Antifouling Properties Research Articles

Impact of titanium dioxide/graphene in polyvinylidene fluoride nanocomposite membrane to intensify methylene blue dye removal, antifouling performance, and reusability

AbstractThe development of efficient water purification technologies is a critical research focus driven by the crucial role of clean water sources for ecological sustainability. This study explores the strategic incorporation of nanoparticles within polyvinylidene fluoride (PVDF) membranes as a promising approach to enhance membrane performance for wastewater remediation. PVDF membranes containing varying ratios of graphene (GR) and titanium dioxide (TiO2) nanocomposites were fabricated via phase inversion method. Characterization techniques including XRD, FTIR, and FESEM‐EDX revealed that the 80% GR nanocomposite membrane exhibited desirable structural and functional properties with pronounced sponge‐like morphology and homogenous nanoparticle distribution. Fourier‐transform infrared spectroscopy and x‐ray diffraction analysis confirmed the 80% GR membrane retained PVDF crystallinity while uniquely eliminating TiO2 crystallinity. Subsequently, performance testing demonstrated the 80% GR nanocomposite membrane had the highest water flux and methylene blue dye rejection rates compared to other ratios and the pristine PVDF membrane. Both fabricated membranes exhibited sufficient reusability and antifouling properties. However, 80% GR ratio exhibited superior antifouling properties, indicating its potential as an optimal material for improving membrane hydrophilicity and overall water purification technologies. These findings underscore the strategic utility of GR‐TiO2 nanocomposites for enhancing PVDF membrane performance in sustainable wastewater treatment applications.

Enhanced Anticorrosion, Antifouling, and Tribological Properties of PANI Composite Coating Reinforced by PVA, 2-Aminophenol, and Acrylic to Fabricate Sustainable Passive Film on 304 SS

Enhanced Anticorrosion, Antifouling, and Tribological Properties of PANI Composite Coating Reinforced by PVA, 2-Aminophenol, and Acrylic to Fabricate Sustainable Passive Film on 304 SS

Fabrication and characterization of poly(methyl vinyl ether maleic anhydride) blended poly(lactic acid) ultrafiltration membrane with upgraded antifouling and separation performance

In this present study, a novel environment-friendly bio-polymeric hybrid ultrafiltration membrane was fabricated by incorporating poly(methyl vinyl ether maleic anhydride) (PMVEAMA) into the poly(lactic acid) (PLA) polymer matrix. The integration of PMVEAMA into PLA significantly altered the membrane's structural morphology, functional characteristics, and filtration performance. As a result, key functional parameters like membrane porosity and water content were increased, which exhibiting the improved hydrophilicity. Furthermore, the molecular weight cut-off of the PLA/PMVEAMA membrane reached up to a maximum of 66.5 KDa with an average pore size of 9.14 nm, subsequently improving the flux of the membrane up to 2.8 times than PLA membrane. The functional capacity of the synthesized membrane was further assessed by testing its ability to filter toxic chlorophenolic compounds. Rejection studies reveal that the PLA/PMVEAMA membrane achieved a rejection efficiency of 44.64 % pentachlorophenol (PCP) and 51.85 % 2,4-dichlorophenol (DCP). Moreover, fouling studies revealed enhanced PCP and DCP flux recovery ratios of 50.94 % and 51.40 %, respectively, with a significant reduction in the flux decline rate. Additionally, the synthesized PLA/PMVEAMA membranes improved stability and regenerative properties up to 12 filtration cycles and antifouling properties highlight its potential to filter chlorophenolic compounds from wastewater.

Rapid assembly of mixed thiols for toll-like receptor-based electrochemical pathogen sensing.

