Impact of Antifouling PEG Layer on the Performance of Functional Peptides in Regulating Cell Behaviors

Engineered Antifouling Peptides with Sarcosine Branches for Robust Electrochemical Detection of the HER2 Biomarker in Real Biological Samples

In complex biological matrices, the nonspecific adsorption phenomena occurring on the surfaces of electrochemical biosensors represent a considerable challenge for the precise detection of targets in heterogeneous biological samples. Furthermore, the presence of protein hydrolases in biofluids also affects the stability of biosensing devices utilizing natural proteins or peptides. It is therefore imperative to develop sensing devices capable of effectively minimizing such effects in real biological samples. Herein, we engineered a sarcosine branch-chain peptide (SBCP) with a strong antifouling capability to avoid biofouling and enhanced stability to resist hydrolysis by proteases. The peptide is composed of three sections: an anchoring sequence (CPPPP), an antifouling sequence (EK(Sar)EK(Sar)EK(Sar)EK(Sar)), and a recognition sequence (HLTVSPWY). An electrochemical biosensor was developed through the electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) incorporated with poly(norepinephrine) (PNE) on an electrode surface, followed by the electrodeposition of gold nanoparticles and the self-assembly of SBCP. The biosensor constructed using the SBCP containing a specific recognizing peptide sequence for the cancer biomarker human epidermal growth factor receptor 2 (HER2) was capable of sensitively detecting target HER2, within the concentration range of 1.0 pg mL-1 to 1.0 μg mL-1 and with a limit of detection of 0.37 pg mL-1. Moreover, the biosensor demonstrated antifouling ability and the capacity to accurately detect the target in human serum, exhibiting a high degree of concordance with the assaying results of ELISA kits. These findings suggest that the biosensor based on the engineered peptides possesses promising potential for practical applications.

A Robust Biosensor Based on Dual Loop Constrained Antifouling Peptide for Electrochemical Detection of Human Insulin like Growth Factor 1 in Blood

Human insulin-like growth factor 1 (IGF-1) levels in human blood serve as a reliable biomarker for assessing endogenous growth hormone secretion and are also implicated in the pathogenesis of various cancers, highlighting their broad clinical diagnostic value. However, the direct detection of IGF-1 in complex blood samples with electrochemical biosensors is challenging due to the severe biofouling and the enzymes in the blood that may cause degradation of biomolecules functionalized on the sensor surfaces. Herein, a dual-loop constrained antifouling peptide (DLC-AP) was designed and constructed through the covalent cyclization of linear antifouling peptides, and it was further used for the development of an antifouling electrochemical biosensor. The DLC-AP exhibited exceptional antifouling properties in complex biological media, and its structural stability against enzymatic degradation by proteolytic enzymes in blood significantly enhanced the stability and antifouling performance of the biosensor. The DLC-AP-based biosensor demonstrated high sensitivity for IGF-1 detection in human blood samples, achieving a linear response range of 0.1 pM to 100.0 nM with a low limit of detection (7.0 fM), and its assay results of IGF-1 levels in clinical blood samples showed agreement with the ELISA results. This strategy of peptide and biosensor design offers a promising avenue for the construction of antifouling biosensing devices for biomarker monitoring in complex human blood.

Tailoring Protein Adsorption at the Solid-Liquid Interface for Long-Term Superhemophobicity

Super-repellent surfaces with micro/nanoscale roughness can sustain blood in the Cassie-Baxter state and minimize the solid-liquid contact area, exhibiting potential for biomedical applications. Conventional superhydrophobic surfaces with hydrophobic solid-liquid interface are susceptible to protein adsorption under blood flow, leading to a transition to the Wenzel state and increasing the risk of thrombosis. Inspired by Salvinia, hydrophilic molecules are incorporated at the solid-liquid contact area based on the interaction between blood and the surface topography as well as chemistry, thereby engineering a chemically heterogeneous superhemophobic surface which effectively prevents protein adsorption and maintains a long-term Cassie-Baxter state. The blood-repellent time of the heterogeneous surface is greater than tenfold those of conventional superhydrophobic surfaces. In vivo rabbit blood circulation confirms sustained hemocompatibility and effective thrombosis resistance, demonstrating prolonged superhemophobicity for over 55 h. The heterogeneous design ensures extended resistance to complex biological fluids and is promising for the development of blood-contacting devices, such as the gas-permeable blood-repellent membranes for extracorporeal membrane oxygenators.

