Effects of flow-induced electromagnetic field and surface roughness on antifouling activity of phenolic compounds.

Microbial fouling involves the physicochemical interactions between microorganisms and solid surfaces. An electromagnetic field (EMF) may change the diffusion rates of microbial cells and the electrical double layer around the cells and contacting surfaces. In the current study, polycardanol exhibiting antibiofouling activity was modified with ferromagnetic iron oxide (IO) to investigate the EMF effects on bacterial adhesion. When there was a flow of electrolyte that contained bacterial cells, flow-induced EMF was generated according to Faraday's principle. It was observed that the IO-ionic solution (IS)-modified surfaces, with an induced current of 44, 53, 66 nA, showed decreases in the adhesion of bacteria cells more than the unmodified (polycardanol) and IO-nanoparticles-modified ones. In addition to the EMF effects, the nano-scale uniform roughness of the modified surfaces appeared to play an important role in the reduction of cell adhesion. The results demonstrated that the IOIS-modified surface (3.2 × 10-6 mM IO) had the highest antibiofouling activity.

Cyclodextrin-modified PVDF membranes with improved anti-fouling performance.

The design of hydrophilic polyvinylidene fluoride (PVDF) membranes with anti-fouling properties has been explored for decades. Surface modification and blending are typical strategies to tailor the hydrophilicity of PVDF membranes. Herein, cyclodextrin was used to improve the antifouling performance of PVDF membranes. Cyclodextrin-modified PVDF membranes were prepared by coupling PVDF amination (blending with branched polyethyleneimine) and activated cyclodextrin grafting. The blending of PEI in the PVDF casting solution preliminarily aminated the PVDF, resulting in PEI-crosslinked/grafted PVDF membranes after phase inversion. Aldehydes groups on cyclodextrin, introduced by oxidation, endow cyclodextrin to be grafted on the aminated PVDF membrane by the formation of imines. Borch reduction performed on the activated cyclodextrin-grafted PVDF membrane converted the imine bonds to secondary amines, ensuring the membrane stability. The resulting membranes possess excellent antifouling performance, with a lower protein adsorption capacity (5.7 µg/cm2, indicated by Bovine Serum Albumin (BSA)), and a higher water flux recovery rate (FRR=96%). The proposed method provides a facial strategy to prepare anti-fouling PVDF membranes.

One-Step Phase Separation and Mineralization Fabrication of Membranes for Oily Wastewater Treatment.

Oily wastewater threatens the environment and the human health. Membrane technology offers a simple and efficient alternative to separating oil and water. However, complex membrane modifications are usually employed to optimize the separation performance. In this research, we develop an extremely simple one-step method to in situ calcium carbonate (CaCO3) nanoparticles onto a porous polyketone (PK) membrane via a nonsolvent induced phase separation (NIPS)-mineralization strategy. We utilized the unique chemical property of PK, which allows it to dissolve in a resorcinol aqueous solution. PK was mixed with tannic acid (TA) and calcium chloride (CaCl2) in a resorcinol aqueous solution to fabricate a casting solution. The activated membrane was cast and immersed into a sodium carbonate (Na2CO3) aqueous solution for taking the one-step NIPS-mineralization process. This proposed NIPS-mineralization mechanism comes to two conclusions: (i) the resulting membrane with comprehensive oleophobic properties and enhanced permeation flux for applications of oil/water separation with ultralow fouling and (ii) simplified the procedure to optimize the membrane performance using regular NIPS steps. The current work explores a one-step NIPS-mineralization technique that offers a novel approach to preparing membranes with highly efficient oil/water separation performance.

An antifouling electrochemical biosensor based on oxidized bacterial cellulose and quaternized chitosan for reliable detection of involucrin in wound exudate.