Herein, we describe a rapid and facile fabrication of electrochemical sensors utilizing two different toll-like receptor (TLR) proteins as biorecognition elements to detect bacterial pathogen associated molecular patterns (PAMPs). Using potential-assisted self-assembly, binary mixtures of 11-mercaptoundecanoic acid (MUA) and 6-mercapto-1-hexanol (MCH), or MUA and an in-house synthesized zwitterionic sulfobetaine thiol (DPS) were assembled on a gold working electrode within 5 minutes, which is >200 times shorter than other TLR sensors' preparation time. Electrochemical methods and X-ray photoelectron microscopy were used to characterize the SAM layers. SAMs composed of the betaine terminated thiol exhibited superior resistance to nonspecific interactions, and were used to develop the TLR sensors. Biosensors containing two individually immobilized TLRs (TLR4 and TLR9) were fabricated on separate MUA-DPS SAM modified Au electrodes (MUA-DPS/Au) and tested for their response towards their respective PAMPs. The changes to electron transfer resistance in EIS of the TLR4/MUA-DPS/Au sensor showed a detection limit of 4 ng mL-1 for E. coli 0157:H7 endotoxin (lipopolysaccharide, LPS) and a dynamic range of up to 1000 ng mL-1. The TLR4-based sensor showed negligible response when tested with LPS spiked human plasma samples, showing no interference from the plasma matrix. The TLR9/MUA-DPS/Au sensor responded linearly up to 350 μg mL-1 bacterial DNA, with a detection limit of 7 μg mL-1. The rapid assembly of the TLR sensors, excellent antifouling properties of the mixed SAM assembly, small size and ease of operation of EIS hold great promise for the development of a portable and automated broad-spectrum pathogen detection and classification tool.

Forward osmosis membrane with lightweight functionalised multiwall carbon nanotube nanofillers

ABSTRACT Thin-film nanocomposite (TFN) membranes with a polyamide (PA) active layer modified with carbon nanotubes (CNTs) hold promise for water desalination and wastewater reuse via forward osmosis (FO). We hypothesise that modifying the PA active layer with hydroxyl-functionalised multi-wall carbon nanotubes (f-MWCNTs) will enhance the water flux of the FO membrane while maximising salt rejection. TFN membranes were modified using in situ interfacial polymerisation, with varying f-MWCNT mass content to minimise agglomeration. These modified FO membranes are designated as CTFN-x, where x represents the mass content of f-MWCNTs, ranging from 0.001%, CTFN-1 to 0.008%, CTFN-8 (w/v). The surface properties of CTFN-x were characterised using electron microscopy, atomic force microscopy, and molecular spectroscopy. IR spectroscopic data confirm the successful adherence of f-MWCNTs as a bridging agent between the 1,3-phenylenediamine (MPD) and trimesoyl chloride (TMC) polymers, preserving FO membrane integrity. The CTFN-4 FO membrane shows the highest water flux (29 LMH) and the lowest reverse salt flux (2.90 gHM), attributed to preferential water flow channels in the f-MWCNTs. The integration of f-MWCNTs into the active layer improved water flux, reduced reverse salt flux, and enhanced the antifouling properties of FO membranes.

Coupling effects of micro/nano-scale surface modification and electric current application on fouling resistance and heat transfer

The principle of saving energy and converting waste heat into valuable resources is a core concept. Heat exchange systems are significantly compromised by microbial fouling, which impedes heat transfer and increases energy consumption. This study investigated the coupling effects of micro/nano-scale surface modifications and the application of electric currents as a novel approach to inhibit microbial fouling. Smooth copper surface, electrochemical deposition (ECD) surface, and Nickel-Phosphorus-Polytetrafluoroethylene (Ni-P-PTFE) modified surface were tested and compared. Firstly, we analyzed the average heat transfer coefficient under clean conditions, taking into account different surface characteristics. Then, we employed a series of fouling experiments to evaluate the anti-biofouling performance of smooth copper surfaces, ECD surfaces, and Ni-P-PTFE surfaces. The assessment involved flow cytometry, Scanning Electron Microscopy (SEM) and measurements of thermal resistance. Finally, we investigated the effect of external electric current on microbial fouling mitigation. Results show that the ECD surface exhibited an enhanced heat transfer and a poor fouling resistance, while the Ni-P-PTFE surface demonstrated an excellent fouling resistance and a minimal increase in thermal resistance. The application of a low direct current density at 0.51 mA/cm² significantly reduced microbial viability on all surfaces. A higher electric current can further inhibit microbial adhesion and proliferation, enhancing the anti-fouling capability of the surfaces. Compared to surfaces without electric current, the smooth copper surface, ECD, and Ni-P-PTFE surfaces at 5.1 mA/cm² displayed a reduction in thermal resistance by 45.7%, 36.8%, and 38.1%, respectively. At 51 mA/cm², the reduction in thermal resistance for smooth copper surface, ECD, and Ni-P-PTFE surfaces was 75.7%, 78.2%, and 57.1%, respectively. This comprehensive study has validated the potential of combining micro/nano-scale surface modifications with electric current application as an effective strategy for enhancing heat transfer efficiency and anti-fouling properties of heat exchange systems.

