosion ability and water resistance. This new composite nanogel has a high potential for wildfire disease control, improving agricultural production. © 2022 Society of Chemical Industry.

Fabrication of CuO nanoparticles composite ε-polylysine-alginate nanogel for high-efficiency management of Alternaria alternate

Although ε-poly-l-lysine (ε-PL) has a good potential as a green fungicide, high concentration is usually required during its controlling of plant disease. On the other hand, same problems also appeared in the study of CuONP based nano pesticides. In this manuscript, a new composite alginate nanogel (ALGNP) that containing CuONP and ε-PL was fabricated via in situ reduction of CuONP in nanogel and ε-PL surface coating. Based on the chelation of amide bond of ε-PL and Cu²⁺ released by CuONP, the synergy effect between Cu²⁺ and ε-PL layer of the nanogel make the nanogel (CuONP@ALGNP@PL) performed high anti-fungal activity under low Cu²⁺ and ε-PL concentration (Cu concentration was 40.09 μg/mL, ε-PL concentration was 11.90 μg/mL). Study showed that the nanogel could more significantly destroy the fungal cell membrane than CuONP@ALGNP and ALGNP@PL, also better than commercial fungicide CuCaSO₄ (Cu concentration was 120 μg/mL). Furthermore, CuONP@ALGNP@PL could seriously affect the spore production, spore germination rate and bud tube elongation length of Alternaria alternate. Moreover, CuONP@ALGNP@PL also inhibit Botrytis cinerea, Phytophthora, Thanatephorus cucumeris and Fusarium graminearum. These results showed that composite of CuONP and ε-PL based on nanogel can decrease the raw materials application amount, and achieve a high disease controlling ability, which provides a new perspective for preventing fungal diseases.

Nanomaterial-Based Antimicrobial Coating for Biomedical Implants: New Age Solution for Biofilm-Associated Infections

Recently, the upsurge in hospital-acquired diseases has put global health at risk. Biomedical implants being the primary source of contamination, the development of biomedical implants with antimicrobial coatings has attracted the attention of a large group of researchers from around the globe. Bacteria develops biofilms on the surface of implants, making it challenging to eradicate them with the standard approach of administering antibiotics. A further issue of current concern is the fast resurgence of resistance to conventional antibiotics. As nanotechnology continues to advance, various types of nanomaterials have been created, including 2D nanoparticles and metal and metal oxide nanoparticles with antimicrobial properties. Researchers from all over the world are using these materials as a coating agent for biomedical implants to create an antimicrobial environment. This comprehensive and contemporary review summarizes various metals, metal oxide nanoparticles, 2D nanomaterials, and their composites that have been used or may be used in the future as an antimicrobial coating agent for biomedical implants, as well as their succinct mode of action to combat biofilm-associated infection and diseases.

Antibacterial Inorganic Coating of Calcium Silicate Hydrate Substrates by Copper Incorporation

Under environmental conditions, biofilms can oftentimes be found on different surfaces, accompanied by the structural degradation of the substrate. Since high-copper-content paints were banned in the EU, a solution for the protection of these surfaces has to be found. In addition to hydrophobation, making the surfaces inherently biofilm-repellent is a valid strategy. We want to accomplish this via the metal exchange in calcium silicate hydrate (CSH) substrates with transition metals. As has been shown with Europium, even small amounts of metal can have a great influence on the material properties. To effectively model CSH surfaces, ultrathin CSH films were grown on silicon wafers using Ca(OH)2 solutions. Subsequently, copper was incorporated as an active component via ion exchange. Biofilm development is quantified using a multiple-resistant Pseudomonas aeruginosa strain described as a strong biofilm former cultivated in the culture medium for 24 h. Comprehensive structural and chemical analyses of the substrates are done by environmental scanning electron microscopy (ESEM), transmission Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Results do not show any structural deformation of the substrates by the incorporation of the Cu combined with three-dimensional (3D) homogeneous distribution. While the copper-free CSH phase shows a completely random distribution of the bacteria in biofilms, the samples with copper incorporation reveal lower bacterial colonization of the modified surfaces with an enhanced cluster formation.