The monitoring of biomarkers in wound exudate is of great importance for wound care and treatment, and electrochemical biosensors with high sensitivity are potentially useful for this purpose. However, conventional electrochemical biosensors always suffer from severe biofouling when performed in the complex wound exudate. Herein, an antifouling electrochemical biosensor for the detection of involucrin in wound exudate was developed based on a wound dressing, oxidized bacterial cellulose (OxBC) and quaternized chitosan (QCS) composite hydrogel. The OxBC/QCS hydrogel was prepared using an in-situ chemical oxidation and physical blending method, and the proportion of OxBC and QCS was optimized to achieve electrical neutrality and enhanced hydrophilicity, therefore endowing the hydrogel with exceptional antifouling and antimicrobial properties. The involucrin antibody SY5 was covalently bound to the OxBC/QCS hydrogel to construct the biosensor, and it demonstrated a low limit of detection down to 0.45 pg mL-1 and a linear detection range from 1.0 pg mL-1 to 1.0 µg mL-1, and it was capable of detecting targets in wound exudate. Crucially, the unique antifouling and antimicrobial capability of the OxBC/QCS hydrogel not only extends its effective lifespan but also guarantees the sensing performance of the biosensor. The successful application of this wound dressing, OxBC/QCS hydrogel for involucrin detection in wound exudate demonstrates its promising potential in wound healing monitoring.

Interrupting marine fouling with active buffered coatings.

Biofouling on marine surfaces causes immense material and financial harm for maritime vessels and related marine industries. Previous reports have shown the effectiveness of amphiphilic coating systems based on poly(dimethylsiloxane) (PDMS) against such marine foulers. Recent studies on biofouling mechanisms have also demonstrated acidic microenvironments in biofilms and stronger adhesion at low-pH conditions. This report presents the design and utilization of amphiphilic polymer coatings with buffer functionalities as an active disruptor against four different marine foulers. Specifically, this study explores both neutral and zwitterionic buffer systems for marine coatings, offering insights into coating design. Overall, these buffer systems were found to improve foulant removal, and unexpectedly were the most effective against the diatom Navicula incerta.

Long-Term Prevention of Biofilm Formation by Polycatechol-Based Supramolecular Assemblies with Low Molecular Weight Polymers on Surfaces.

Achievement of a stable surface coating with long-term resistance to biofilm formation remains a challenge. Catechol-based polymerization chemistry and surface deposition are used as tools for surface modification of diverse materials. However, the control of surface deposition of the coating, surface coverage, coating properties, and long-term protection against biofilm formation remain to be solved. We report a new approach based on supramolecular assembly to generate long-acting antibiofilm coating. Here, we utilized catechol chemistry in combination with low molecular weight amphiphilic polymers for the generation of such coatings. Screening studies with diverse low molecular weight (LMW) polymers and different catechols are utilized to identify lead compositions, which resulted in a thick coating with high surface coverage, smoothness, and antibiofilm activity. We have identified that small supramolecular assemblies (∼10 nm) formed from a combination of polydopamine and LMW poly(N-vinyl caprolactam) (PVCL) resulted in relatively thick coating (∼300 nm) with excellent surface coverage in comparison to other polymers and catechol combinations. The coating properties, such as thickness (10-300 nm) and surface hydrophilicity (with water contact angle: 20-60°), are readily controlled. The optimal coating composition showed excellent antibiofilm properties with long-term (>28 days) antibiofilm activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains. We further utilized the combination of optimal binary coating with silver to generate a coating with sustained release of silver ions, resulting in killing both adhered and planktonic bacteria and preventing long-term surface bacterial colonization. The new coating method utilizing LMW polymers opens a new avenue for the development of a novel class of thick, long-acting antibiofilm coatings.

Effects of a dual functional filler, polyethersulfone-g-carboxymethyl chitosan@MWCNT, for enhanced antifouling and penetration performance of PES composite membranes.

Ultrafiltration technology, separating water from impurities by the core membrane, is an effective strategy for treating wastewater to meet the ever-growing requirement of clean and drinking water. However, the similar nature of hydrophobic organic pollutants and the membrane surface leads to severe adsorption and aggregation, resulting unavoidable membrane degradation of penetration and rejection. The present study presents a novel block amphiphilic polymer, polyethersulfone-g-carboxymethyl chitosan@MWCNT (PES-g-CMC@MWCNT), which is synthesized by grafting hydrophobic polyethersulfone to hydrophilic carboxymethyl chitosan in order to suspend CMC in organic solution. A mixture of hydrophilic carboxymethyl chitosan and hydrophobic polymers (polyethersulfone), in which hydrophilic segments are bonded to hydrophobic segments, could provide hydrophilic groups, as well as gather and remain stable on membrane surfaces by their hydrophobic interaction for improved compatibility and durability. The resultant ultrafiltration membranes exhibit high water flux (198.10 L m-2·h-1), suitable hydrophilicity (64.77°), enhanced antifouling property (82.96%), while still maintains excellent rejection of bovine serum albumin (91.75%). There has also been an improvement in membrane cross-sectional morphology, resulting in more regular pores size (47.64 nm) and higher porosity (84.60%). These results indicate that amphiphilic polymer may be able to significantly promote antifouling and permeability of ultrafiltration membranes.