Fabrication of cost-effective antifouling sensors with conjugation of hyaluronic acid and phase-transited BSA for the rapid detection of gentamicin

Matrix interference poses persistent and significant challenges against rapidly detecting gentamicin residue in foods. Here, we fabricated synergistic antifouling surfaces using the phase transition of bovine serum albumin (PTB) and hyaluronic acid (HA) on substrates. The hybrid PTB + HA coatings showed ultralow adsorption of BSA and lysozyme, requiring 10 times less PTB dosage. With PTB's assistance, the modification of HA proved to be much more cost-effective than the sulfhydrated HA. The adsorption of E. coli on the hybrid coatings could be reduced by 92.6 %, illustrating good properties of antibacterial adsorption. Furthermore, the hybrid surfaces demonstrated good stability despite being rinsed with strong acid and alkaline solutions. Based on the immune-inhibition assay, the sensitive antifouling sensors were developed with a low detection limit (1.8 ng/mL for gentamicin) and satisfactory recovery rate (94.0 %-104.0 %) in goat milk. All tests could be completed within 10 min, confirming the sensor system's feasibility and efficiency.

Tyramide signal amplification for a highly sensitive multiplex immunoassay based on encoded hydrogel microparticles

Proteins play a crucial role as mediators of immune regulation, homeostasis, and metabolism, making their quantification essential for understanding disease mechanisms in biomedical research and clinical diagnostics. However, conventional methods when used to detect proteins in clinical samples exhibit difficulty in terms of sensitivity, dynamic range, and multiplex capacity. In this study, we developed a highly sensitive multiplex immunoassay based on encoded hydrogel microparticles (MPs) utilizing tyramide signal amplification (TSA). The combination of the large multiplexing capacity of encoded hydrogel microparticles and the signal amplification of tyramide enables a highly sensitive multiplex immunoassay. By employing TSA, we are able to achieve larger detection signals with higher specificity. We effectively decreased the non-specific binding in the hydrogel network by blocking the unreacted acrylate double bonds remaining after the capture antibody-conjugation step and acquired a 3-fold increase in the signal-to-noise ratio. Also, we optimized three parameters mainly affecting the assay sensitivity: the detection antibody concentration, the biotinyl tyramide concentration, and the TSA reaction time. This approach leads to a significant improvement in assay sensitivity, achieving a limit of detection as low as 58 fg mL-1. Compared to the previous method, the assay sensitivity is enhanced 10-fold. In addition, the multiplex capability of the assay is validated by detecting cytokines IL-4, IL-5, IL-6, IL-9, and IL-17, with no observed cross-reactivity. Finally, with enhanced sensitivity, we demonstrate the clinical applicability of our platform by successfully multiplexing these cytokines at concentrations down to several hundreds of fg mL-1 within human serum, which could not be detected using previous methods.

Direct Measurements of Overlooked Long-Range Interactions near Zwitterionic and Nonionic Polymer Brushes

Current research on the antifouling mechanisms of "electrically neutral" polymer brushes predominantly emphasizes thermodynamically unfavorable short-range interactions. However, our study reveals the critical importance of long-range interactions. By utilizing zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and nonionic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) brushes as model systems, we employed total internal reflection microscopy (TIRM) to directly measure interactions with contaminants. Surprisingly, even seemingly neutral polymers exhibit significant electrostatic interactions with nearby contaminants─a fact that has been largely overlooked in this field. Our findings challenge the prevailing assumption of charge absence on surfaces grafted with antifouling polymer brushes and investigate how external stimuli (such as ionic strength and polymer conformation) affect these long-range interactions. In conclusion, this study presents a novel approach to exploring long-range interactions near polymer-grafted surfaces, offering valuable insights for the development of antifouling materials and biomedical applications in the future.