Metal-Based Nanoparticles: Antibacterial Mechanisms and Biomedical Application

The growing increase in antibiotic-resistant bacteria has led to the search for new antibacterial agents capable of overcoming the resistance problem. In recent years, nanoparticles (NPs) have been increasingly used to target bacteria as an alternative to antibiotics. The most promising nanomaterials for biomedical applications are metal and metal oxide NPs, due to their intrinsic antibacterial activity. Although NPs show interesting antibacterial properties, the mechanisms underlying their action are still poorly understood, limiting their use in clinical applications. In this review, an overview of the mechanisms underlying the antibacterial activity of metal and metal oxide NPs will be provided, relating their efficacy to: (i) bacterial strain; (ii) higher microbial organizations (biofilm); (iii) and physico-chemical properties of NPs. In addition, bacterial resistance strategies will be also discussed to better evaluate the feasibility of the different treatments adopted in the clinical safety fields. Finally, a wide analysis on recent biomedical applications of metal and metal oxide NPs with antibacterial activity will be provided.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Breathable, Antibacterial, and Biocompatible Collagen Fiber Network Decorated with Zwitterionic Silver Nanoparticles for Plantar Pressure Monitoring

Foot plantar pressure monitoring and gait analysis are of great significant in footwear design, sport biomechanics, injury prevention, and early warning of disease. Flexible and wearable smart insoles pave a feasible way for these application scenarios. However, the majority of the currently developed smart insoles are composed of synthetic polymers (e.g., plastics, rubbers, etc.), leading to inevitable problems associated with air permeability, hygiene condition, biocompatibility, and wearing comfort. Here, a new paradigm of a natural collagen fiber network (CFN) with soft and breathable features, which can be obtained by facilely treating animal hides via conventional leather pretreatment process, is selected as substrate material for constructing smart insoles due to its high permeability and porosity. Further, biocompatible zwitterionic silver nanoparticles (AgNPs) with both carboxybetaine and catechol groups on the interface were designed for firmly and uniformly immobilization onto the hierarchical micro-/nanoscale fibers of CFN through mussel-inspired catechol/amino chemistry, giving rise to both good antibacterial property and pressure sensing capability of the resultant material. The finally developed smart insole by using the AgNPs decorated CFN exhibits good capability for plantar pressure mapping and gait feature analysis. Especially, the smart insole will be very suitable for pressure monitoring and gait analysis of a diabetic foot with sensitive skin that requires a high biocompatible and antibacterial environment.

Fabrication of copper nanoparticle composite nanogel for high-efficiency management of Pseudomonas syringae pv. tabaci on tobacco

BACKGROUND

Copper nanoparticles (CuNPs) can release copper ions (Cu2+ ) to control bacterial diseases on crops. However, the high concentration of the CuNPs applied in disease controlling can highly limit their application. In this work, by in situ reducing CuNPs in alginate nanogels and coated with cetyl trimethyl ammonium chloride (CTAC), a CuNP composite nanogel was fabricated as a new nanopesticide with low copper content.

RESULTS

Data showed that the CTAC coating would affect the antibacterial activity and leaf surface adhesion of the nanogel, while CuNP content could also influence the membrane damage ability of the gel. The nanogel could depress the growth of bacteria by rupturing its membrane and show a minimum inhibitory concentration (MIC) as low as 500 μg mL-1 , which only contain 58 μg mL-1 CuNP, and achieve a 64% of therapeutic efficiency (with 1000 μg mL-1 nanogel) in in vivo experiments, higher than that of commercial bactericide thiodiazole copper. Furthermore, the application of the nanogel can also perform a growth-promoting effect on the plant, which may be due to the supplement of copper element provided by CuNP.

CONCLUSION

The CuNP composite nanogel fabricated in this work performed high leaf disease controllability and safety compared to the commercial bactericide thiodiazole copper. We hope this nanogel can provide a potential high-efficiency nano-bactericide that can be used in the leaf bacterial disease control.

Novel Adhesive Nanocarriers Based on Mussel-Inspired Polyglycerols for the Application onto Mucosal Tissues

A synthetic route for adhesive core-multishell (CMS) nanocarriers for application to the oral mucosa was established using mussel-inspired catechol moieties. The three CMS nanocarriers with 8%, 13%, and 20% catechol functionalization were evaluated for loading capacity using Nile red, showing an overall loading of 1 wt%. The ability of Nile red loaded and functionalized nanocarriers to bind to a moist mucosal surface was tested in two complementary adhesion assays under static and dynamic conditions using monolayers of differentiated gingival keratinocytes. Adhesion properties of functionalized nanocarriers were compared to the adhesion of the non-functionalized nanocarrier. In both assays, the CMS nanocarrier functionalized with 8% catechol exhibited the strongest adhesion compared to its catechol-free counterpart and the CMS nanocarriers functionalized with 13% and 20% catechol.