An injectable and antifouling hydrogel prevents the development of abdominal adhesions by inhibiting the CCL2/CCR2 interaction.

Abdominal adhesion, a serious complication of abdominal surgery, often resists mitigation by current drug administration and physical barriers. To address this issue, we developed an injectable, antifouling hydrogel through the free-radical polymerization of methacrylate chondroitin sulfate (CS-GMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) monomers, dubbed the CGM hydrogel. We systematically analyzed its physicochemical properties, including rheological strength, biocompatibility, and antifouling capabilities. A rat abdominal cecum adhesion model was constructed to assess the effectiveness of CGM hydrogel in preventing postoperative adhesion and recurrent adhesion. In addition, multi-omics analyses identified the relationship between adhesion development and CCL2/CCR2 interaction. Notably, CGM hydrogel can thwart the recruitment and aggregation of fibroblasts and macrophages by inhibiting the CCL2/CCR2 interaction. Moreover, CGM hydrogel significantly dampens the activity of fibrosis-linked cytokines (TGF-ßR1) and recalibrates extracellular matrix deposition-related cytokines (t-PA and PAI-1, Col Ⅰ and MMP-9). Cumulatively, the dual action of CGM hydrogel-as a physical barrier and cytokine regulator-highlights its promising potential in clinical application for abdominal adhesion prevention.

Metal record of copper-based antifouling paints in sediment core following marina construction and operation.

Marinas are central hubs of global maritime leisure and transport, yet their operations can deteriorate the environmental quality of sediments. In response, this study investigated the metal contamination history associated with antifouling paint uses in a sediment core collected from Bracuhy marina (Southeast Brazil). Analysis target major and trace elements (Cu, Zn, Pb, Cd and Sn), rare earth elements (REEs), and Pb isotopes. The modification in Pb isotopic ratios and REEs pattern unequivocally revealed sediment provenance disruption following the marina construction. Metal distribution in the sediment core demonstrates that concentrations of Cu and Zn increased by up to 15 and 5 times, respectively, compared to the local background. This severe Cu and Zn contamination coincides with the onset of marina operations and can be attributed to the use of antifouling paints.

Lubricant-Coated Organ-on-a-Chip for Enhanced Precision in Preclinical Drug Testing.

In drug discovery, human organ-on-a-chip (organ chip) technology has emerged as an essential tool for preclinical testing, offering a realistic representation of human physiology, real-time monitoring, and disease modeling. Polydimethylsiloxane (PDMS) is commonly used in organ chip fabrication owing to its biocompatibility, flexibility, transparency, and ability to replicate features down to the nanoscale. However, the porous nature of PDMS leads to unintended absorption of small molecules, critically affecting the drug response analysis. Addressing this challenge, the precision drug testing organ chip (PreD chip) is introduced, an innovative platform engineered to minimize small molecule absorption while facilitating cell culture. This chip features a PDMS microchannel wall coated with a perfluoropolyether-based lubricant, providing slipperiness and antifouling properties. It also incorporates an ECM-coated semi-porous membrane that supports robust multicellular cultures. The PreD chip demonstrates its outstanding antifouling properties and resistance to various biological fluids, small molecule drugs, and plasma proteins. In simulating the human gut barrier, the PreD chip demonstrates highly enhanced sensitivity in tests for dexamethasone toxicity and is highly effective in assessing drug transport across the human blood-brain barrier. These findings emphasize the potential of the PreD chip in advancing organ chip-based drug testing methodologies.