Synthesis of Antifouling Poly(ethylene glycol) Brushes via "Grafting to" Approach for Improved Biodistribution.

Polyethylene glycol (PEG) modification of materials has been identified to mitigate the challenge of biofouling. However, the practical application of PEGylation has been hampered by a low PEGylation density on the material surface. Therefore, developing efficient strategies to promote the PEGylation density is crucial. In this study, PEG brushes (PBs) with various structures were synthesized and their physicochemical properties and biomedical applications were investigated. Compared to benzaldehyde (BA), o-phthalaldehyde (OPA) exhibited higher reactivity with amine groups, resulting in increased grafting density (as high as 96.3%) and improved antifouling properties of PEG brushes. Bottlebrushes fabricated by PEG-OPA and polylysine demonstrated a prolonged circulation time in blood and enhanced potential for magnetic resonance imaging of tumors. Furthermore, the rigidity of the backbone was found to be crucial for the antifouling properties of PEG brushes both in vitro and in vivo. These findings are significant and provide valuable insights into designing biomaterials with superior antifouling performance.

Bifunctionalized MOFs modified poly (aryl ether ketone sulfone) ultrafiltration membranes with high-efficient BSA separation and dye adsorption

In this study, by connecting the amino ligand in ZIF-8-NH2 with an alkyl side chain containing sulfonic acid groups in a one-step method, a novel nanofiller (ZIF-8-NS) with bifunctional amino and sulfonic acid groups was formed. Sulfonated poly (aryl ether ketone sulfone) containing fluorene group (F-SPAEKS) was chosen as the polymer matrix. The nanofiller not only had good hydrophilicity but also had electrostatic interaction with the polymer matrix, which effectively promoted the compatibility problem among the polymer matrix and the filler. The nanofillers were characterized by XRD, FT-IR, SEM and XPS. The composite membranes were prepared by the NIPs method. The antifouling and separation properties of the prepared mixed matrix membranes (MMMs) were investigated using positively charged dye (RHB) and negative charge bovine serum albumin (BSA) as model contaminants. The water flux of the pure membrane achieved 529.16 L/m2 h. When the addition amount of ZIF-8-NS was 0.1 %, the water flux of M4 (F-SPAEKS/ZIF-8-NS-0.1 %) could reach 838.84 L/m2 h. The retention rate of the BSA solution could reach 99.06 %, and the FRR value was kept at a high level (81.45 %). Meanwhile, the dynamic retention of M4 on the primary adsorption of the dye RHB could even reach 99.89 %. Therefore, the innovative design of the novel MMMs not only improved the flux, retention, and other separation properties but also enhanced their excellent adsorption capacity for RHB dyes. This result indicated that the nanofiller ZIF-8-NS provided an interesting reference for the study of ultrafiltration membranes.

Cross-linked copolyimide-P84/CAU-10-H/branched polyethyleneimine membranes for organic solvent nanofiltration

The advancement of organic solvent nanofiltration (OSN) is often hindered by the inherent trade-off between permeance and rejection. In this study, we present a novel nanocomposite mixed matrix membrane (MMM) fabricated by integrating a compatible metal–organic framework (CAU-10-H) into a co-polyimide (P84) matrix. The resulting P84/CAU-10-H membrane was cross-linked using branched polyethyleneimine (PEI) to produce a P84/CAU-10-H/PEI MMM with robust resistance to harsh organic solvents, making it suitable for OSN applications. The integration of CAU-10-H, PEI, and P84 significantly enhanced the OSN performance, improving sieving efficiency and reducing fouling tendencies. The fabricated membrane exhibited outstanding permeance across various solvents, with values of 42.4, 45.4, 24.5, and 27.1 LMH/bar for methanol, acetone, N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO), respectively. Besides, the P84/CAU-10-H/PEI MMM demonstrated excellent rejection (Brilliant yellow (BY) > 90 %, Congo red (CR), Methyl blue (MB), Evans blue (EB), and Alcian blue (AB) > 99 %, respectively). In a 96-hour long-term test, the membrane demonstrated excellent stability and anti-fouling properties. This study presents a facile and viable approach for designing and constructing novel OSN MMMs.