Alloyed nanostructures integrated metal-phenolic nanoplatform for synergistic wound disinfection and revascularization

New materials for combating bacteria-caused infection and promoting the formation of microvascular networks during wound healing are of vital importance. Although antibiotics can be used to prevent infection, treatments that can disinfect and accelerate wound healing are scarce. Herein, we engineer a coating that is both highly compatible with current wound dressing substrates and capable of simultaneously disinfecting and revascularizing wounds using a metal-phenolic nanoplatform containing an alloyed nanostructured architecture (Ag@Cu-MPN_NC). The alloyed nanostructure is formed by the spontaneous co-reduction and catalytic disproportionation reaction of multiple metal ions on a foundation metal-phenolic supramolecular layer. This synergistic presence of metals greatly improves the antibacterial activity against both Gram-negative and Gram-positive pathogenic bacteria, while demonstrating negligible cytotoxicity to normal tissue. In infected rat models, the Ag@Cu-MPN_NC could kill bacteria efficiently, promoting revascularization and accelerate wound closure with no adverse side effects in infected in vivo models. In other words, this material acts as a combination therapy by inhibiting bacterial invasion and modulating bio-nano interactions in the wound.

Combatting persisted and biofilm antimicrobial resistant bacterial by using nanoparticles

Some bacteria can withstand the existence of an antibiotic without undergoing any genetic changes. They are neither cysts nor spores and are one of the causes of disease recurrence, accounting for about 1% of the biofilm. There are numerous approaches to eradication and combating biofilm-forming organisms. Nanotechnology is one of them, and it has shown promising results against persister cells. In the review, we go over the persister cell and biofilm in extensive detail. This includes the biofilm formation cycle, antibiotic resistance, and treatment with various nanoparticles. Furthermore, the gene-level mechanism of persister cell formation and its therapeutic interventions with nanoparticles were discussed.

Silver Nanodot Decorated Dendritic Copper Foam As a Hydrophobic and Mechano-Chemo Bactericidal Surface

The present work investigates the time-dependent antibacterial activity of the silver nanodot decorated dendritic copper foam nanostructures against Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive) bacteria. An advanced antibacterial and antifouling surface is fabricated utilizing the collective antibacterial properties of silver nanodots, chitosan, and dendritic copper foam nanostructures. The porous network of the Ag nanodot decorated Cu foam is made up of nanodendrites, which reduce the wettability of the surface. Hence, the surface exhibits hydrophobic nature and inhibits the growth of bacterial flora along with the elimination of dead bacterial cells. The fabricated surface exhibits a water contact angle (WCA) of 158.7 ± 0.17°. Specifically, we tested the fabricated material against both the Gram-positive and Gram-negative bacterial models. The antibacterial activity of the fabricated surface is evident from the growth inhibition percentage of bacterial strains of Escherichia coli (72.30 ± 0.60%) and Bacillus subtilis (48.30 ± 1.71%). The micrographs obtained from scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) of the treated cells show the damaged cellular structures of the bacteria, which is strong evidence of successful antibacterial action. The antibacterial effect can be attributed to the synergistic mechano-chemo mode of action involving mechanical disruption of the bacterial cell wall by the nanoprotrusions present on the Cu dendrites along with the chemical interaction of the Ag nanodots with vital intracellular components.

Polydopamine antibacterial materials

Recently, the development of polydopamine (PDA) has demonstrated numerous excellent performances in free radical scavenging, UV shielding, photothermal conversion, and biocompatibility. These unique properties enable PDA to be widely used as efficient antibacterial materials for various applications. Accordingly, PDA antibacterial materials mainly include free-standing PDA materials and PDA-based composite materials. In this review, an overview of PDA antibacterial materials is provided to summarize these two types of antibacterial materials in detail, including the fabrication strategies and antibacterial mechanisms. The future development and challenges of PDA in this field are also presented. It is hoped that this review will provide an insight into the future development of antibacterial functional materials based on PDA.

Antibacterial and Antiviral Functional Materials: Chemistry and Biological Activity toward Tackling COVID-19-like Pandemics

The ongoing worldwide pandemic due to COVID-19 has created awareness toward ensuring best practices to avoid the spread of microorganisms. In this regard, the research on creating a surface which destroys or inhibits the adherence of microbial/viral entities has gained renewed interest. Although many research reports are available on the antibacterial materials or coatings, there is a relatively small amount of data available on the use of antiviral materials. However, with more research geared toward this area, new information is being added to the literature every day. The combination of antibacterial and antiviral chemical entities represents a potentially path-breaking intervention to mitigate the spread of disease-causing agents. In this review, we have surveyed antibacterial and antiviral materials of various classes such as small-molecule organics, synthetic and biodegradable polymers, silver, TiO2, and copper-derived chemicals. The surface protection mechanisms of the materials against the pathogen colonies are discussed in detail, which highlights the key differences that could determine the parameters that would govern the future development of advanced antibacterial and antiviral materials and surfaces.