Bioinspired Dopamine and N-Oxide-Based Zwitterionic Polymer Brushes for Fouling Resistance Surfaces.

Biofouling is a great challenge for engineering material in medical-, marine-, and pharmaceutical-related applications. In this study, a novel trimethylamine N-oxide (TMAO)-analog monomer, 3-(2-methylacrylamido)-N,N-dimethylpropylamine N-oxide (MADMPAO), was synthesized and applied for the grafting of poly(MADMPAO) (pMPAO) brushes on quartz crystal microbalance (QCM) chips by the combination of bio-inspired poly-dopamine (pDA) and surface-initiated atom transfer radical polymerization technology. The result of ion adsorption exhibited that a sequential pDA and pMPAO arrangement from the chip surface had different characteristics from a simple pDA layer. Ion adsorption on pMPAO-grafted chips was greatly inhibited at low salt concentrations of 1 and 10 mmol/L due to strong surface hydration in the presence of charged N+ and O- of zwitterionic pMPAO brushes on the outer layer on the chip surface, well known as the "anti-polyelectrolyte" effect. During BSA adsorption, pMPAO grafting also led to a marked decrease in frequency shift, indicating great inhibition of protein adsorption. It was attributed to weaker BSA-pMPAO interaction. In this study, the Au@pDA-4-pMPAO chip with the highest coating concentration of DA kept stable dissipation in BSA adsorption, signifying that the chip had a good antifouling property. The research provided a novel monomer for zwitterionic polymer and demonstrated the potential of pMPAO brushes in the development and modification of antifouling materials.

Design and Characterization of a Dual-Protein Strategy for an Early-Stage Assay of Ovarian Cancer Biomarker Lysophosphatidic Acid.

The overall 5-year survival rate of ovarian cancer (OC) is generally low as the disease is often diagnosed at an advanced stage of progression. To save lives, OC must be identified in its early stages when treatment is most effective. Early-stage OC causes the upregulation of lysophosphatidic acid (LPA), making the molecule a promising biomarker for early-stage detection. An LPA assay can additionally stage the disease since LPA levels increase with OC progression. This work presents two methods that demonstrate the prospective application for detecting LPA: the electromagnetic piezoelectric acoustic sensor (EMPAS) and a chemiluminescence-based iron oxide nanoparticle (IONP) approach. Both methods incorporate the protein complex gelsolin-actin, which enables testing for detection of the biomarker as the binding of LPA to the complex results in the separation of gelsolin from actin. The EMPAS was characterized with contact angle goniometry and atomic force microscopy, while gelsolin-actin-functionalized IONPs were characterized with transmission electron microscopy and Fourier transform infrared spectroscopy. In addition to characterization, LPA detection was demonstrated as a proof-of-concept in Milli-Q water, buffer, or human serum, highlighting various LPA assays that can be developed for the early-stage detection of OC.

Functionalized Surface Coatings for Rigid Contact Lenses.

This research evolves into a comparative study of three different phenolic composites as coatings for rigid contact lenses, with a particular emphasis on enhancing their antifouling properties and hydrophobicity. The primary layer, comprised of diverse phenolic compounds, serves as a sturdy foundation. An exclusive secondary layer, featuring synthetic peptoids, is introduced to further minimize biofouling. Validated through X-ray photoelectron spectroscopy, the surface analysis confirms the successful integration of the polyphenolic layers and the subsequent grafting of peptoids onto the lens surface. The efficacy of the proposed coatings is substantiated through protein adsorption tests, providing definitive evidence of their antifouling capabilities. This research employs a nuanced assessment of coating performance, utilizing the quantification of fluorescence intensity to gauge effectiveness. Additionally, contact angle measurements offer insights into wettability and surface characteristics, contributing to a comprehensive understanding of the coating's practicality.

pH-responsive membranes: Mechanisms, fabrications, and applications.