Development of high flux photocatalytic agcl-cooh-mwcnt/pes ultrafiltration membranes for enhanced waste water treatment and fouling mitigation

A structurally stable AgCl-COOH MWCNT/PES composite membrane was designed and fabricated by combining phase conversion and post-treatment techniques, which can solve the serious membrane fouling in industrial wastewater treatment. The carboxylation of MWCNTs not only enhanced their dispersion but also facilitated their binding with silver chloride, resulting in a stable composite structure that significantly improved contaminant degradation capabilities. The post-treatment technique increased the membrane’s water purification flux by 150 % (reaching 520 L·m2·h−1·bar−1) while maintaining a high BSA retention rate of 95 %. Additionally, the composite membrane demonstrated excellent photocatalytic antifouling properties, with a flux recovery rate of 91.8 % under UV irradiation, and exhibited more than 99 % inhibition of Escherichia coli. This method provides a scalable solution for enhancing the performance of PES membranes in wastewater treatment applications.

Redox Concomitant Formation Method for Fabrication of Cu(I)-MOF/Polymer Composites with Antifouling Properties.

Marine biofouling, which is one of the technical challenges hindering the growth of the marine economy, has been controlled using cuprous oxide (Cu2O) nanoparticles due to the exceptional antifouling properties of Cu(I) ions. However, Cu2O nanoparticles have encountered bottlenecks due to explosive releases of Cu+ ions, high toxicity at elevated doses, and long-term instability. Here, we present a novel method called Redox Concomitant Formation (RCF) for fabricating a hierarchical Cu(I) metal-organic framework polypyrrole (Cu(I)-MOF/PPy) composite. This method enables in-situ phase transition via successive redox reactions that change the chemical valence state and coordination mode of Cu(II)-MOF, resulting in a new structure of Cu(I)-MOF while creating a PPy layer surrounded by the hierarchical structure. Owing to the steady release of Cu+ ions from the Cu(I) sites and photothermal properties of PPy, Cu(I)-MOF/PPy exhibits superior and broad-spectrum resistance to marine bacteria, algae, and surface-adhered biofilms in complex biological environments, as well as long-term stability, resulting in 100% eradication efficiency under solar-driven heating. Mechanistic insights into successive structural redox reactions and formation using the RCF method are provided in detail, enabling the fabrication of novel MOFs with the desired composition and structure for a wide range of potential applications.

Redox Concomitant Formation Method for Fabrication of Cu(I)−MOF/Polymer Composites with Antifouling Properties

AbstractMarine biofouling, which is one of the technical challenges hindering the growth of the marine economy, has been controlled using cuprous oxide (Cu2O) nanoparticles due to the exceptional antifouling properties of Cu(I) ions. However, Cu2O nanoparticles have encountered bottlenecks due to explosive releases of Cu+ ions, high toxicity at elevated doses, and long‐term instability. Here, we present a novel method called Redox Concomitant Formation (RCF) for fabricating a hierarchical Cu(I) metal–organic framework polypyrrole (Cu(I)−MOF/PPy) composite. This method enables in situ phase transition via successive redox reactions that change the chemical valence state and coordination mode of Cu(II)−MOF, resulting in a new structure of Cu(I)−MOF while creating a PPy layer surrounded by the hierarchical structure. Owing to the steady release of Cu+ ions from the Cu(I) sites and photothermal properties of PPy, Cu(I)−MOF/PPy exhibits superior and broad‐spectrum resistance to marine bacteria, algae, and surface‐adhered biofilms in complex biological environments, as well as long‐term stability, resulting in 100 % eradication efficiency under solar‐driven heating. Mechanistic insights into successive structural redox reactions and formation using the RCF method are provided in detail, enabling the fabrication of novel MOFs with the desired composition and structure for a wide range of potential applications.