A mussel-bioinspired multi-functional hyperbranched polymeric coating with integrated antibacterial and antifouling activities for implant interface modification

On the basis of a function integrating strategy, a mussel-inspired hyperbranched polymeric coating with antibacterial and antifouling properties was ingeniously designed and synthesized for the interface modification of implants.

Fabrication of Bacteria- and Blood-Repellent Superhydrophobic Polyurethane Sponge Materials

Biofilm and thrombus formation on surfaces results in significant morbidity and mortality worldwide, which highlights the importance of the development of efficacious fouling-prevention approaches. In this work, novel highly robust and superhydrophobic coatings with outstanding multiliquid repellency, bactericidal performance, and extremely low bacterial and blood adhesion are fabricated by a simple two-step dip-coating method. The coatings are prepared combining 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS-17)-coated hydrophobic zinc oxide and copper nanoparticles to construct hierarchical micro/nanostructures on commercial polyurethane (PU) sponges followed by polydimethylsiloxane (PDMS) treatment that is used to improve the binding degree between the nanoparticles and the sponge surface. The micro/nanotextured samples can repel various liquids including water, milk, coffee, juice, and blood. Relative to the original PU, the superhydrophobic characteristics of the fabricated sponge cause a significant reduction in the adhesion of bacteria (Staphylococcus aureus) by up to 99.9% over a 4-day period in a continuous drip-flow bioreactor. The sponge is also highly resistant to the adhesion of fibrinogen and activated platelets with ∼76 and 64% reduction, respectively, hence reducing the risk of blood coagulation and thrombus formation. More importantly, the sponge can sustain its superhydrophobicity even after being subjected to different types of harsh mechanical damage such as finger-wiping, knife-scratching, tape-peeling, hand-kneading, hand-rubbing, bending, compress-release (1000 cycles) tests, and 1000 cm sandpaper abrasion under 250 g of loading. Hence, this novel hybrid surface with robustness and the ability to resist blood adhesion and bacterial contamination makes it an attractive candidate for use in diverse application areas.

Recent Advances in Nanotechnology-Aided Materials in Combating Microbial Resistance and Functioning as Antibiotics Substitutes

The ongoing escalation of drug-resistant bacteria creates the leading challenges for human health. Current predictions show that deaths due to bacterial illness will be more in comparison to cancer in 2050. Irrational use of antibiotics, prolonged regimen and using as a prophylactic treatment for various infections are leading cause of microbial resistance. It is an emerging approach to introduce evolving nanomaterials (NMs) as a base of antibacterial therapy to overcome the bacterial resistance pattern. NMs can implement several bactericidal ways and turn into a challenge for bacteria to survive and develop resistance against NMs. All the pathways depend on the surface chemistry, shape, core material and size of NMs. Because of these reasons, NMs based stuff shows a critical role in advancing the treatment efficiency by interacting with the cellular system of bacteria and functioned as an antibiotic substitute. We divided this review into two sections. The first part highlights the development of microbial resistance to antibiotics and their mechanisms. The second section details the NMs mechanisms to combat antibiotic resistance. In short, we try to summarize the advances in NMs role to deal with microbial resistance and giving solution as antibiotics substitute.

Functionalization of Polymers and Nanomaterials for Biomedical Applications: Antimicrobial Platforms and Drug Carriers

The use of polymers and nanomaterials has vastly grown for industrial and biomedical sectors during last years. Before any designation or selection of polymers and their nanocomposites, it is vital to recognize the targeted applications which require these platforms to be modified. Surface functionalization to introduce the desired type and quantity of reactive functional groups to target a cell or tissue in human body is a pivotal approach to improve the physicochemical and biological properties of these materials. Herein, advances in the functionalized polymer and nanomaterials surfaces are highlighted along with their applications in biomedical fields, e.g., antimicrobial therapy and drug delivery.