Understanding the mechanisms of pH-responsiveness allows researchers to design and fabricate membranes with specific functionalities for various applications. The pH-responsive membranes (PRMs) are particular categories of membranes that have an amazing aptitude to change their properties such as permeability, selectivity and surface charge in response to changes in pH levels. This review provides a brief introduction to mechanisms of pH-responsiveness in polymers and categorizes the applied polymers and functional groups. After that, different techniques for fabricating pH-responsive membranes such as grafting, the blending of pH-responsive polymers/microgels/nanomaterials, novel polymers and graphene-layered PRMs are discussed. The application of PRMs in different processes such as filtration membranes, reverse osmosis, drug delivery, gas separation, pervaporation and self-cleaning/antifouling properties with perspective to the challenges and future progress are reviewed. Lastly, the development and limitations of PRM fabrications and applications are compared to provide inclusive information for the advancement of next-generation PRMs with improved separation and filtration performance.

Surface Reconstruction of Silicone-Based Amphiphilic Polymers for Mitigating Marine Biofouling.

Poly(dimethylsiloxane) (PDMS) coatings are considered to be environmentally friendly antifouling coatings. However, the presence of hydrophobic surfaces can enhance the adhesion rate of proteins, bacteria and microalgae, posing a challenge for biofouling removal. In this study, hydrophilic polymer chains were synthesised from methyl methacrylate (MMA), Poly(ethylene glycol) methyl ether methacrylate (PEG-MA) and 3-(trimethoxysilyl) propyl methacrylate (TPMA). The crosslinking reaction between TPMA and PDMS results in the formation of a silicone-based amphiphilic co-network with surface reconstruction properties. The hydrophilic and hydrophobic domains are covalently bonded by condensation reactions, while the hydrophilic polymers migrate under water to induce surface reconstruction and form hydrogen bonds with water molecules to form a dense hydrated layer. This design effectively mitigates the adhesion of proteins, bacteria, algae and other marine organisms to the coating. The antifouling performance of the coatings was evaluated by assessing their adhesion rates to proteins (BSA-FITC), bacteria (B. subtilis and P. ruthenica) and algae (P. tricornutum). The results show that the amphiphilic co-network coating (e.g., P-AM-15) exhibits excellent antifouling properties against protein, bacterial and microalgal fouling. Furthermore, an overall assessment of its antifouling performance and stability was conducted in the East China Sea from 16 May to 12 September 2023, which showed that this silicon-based amphiphilic co-network coating remained intact with almost no marine organisms adhering to it. This study provides a novel approach for the development of high-performance silicone-based antifouling coatings.

In Situ Generation of Nanoparticles on and within Polymeric Materials.

It is well-established that the structural, morphological and performance characteristics of nanoscale materials critically depend upon the dispersion state of the nanofillers that is, in turn, largely determined by the preparation protocol. In this report, we review synthetic strategies that capitalise on the in situ generation of nanoparticles on and within polymeric materials, an approach that relies on the chemical transformation of suitable precursors to functional nanoparticles synchronous with the build-up of the nanohybrid systems. This approach is distinctively different compared to standard preparation methods that exploit the dispersion of preformed nanoparticles within the macromolecular host and presents advantages in terms of time and cost effectiveness, environmental friendliness and the uniformity of the resulting composites. Notably, the in situ-generated nanoparticles tend to nucleate and grow on the active sites of the macromolecular chains, showing strong adhesion on the polymeric host. So far, this strategy has been explored in fabrics and membranes comprising metallic nanoparticles (silver, gold, platinum, copper, etc.) in relation to their antimicrobial and antifouling applications, while proof-of-concept demonstrations for carbon- and silica-based nanoparticles as well as titanium oxide-, layered double hydroxide-, hectorite-, lignin- and hydroxyapatite-based nanocomposites have been reported. The nanocomposites thus prepared are ideal candidates for a broad spectrum of applications such as water purification, environmental remediation, antimicrobial treatment, mechanical reinforcement, optical devices, etc.

Antifouling activities of proteinase K and α-amylase enzymes: Laboratory bioassays and in silico analysis.