In-situ confined preparation of COF@GO nanofiltration membranes for high-efficiency dye removal

Graphene oxide membrane (GOM) possesses ultrafast and tunable two-dimensional water transport pathways, making it an ideal candidate for nanofiltration separation of dye wastewater. However, GOM also faces great challenges such as poor aqueous stability, collapse of non-oxygenated regions under high pressure, and limitations imposed by trade-off effects. In this study, covalent organic frameworks (COFs) were in-situ formed within GOM interlayers and on membrane surface to enlarge interlayer spacings and enhance hydrophilicity of GOM simultaneously via a two-step method including monomer retention in GOM and in-situ confined interfacial polymerization of COFs. Fourier transformation infrared spectroscopy (FT-IR) and X-ray photoelectron spectrometry (XPS) results confirmed the successful synthesis of COF on GOM surface, which enhanced membrane surface hydrophilicity and bridged the split defects of GOM. According to X-ray diffraction measurements (XRD) and scanning electron microscope (SEM) results, COF@GO membranes possessed enlarged interlayer spacings and increased thickness of selective layer, which indicated the successful intercalation of COF into GO interlayer. COF@GO-50 membrane exhibited an ultrahigh pure water permeability (PWP) of 148.1 L/(m2·h·bar), with 99.0 % rejection for direct red 80 (DR80) aqueous solution and 9.6 % NaCl rejection. The ultrahigh water permeance might be ascribed to the enlarged interlayer pathways, the shortened vertical pathways provided by in-plane pores of COF nanosheets, and enhanced water adsorption capacity due to enhanced membrane hydrophilicity. Moreover, COF@GO nanofiltration membrane demonstrated excellent anti-fouling properties and long-term stability in 30h continuous operation, maintaining considerable separation efficiency under harsh conditions. This work provides a straightforward and applicable strategy to simultaneously enlarge interlayer spacings and enhance surface hydrophilicity of GOM via in-situ confined preparation of COFs, achieving ultrahigh water permeance and overcoming the trade-off effect between permeability and selectivity of GOM.

Performance regulation of the TFC NF membrane via the introduction of oleic acid into different organic solvents

AbstractBACKGROUNDTailored design of high‐performance nanofiltration membranes is desirable. The physicochemical properties of the organic phaseare essential for the preparation of nanofiltration membranes. Therefore, byfine‐tuning the organic phase, it is possible to achieve nanofiltrationmembranes with enhanced performance.RESULTSIn this work, oleic acid, a naturally extracted fatty acid, wasintroduced into three different organic solvents (n‐heptane, n‐octane andisopar G) to construct special oil phases for interfacial polymerization. Testingresults showed that proper dosage of oleic acid addition can effectivelydecrease the nanofiltration membrane pore size and enhance the salt rejectionregardless of the solvent type. Taking n‐octane as example, 5% oleic acidaddition in it can decrease the mean pore size from 0.500 nm to 0.341 nm and improve the MgSO4 rejection from 52.4% to 95.5%. Further characterizationindicated that the introduction of oleic acid into organic solvent cansignificantly reduce the interfacial tension and promote the diffusion of piperazinefrom aqueous phase to the oil phase. In addition, oleic acid could react with piperazineand produce some white particles that could be embed into the polyamide layer, thus altering the surface morphology.CONCLUSIONIn this work, a novel modified thin film composite nanofiltration membrane was prepared by a simple and controllable oleic acid assisted interfacial polymerization strategy, which exhibits good water permeability, solute selectivity and antifouling property. Without changing the existing process, our strategy opens up a simple, environmentally friendly and operable route for the synthesis of thin film composite nanofiltration membranes. © 2024 Society of Chemical Industry (SCI).