Antimicrobial Copper-Based Materials and Coatings: Potential Multifaceted Biomedical Applications

Surface contamination by microbes leads to several detrimental consequences like hospital- and device-associated infections. One measure to inhibit surface contamination is to confer the surfaces with antimicrobial properties. Copper's antimicrobial properties have been known since ancient times, and the recent resurgence in exploiting copper for application as antimicrobial materials or coatings is motivated by the growing concern about antibiotic resistance and the pressure to reduce antibiotic use. Copper, unlike silver, demonstrates rapid and high microbicidal efficacy against pathogens that are in close contact under ambient indoor conditions, which enhances its range of applicability. This review highlights the mechanisms behind copper's potent antimicrobial property, the design and fabrication of different copper-based antimicrobial materials and coatings comprising metallic copper/copper alloys, copper nanoparticles or ions, and their potential for practical applications. Finally, as the antimicrobial coatings market is expected to grow, we offer our perspectives on the implications of increased copper release into the environment and the potential ecotoxicity effects and possibility of development of resistant genes in pathogens.

Surface modification approaches for prevention of implant associated infections

In this highlight, we summarize the surface modification approaches for development of infection-resistant coatings for biomedical devices and implants. We discuss the relevant key and highly cited research that have been published over the last five years which report the generation of infection-resistant coatings. An important strategy utilized to prevent bacterial adhesion and biofilm formation on device/implant surface is anti-adhesive protein repellant polymeric coatings based on polymer brushes or highly hydrated hydrogel networks. Further, the attachment of antimicrobial agents that can efficiently kill bacteria on the surface while also prevent bacterial adhesion on the surface is also investigated. Other approaches include the incorporation of antimicrobial agents to the surface coating resulting in a depot of bactericides which can be released on-demand or with time to prevent bacterial colonization on the surface that kill the adhered bacteria on the surface to make surface infection resistant.

Mussel-inspired coordination functional polymer brushes-decorated rGO-stabilized silver nanoparticles composite for antibacterial application

A catechol-terminated coordination functional polymer-modified rGO supported AgNPs composite was fabricated. Grafted polymer brushes improve the material's hydrophilicity and dispersion stability of AgNPs on rGO, enhancing antibacterial activity.

Cu(II)-Based Water-Dispersible Humic Acid: Synthesis, Characterizations, and Antifungal and Growth-Promoting Performances

The complex synthesis process, low utilization, and single function of fungicides have seriously hindered the development of fungicides in resistance to rice sheath blight. Here, an inexpensive and multifunctional Cu(II)-based water-dispersible humic acid (Cu-WH) fungicide with growth-promoting ability was developed with a simple method. A 3D molybdate carbon hierarchical nanosphere (MoO₂-C-HN) catalyst was successfully synthesized using a green route and applied in a solid-phase activation of lignite to obtain water-dispersible humic acid. Cu(II)-based water-dispersible humic acid (Cu-WH) was then formed through a simple reaction of Cu(II) and the humic acid. The resultant Cu-WH showed strong antifungal performance against Rhizoctonia solani in laboratory incubation experiments. After being treated with Cu3-WH (0.1 mg L^-1), the control efficiency of rice sheath blight at 1, 3, and 5 days after infection was 90.54%, 78.96%, and 66.31%, respectively. It also enhanced the water-holding capacity of the substrate and thus effectively improved the growth of rice seedlings. In comparison to commercial rice seedling substrate, the substrate treated with 8 wt % of Cu3-WH increased plant height, stem diameter, fresh weight, and chlorophyll content by 19.23%, 35.91%, 14.52%, and 42.85%, respectively. The newly developed Cu-WH thus can be used as a novel low-cost efficient fungicide and growth stimulator to treat rice sheath blight as well as to increase rice production.

Antibacterial Copper-Hydroxyapatite Composite Coatings via Electrochemical Synthesis

Antibacterial copper-hydroxyapatite (Cu-HA) composite coatings on titanium were synthesized using a novel process consisting of two consecutive electrochemical reactions. In the first stage, HA nanocrystals were grown on titanium using the cathodic electrolytic synthesis. The HA-coated titanium was then used as the cathode in a second reaction stage to electrochemically reduce Cu²⁺ ions in solution to metallic Cu nanoparticles. Reaction conditions were found that result in nanoscale Cu particles growing on the surface of the HA crystals. The two-stage synthesis allows facile control of copper content in the HA coatings. Antibacterial activity was measured by culturing Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) in the presence of coatings having varying copper contents. The coatings displayed copper concentration-dependent antibacterial activity against both types of bacteria, likely due to the slow release of copper ions from the coatings. The observation of antibacterial activity from a relatively low loading of copper on the bioactive HA support suggests that multifunctional implant coatings can be developed to supplement or supplant prophylactic antibiotics used in implant surgery that are responsible for creating resistant bacteria strains.