The application of enzymes as antifoulants is one of the environment-friendly strategies in biofouling management. In this study, antifouling activities of commercially available proteinase K and α-amylase enzymes were evaluated using barnacle larva and biofilm-forming bacteria as test organisms. The enzymes were also tested against barnacle cement protein through in silico analysis. The results showed that both enzymes inhibited the attachment of bacteria and settlement of barnacle larvae on the test surface. The lowest minimum inhibitory concentration of 0.312 mg ml-1 was exhibited by proteinase K against biofilm-forming bacteria. The calculated LC50 values for proteinase K and α-amylase against the barnacle nauplii were 91.8 and 230.96 mg ml-1 respectively. While α-amylase showed higher antibiofilm activity, proteinase K exhibited higher anti-larval settlement activity. Similarly, in silico analysis of the enzymes revealed promising anti-settlement activity, as the enzymes showed good binding scores with barnacle cement protein. Overall, the results suggested that the enzymes proteinase K and α-amylase could be used in antifouling coatings to reduce the settlement of biofouling on artificial materials in the marine environment.

Recent advances in emerging integrated anticorrosion and antifouling nanomaterial-based coating solutions.

The rapid progress in the marine industry has resulted in notable challenges related to biofouling and surface corrosion on underwater infrastructure. Conventional coating techniques prioritise individual protective properties, such as offering either antifouling or anticorrosion protection. Current progress and innovations in nanomaterials and technologies have presented novel prospects and possibilities in the domain of integrated multifunctional coatings. These coatings can provide simultaneous protection against fouling and corrosion. This review study focuses on the potential applications of various nanomaterials, such as carbon-based nanostructures, nano-metal oxides, polymers, metal-organic frameworks, and nanoclays, in developing integrated multifunctional nano-based coatings. These emerging integrated multifunctional coating technologies recently developed and are currently in the first phases of development. The potential opportunities and challenges of incorporating nanomaterial-based composites into multifunctional coatings and their future prospects are discussed. This review aims to improve the reader's understanding of the integrated multifunctional nano-material composite coating design and encourage valuable contributions to its development.

Novel technique for the ultra-sensitive detection of hazardous contaminants using an innovative sensor integrated with a bioreactor.

This study introduces an evaluation methodology tailored for bioreactors, with the aim of assessing the stress experienced by algae due to harmful contaminants released from antifouling (AF) paints. We present an online monitoring system equipped with an ultra-sensitive sensor that conducts non-invasive measurements of algal culture's optical density and physiological stage through chlorophyll fluorescence signals. By coupling the ultra-sensitive sensor with flash-induced chlorophyll fluorescence, we examined the dynamic fluorescence changes in the green microalga Chlamydomonas reinhardtii when exposed to biocides. Over a 24-h observation period, increasing concentrations of biocides led to a decrease in photosynthetic activity. Notably, a substantial reduction in the maximum quantum yield of primary photochemistry (FV/FM) was observed within the first hour of exposure. Subsequently, we detected a partial recovery in FV/FM; however, this recovery remained 50% lower than that of the controls. Integrating the advanced submersible sensor with fluorescence decay kinetics offered a comprehensive perspective on the dynamic alterations in algal cells under the exposure to biocides released from antifouling coatings. The analysis of fluorescence relaxation kinetics revealed a significant shortening of the fast and middle phases,  along with an increase in the duration of the slow phase, for the coating with the highest levels of biocides. Combining automated culturing and measuring methods, this approach has demonstrated its effectiveness as an ultrasensitive and non-invasive tool for monitoring the physiology of photosynthetic cultures. This is particularly valuable in the context of studying microalgae and their early responses to various environmental conditions, as well as the potential to develop an AF system with minimal harm to the environment.

Mini critical review: Membrane fouling control in membrane bioreactors by microalgae.

Membrane bioreactors (MBRs) hold significant promise for wastewater treatment, yet the persistent challenge of membrane fouling impedes their practical application. One promising solution lies in the synergy between microalgae and bacteria, offering efficient nutrient removal, reduced energy consumption, and potential mitigation of extracellular polymeric substances (EPS) concentrations. Inoculating microalgae presents a promising avenue to address membrane fouling in MBRs. This review marks the first exploration of utilizing microalgae for membrane fouling control in MBR systems. The review begins with a comprehensive overview of the evolution and distinctive traits of microalgae-MBRs. It goes further insight into the performance and underlying mechanisms facilitating the reduction of membrane fouling through microalgae intervention. Moreover, the review not only identifies the challenges inherent in employing microalgae for membrane fouling control in MBRs but also illuminates prospective pathways for future advancement in this burgeoning field.