CuO-Fe3C-C modified PVDF membrane for catalysis and antifouling

Modification of membranes is an effective method for degrading organic pollutants and alleviating membrane fouling. In this study, CuO-Fe3C-C catalyst was prepared by high-temperature pyrolysis. The membrane modified by CuO- Fe3C-C was prepared by vacuum filtration. The bacteriostatic rate of the modified membrane can reach to 96.8 %. Compared to the pristine membrane, the pure water flux of the modified membrane increased from 223.43 L m−2h−1 bar−1 to 422.27 L m−2h−1 bar−1, the flux recovery ratio (FRR) of modified membranes increased from 39.7 % to 79.25 %. Removal rate of TC (Tetracycline) by modified membrane activated PMS can reach to 90.75 %. After 5 cycles, the degradation efficiency of modified membranes was still 83.77 %, which was only 6.39 % lower than that of the first cycle. Free radical quenching experiments and ESR tests explored the possible catalysis and antifouling mechanisms of the modified membrane system, the results showed main active species were SO4−•, OH•, O2−• and 1O2. This study prepared membranes with excellent antifouling properties, providing a theoretical reference for alleviating membrane fouling in membrane-based water treatment.

Novel fluorine-functionalized Ti3C2Tx/TiO2 hybrid coatings with enhanced weatherability, antifouling, and interfacial anticorrosion performances

As a valuable symbol of human cultural heritage, bronze inevitably endures varying degrees of corrosion due to environmental change. Thus, developing an efficient protective coating for bronze is crucial to ensure bronze relics receive more protection. Herein, a multifunctional organic-inorganic hybrid composite coating of 1 H,1 H,2 H,2 H-Perfluorodecyltriethoxysilane (PFDTES), Ti3C2Tx nanosheets and TiO2 nanoparticles (PFDTES@Ti3C2Tx/TiO2) are successfully prepared and coated the bronze, which exhibits excellent anti-corrosion, weathering stability and superhydrophobicity. The superhydrophobicity of coating is derived from introducing a low surface energy C-F bond. Furthermore, the corrosion protection ability can be improved by the barrier effect of Ti3C2Tx nanosheets, and TiO2 nanoparticles can enhance the weathering stability of coatings by providing exceptional abrasion resistance and ultraviolet (UV) resistance capabilities. Morphological examination, X-ray photoelectron spectroscopy, an accelerated aging test, and electrochemical measurements, among other methods, were used to research the protective effect and anticorrosion performance of organic-inorganic hybrid coatings. It can be found that the composite coatings have a large water contact angle (153°) and form a superhydrophobic surface. Furthermore, electrochemical results show that the superhydrophobic PFDTES@Ti3C2Tx/TiO2 coating has a higher low-frequency impedance modulus and lower current density than the uncoated substrate, indicating enhanced corrosion resistance. Based on solid and liquid pollutant tests, the PFDTES@Ti3C2Tx/TiO2 coatings also showed good self-cleaning and antifouling properties. And coating maintained good transparency without changing the bronze color and appearance. In conclusion, the superhydrophobic PFDTES@Ti3C2Tx/TiO2 composite coating has potential applications in the field of bronze protection.

An environmentally friendly coating: Excellent self-cleaning, efficient antimicrobial, and durability properties

The development of non-polluting and non-toxic polymer antimicrobial agents is a prominent focus in contemporary research and development. Polymer quaternary ammonium salts are particularly promising for their antimicrobial efficacy. In this study, we synthesized quaternary imidazole derivatives using butylimidazole and 3-chloropropyltriethoxysilane. We then prepared PDMS/BIS/PPS hydrophobic antimicrobial composite coatings by incorporating quaternary ammonium salt chemically grafted silica (BIS), polyphenylene sulfide (PPS), and polydimethylsiloxane (PDMS). The resulting composite coating displayed a high contact angle of 136.4°±1° and a low sliding angle of less than 5°±1°, indicating its hydrophobic nature. Electrochemical assessments demonstrated exceptional corrosion resistance, with a corrosion inhibition rate of 99.967 %. Bacterial assays confirmed the coating's effectiveness in inhibiting bacterial proliferation, especially against E. coli. The quaternary ammonium-modified silica particles in the coating facilitate bacterial adsorption through electrostatic interactions, which compromise cell membrane permeability, obstruct nutrient uptake, and induce apoptosis. With its anti-fouling, self-cleaning, and anti-corrosion properties, this coating has substantial potential for applications in various fields, including medical devices, and food packaging.