Synthesis and in-vitro antibacterial properties of a functionally graded Ag impregnated composite surface

Silver is considered promising in medical devices to prevent infection due to its excellent properties of broad antibacterial spectrum and persistent antibacterial activity. Herein, silver impregnated functionally graded composite surfaces have been developed by a novel duplex plasma deposition technique, which combines the double glow sputtering process and active screen plasma nitriding process. The composite surfaces include a surface antibacterial layer and a bottom supporting layer, which are deposited simultaneously. The functionally graded structure endows the composite surfaces with antibacterial activity, combined with improved wear resistance. The multilayer structures were observed by scanning electron microscopy, and the graded distribution of silver and nitrogen was verified by glow discharge optical emission spectroscopy. X-ray diffraction and X-ray photoelectron spectroscopy were used to analyze the microstructures and chemical states of the components. Results from physical properties tests indicated that the composite surfaces have increased hardness, lower contact angles, excellent scratch resistance and wear resistance. The in-vitro antibacterial tests using the Gram-negative E. coli. NCTC 10418 also showed that over 99% of bacteria were killed after 5 h contacting with the composite surface.

Antibiotic-Free Cationic Dendritic Hydrogels as Surgical-Site-Infection-Inhibiting Coatings

A non-toxic hydrolytically fast-degradable antibacterial hydrogel is herein presented to preemptively treat surgical site infections during the first crucial 24 h period without relying on conventional antibiotics. The approach capitalizes on a two-component system that form antibacterial hydrogels within 1 min and consist of i) an amine functional linear-dendritic hybrid based on linear poly(ethylene glycol) and dendritic 2,2-bis(hydroxymethyl)propionic acid, and ii) a di-N-hydroxysuccinimide functional poly(ethylene glycol) cross-linker. Broad spectrum antibacterial effect is achieved by multivalent representation of catatonically charged β-alanine on the dendritic periphery of the linear dendritic component. The hydrogels can be applied readily in an in vivo setting using a two-component syringe delivery system and the mechanical properties can accurately be tuned in the range equivalent to fat tissue and cartilage (G' = 0.5-8 kPa). The antibacterial effect is demonstrated both in vitro toward a range of relevant bacterial strains and in an in vivo mouse model of surgical site infection.

Multifunctional sulfonated polyetheretherketone coating with beta-defensin-14 for yielding durable and broad-spectrum antibacterial activity and osseointegration

To address periprosthetic joint infection (PJI), a formidable complication after joint arthroplasty, an implant with excellent osseointegration and effective antibacterial activity has being extensively pursued and developed. In this work, the mouse beta-defensin-14 (MBD-14) was immobilized on the polyetheretherketone (PEEK) surface with three-dimensional (3D) porous structure to improve its antibacterial activity and osseointegration. An in vitro antibacterial evaluation showed that the porous PEEK loaded with MBD-14 wages a durable and effective fight against both Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative). In addition to the superior antibacterial activity, we found that the enhanced proliferation and osteogenic differentiation of bone mesenchymal stem cells were verified through various in vitro analyses. To evaluate the in vivo bactericidal effect and osseointegration of the samples, the rat femoral models with infection and non-infection were established. The enhanced osseointegration of the MBD-14-loaded samples was found in both two in vivo models. And no bacteria survived on the surfaces of samples with a relatively high MBD-14 concentration. Above results indicate that the 3D porous PEEK coating loaded with MBD-14 simultaneously yields excellent osseointegration while exerting durable and broad-spectrum antibacterial activity. And it paves the way for PEEK to be applied clinically to address PJI. STATEMENT OF SIGNIFICANCE: (1). By using the physio-chemical technique including sulfonation and lyophilization etc., a three-dimensional porous network is developed on polyetheretherketone (PEEK) surface, in which mouse beta-defensin-14 (MBD-14, a broad-spectrum antimicrobial peptide) is then loaded. It endows PEEK with antibacterial activity and osseointegration. (2). Two in vivo animal models with infection and non-infection are used to prove the new bone formation around the samples. (3). Supplementary material also proves that MBD-14 promotes the osteogenic differentiation of BMSCs. However, its potential mechanism needs to be further studied in future. (4). The modified PEEK, including excellent osseointegration and a durable and broad-spectrum antibacterial activity, could be applied clinically to address PJI which is a hot potato for surgeons and patients undergoing total joint arthroplasty.