Facile Surface Modification with Croconaine-Functionalized Polymer on Polypropylene for Antifouling and NIR-Light-Mediated Photothermal Sterilization.

Biomedical-device-associated infection (BAI) is undoubtedly a major concern and a serious challenge in modern medicine. Therefore, the development of biomedical materials that are capable of resisting or killing bacteria is of great importance. In this work, a croconaine-functionalized polymer with antifouling and near-infrared (NIR) photothermal bactericidal properties was prepared and facilely modified on polypropylene (PP) to combat medical device infections. Croconaine dye is elaborately modified as a "living" initiator, termed CR-4EBiB, for preparing amphiphilic block polymers by atom transfer radical polymerization (ATRP). In the formed polymer coating, the hydrophobic block can strongly adhere to the surface of the PP substrate, whereas the hydrophilic block is located on the outer layer by solvent-induced resistance to bacterial adhesion. Under the irradiation of an NIR laser (808 nm), the croconaine dye in the coating achieved maximum conversion of light to heat to effectively kill E. coli, S. aureus, and methicillin-resistant Staphylococcus aureus (MRSA). This work provides a facile and promising strategy for the development of implantable antibacterial biomedical materials.

Copper tannate nanosheets-embedded multifunctional coating for antifouling and photothermal bactericidal applications

Implant-associated infections (IAIs), triggered by pathogenic bacteria, are a leading cause of implant failure. The design of functionalized coatings on biomedical materials is crucial to address IAIs. Herein, a multifunctional coating with good antifouling effect and antibacterial photothermal therapy (aPTT) performance was developed. The copper tannate nanosheets (CuTA NSs) were formed via coordination bonding of Cu2+ ions and tannic acid (TA). The CuTA NSs were then integrated into the TA and poly(ethylene glycol) (PEG) network to form the TCP coating for deposition on the titanium (Ti) substrates via surface adhesion of TA and gravitational effect. The resulting Ti-TCP substrate exhibited good antifouling property, reactive oxygen species (ROS) scavenging capability and cytocompatibility. The TCP coating exhibited antifouling efficacy in conjunction with aPTT, curtailing the surface adhesion and biofilm formation of pathogens, such as Staphylococcus aureus and Escherichia coli. Notably, the Ti-TCP substrate also exhibited the ability to prevent bacterial infection in vivo in a subcutaneous implantation model. The present work demonstrated a promising approach in designing high-performance antifouling and photothermal bactericidal coatings to combat IAIs.

In-situ nanozyme catalytic amplification coupled with a universal antibody orientation strategy based electrochemical immunosensor for AD-related biomarker

An in-situ nanozyme signal tag combined with a DNA-mediated universal antibody-oriented strategy was proposed to establish a high-performance immunosensing platform for Alzheimer's disease (AD)-related biomarker detection. Briefly, a Zr-based metal-organic framework (MOF) with peroxidase (POD)-like activity was synthesized to encapsulating the electroactive molecule methylene blue (MB), and subsequently modified with a layer of gold nanoparticles on its surface. This led to the creation of double POD-like activity nanozymes surrounding the MB molecule to form a nanozyme signal tag. A large number of hydroxyl radicals were generated by the nanozyme signal tag with the help of H2O2, which catalyzed MB molecules in situ to achieve efficient signal amplification. Subsequently, a DNA-aptamer-mediated universal antibody-oriented strategy was proposed to enhance the binding efficiency for the antigen (target). Meanwhile, a poly adenine was incorporated at the end of the aptamer, facilitating binding to the gold electrode and providing anti-fouling properties due to the hydrophilicity of the phosphate group. Under optimal conditions, this platform was successfully employed for highly sensitive detection of AD-associated tau protein and BACE1, achieving limits of detection with concentrations of 3.34 fg/mL and 1.67 fg/mL, respectively. It is worth mentioning that in the tau immunosensing mode, 20 clinical samples from volunteers of varying ages were analyzed, revealing significantly higher tau expression levels in the blood samples of elderly volunteers compared to young volunteers. This suggests that the developed strategy holds great promise for early AD diagnosis.