Chromium Cross-Linking Based Immobilization of Silver Nanoparticle Coating on Leather Surface with Broad-Spectrum Antimicrobial Activity and Durability

Leather with durable and broad-spectrum antimicrobial properties is very attractive in applications to produce diabetic shoes. In this work, gallic acid stabilized silver nanoparticles (GA@AgNPs) were prepared as water-borne finishing agent to be spray-coated on leather surface, with subsequent immobilization onto skin collagen via chromium(III) cross-linking. Such chemical anchoring of AgNPs onto microscaled collagen fibers not only enhanced the hydrophobicity of leather surface but also converted the surface ζ-potential from a positive charge to a negative charge, resulting in the excellent microbial antiadhesive ability of GA@AgNP-coated leather because of its dual-hydrophobic and electrostatic repelling of microbial adhesion. Such GA@AgNP coating also exhibited broad-spectrum antimicrobial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant S. aureus, and Candida albicans, with killing efficiencies all higher than 99%. Moreover, the killed microbes could be easily released from this anionic GA@AgNP spray coating by simply washing, preserving, and giving long-term antimicrobial activity to leather products. Most of all, the robust immobilization of AgNPs guaranteed the durably antimicrobial activity of such GA@AgNP-coated leather against laundry, perspiration, and mechanical abrasion in real daily use.

Poly(Alkyl Glycidate Carbonate)s as Degradable Pressure-Sensitive Adhesives

Insertion of CO₂ into the polyacrylate backbone, forming poly(carbonate) analogues, provides an environmentally friendly and biocompatible alternative. The synthesis of five poly(carbonate) analogues of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate) is described. The polymers are prepared using the salen cobalt(III) complex catalyzed copolymerization of CO₂ and a derivatized oxirane. All the carbonate analogues possess higher glass-transition temperatures (T_g =32 to -5 °C) than alkyl acrylates (T_g =10 to -50 °C), however, the carbonate analogues (T_d ≈230 °C) undergo thermal decomposition at lower temperatures than their acrylate counterparts (T_d ≈380 °C). The poly(alkyl carbonates) exhibit compositional-dependent adhesivity. The poly(carbonate) analogues degrade into glycerol, alcohol, and CO₂ in a time- and pH-dependent manner with the rate of degradation accelerated at higher pH conditions, in contrast to poly(acrylate)s.

A hydrogel directly assembled from a copper metal–organic polyhedron for antimicrobial application

A hydrogel was directly assembled from a Cu-MOP by a facile procedure without adding any polymers for the first time, and it exhibited excellent antibacterial activity towards both Gram-negative and Gram-positive bacteria.

Mussel-inspired coatings with tunable wettability, for enhanced antibacterial efficiency and reduced bacterial adhesion

The mussel-inspired coatings with tunable wettability were designed, showing enhanced antibacterial efficiency and reduced bacterial adhesion.

Molybdenum sulfide Co-catalytic Fenton reaction for rapid and efficient inactivation of Escherichia coli

As a typical advanced oxidation technology, the Fenton reaction has been employed for the disinfection, owing to the strong oxidizability of hydroxyl radicals (·OH). However, the conventional Fenton system always exhibits a low H₂O₂ decomposition efficiency, leading to a low production yield of ·OH, which makes the disinfection effect unsatisfactory. Herein, we develop a molybdenum sulfide (MoS₂) co-catalytic Fenton reaction for rapid and highly efficient inactivation of Escherichia coli K-12 (E. coli) and Staphylococcus aureus (S. aureus). As a co-catalyst in the Fe(II)/H₂O₂ Fenton system, MoS₂ can greatly facilitate the Fe(III)/Fe(II) cycle reaction by the exposed Mo⁴⁺ active sites, which significantly improves the H₂O₂ decomposition efficiency for the ·OH production. As a result, the MoS₂ co-catalytic Fenton system can reach up to 83.37% of inactivation rate of E. coli just in 1 min and 100% of inactivation rate within 30 min, which increased by 2.5 times than that of the conventional Fenton reaction. Furthermore, the ·OH as the primary reactive oxygen species (ROS) in MoS₂ co-catalytic Fenton reaction was measured and verified by electron paramagnetic resonance (EPR) and photoluminescence (PL). It is demonstrated an increased amount of ·OH generated from the decomposition of H₂O₂ in the presence of MoS₂, which is responsible for the rapid and efficient inactivation of E. coli and S. aureus. This study provides a new perspective for rapid and highly efficient inactivation of bacteria in environmental remediation.

CuO Nanoparticles-Containing Highly Transparent and Superhydrophobic Coatings with Extremely Low Bacterial Adhesion and Excellent Bactericidal Property

Human health and industrial instruments have been suffering from bacterial colonization on the surface of materials for a long time. Recently, antibacterial coatings are regarded as the new strategy to resist bacterial pathogens. In this work, novel highly transparent and superhydrophobic coatings with extremely low bacterial adhesion and bactericidal performance were prepared by spray-coating hydrophobic silica sol and CuO nanoparticles. The coated glass showed high transmittance in 300-2500 nm with a maximum value of 96.6%. Compared with bare glass, its superhydrophobic characteristics resulted in a reduction in adhesion of bacteria ( Escherichia coli, E. coli) by up to 3.2 log cells/cm². Additionally, the live/dead staining test indicated that the as-prepared coating exhibited excellent bactericidal performance against E. coli. Moreover, the as-prepared coating could maintain their superhydrophobicity after the sand impact test. The proposed method to fabricate such coatings could be applied on various substrates. Therefore, this novel hybrid surface with the abilities to reduce bacterial adhesion and kill attached bacteria make it a promising candidate for biosensors, microfluidics, bio-optical devices, household facilities, lab-on-chips, and touchscreen devices.

Near-Infrared Light-Activated Thermosensitive Liposomes as Efficient Agents for Photothermal and Antibiotic Synergistic Therapy of Bacterial Biofilm

Biofilm is closely related to chronic infections and is difficult to eradicate. Development of effective therapy strategies to control biofilm infection is still challenging. Aiming at biofilm architecture, we designed and prepared near-infrared-activated thermosensitive liposomes with photothermal and antibiotic synergistic therapy capacity to eliminate Pseudomonas aeruginosa biofilm. The liposomes with positive charge and small size aided to enter the biofilm microchannels and locally released antibiotics in infection site. The liposomes could remain stable at 37 °C and release about 80% antibiotics over 45 °C. The biofilm dispersion rate was up to 80%, which was a 7- to 8-fold rise compared to excess antibiotic alone, indicating that the localized antibiotic release and photothermal co-therapy improved the antimicrobial efficiency. In vivo drug-loaded liposomes in treating P. aeruginosa-induced abscess exhibited an outstanding therapeutic effect. Furthermore, photothermal treatment could stimulate the expression of bcl2-associated athanogene 3 to prevent normal tissue from thermal damage. The near-infrared-activated nanoparticle carriers had the tremendous therapeutic potential to dramatically enhance the efficacy of antibiotics through thermos-triggered drug release and photothermal therapy.

Emerging Nanomedicine Therapies to Counter the Rise of Methicillin-Resistant Staphylococcus aureus

In a recent report, the World Health Organisation (WHO) classified antibiotic resistance as one of the greatest threats to global health, food security, and development. Methicillin-resistant Staphylococcus aureus (MRSA) remains at the core of this threat, with persistent and resilient strains detectable in up to 90% of S. aureus infections. Unfortunately, there is a lack of novel antibiotics reaching the clinic to address the significant morbidity and mortality that MRSA is responsible for. Recently, nanomedicine strategies have emerged as a promising therapy to combat the rise of MRSA. However, these approaches have been wide-ranging in design, with few attempts to compare studies across scientific and clinical disciplines. This review seeks to reconcile this discrepancy in the literature, with specific focus on the mechanisms of MRSA infection and how they can be exploited by bioactive molecules that are delivered by nanomedicines, in addition to utilisation of the nanomaterials themselves as antibacterial agents. Finally, we discuss targeting MRSA biofilms using nano-patterning technologies and comment on future opportunities and challenges for MRSA treatment using nanomedicine.

Strategies to prevent the occurrence of resistance against antibiotics by using advanced materials

Drug resistance occurrence is a global healthcare concern responsible for the increased morbidity and mortality in hospitals, time of hospitalisation and huge financial loss. The failure of the most antibiotics to kill "superbugs" poses the urgent need to develop innovative strategies aimed at not only controlling bacterial infection but also the spread of resistance. The prevention of pathogen host invasion by inhibiting bacterial virulence and biofilm formation, and the utilisation of bactericidal agents with different mode of action than classic antibiotics are the two most promising new alternative strategies to overcome antibiotic resistance. Based on these novel approaches, researchers are developing different advanced materials (nanoparticles, hydrogels and surface coatings) with novel antimicrobial properties. In this review, we summarise the recent advances in terms of engineered materials to prevent bacteria-resistant infections according to the antimicrobial strategies underlying their design.