Small-Molecule Self-Assembly Strategy for Ultrafast, Sensitive, and Portable Multiplexed Antibiotics Detection by Transistor Biosensor Arrays

The urgent need for portable, sensitive, and accurate techniques to analyze multiple antibiotics is critical to mitigating the health risks associated with low-dose antibiotics coexposure-induced drug resistance, especially in infants. Emerging field-effect transistor (FET) biosensors are expected to realize the above requirement, but face challenges in terms of sensitivity and selectivity for complex solutions in practical applications. Here, we introduce a small-molecule coating strategy on carbon nanotube (CNT)-FET biosensor arrays to simultaneously block nonspecific adsorption and minimize Debye shielding effects, coupled with aptamer for antibiotics recognition through inkjet printing technology, which significantly improves the selectivity and sensitivity. The developed portable detection system with the FET biosensor chip displayed an ultrafast response time of 100 s, high sensitivity at the femtomolar level for both simultaneous detection and quantification of multiple antibiotics (kanamycin, oxytetracycline, and sulfaquinoxaline), a wide linear range from femtomolar to nanomolar concentrations, and exceptional accuracy, with a recovery rate of 91.1 to 107.5%. This work presents a biosensor array that can quantify various antibiotics at extremely low concentrations in milk samples, is superior to the enzyme-linked immunosorbent assay (ELISA) method, and can also be applied for the detection of other biomarkers, such as toxins and hormones.

Regulating Cell-Material Interfacial Interactions through Selective Cellular Resistance

Regulating the behavior of different types of cells at the material-tissue interface is pivotal for inducing tissue regeneration. Traditional methods enhance target cell activity using specific ligands such as peptides and antibodies, which have stability issues within biological environments. Herein, we show that selective cell resistance can be realized by fine-tuning the material surface chemistry, achieving strong cell selectivity superior to that of extracellular matrix peptides. A certain degree of adsorption resistance differentially affects the adhesion of various types of cells on material surfaces. Taking this principle into account, a polyethylene glycol (PEG) grafted surface was meticulously fine-tuned to selectively support endothelial cells (ECs) while resisting smooth muscle cell attachment. Mechanistic studies identified that the difference in myosin II expression is crucial for cell selectivity. An EC-selective polymer coating for cardiovascular devices was fabricated to promote rapid surface endothelialization and prevent neointimal hyperplasia in vivo.

Antifouling Polymer Coatings for Bioactive Surfaces

Bioactive surfaces play a pivotal role in biomedical applications by enabling precise biological interactions through immobilized functional molecules. However, their performance is often hindered by nonspecific protein adsorption and cell adhesion. Antifouling polymer coatings have emerged as an effective solution, creating hydration barriers to preserve functionality and reduce biofouling. This review provides an overview of the recent advances in the development of antifouling polymer coatings for bioactive surfaces, with particular focus on nonionic polymers, such as polyethylene glycol (PEG), and zwitterionic polymers like poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC). Among them, zwitterionic polymers, with their unique charge-balanced structures, exhibit exceptional hydration, protein resistance, and stability, making them particularly promising for biomedical applications. In addition, key applications of these bioactive surfaces, including their use in anticoagulant materials, antibacterial coatings, and biosensor interfaces, are also discussed. The discussion concludes with an address of the field's challenges and future directions, highlighting the need for innovative materials that balance antifouling properties, biocompatibility, and long-term stability for both clinical and industrial use. This review aims to review the latest advancements in antifouling polymer coatings for bioactive surfaces and provide insights into optimizing multifunctional bioactive surfaces to meet the evolving and dynamic demands of the biomedical field.

Bioinspired Materials for Controlling Mineral Adhesion: From Innovation Design to Diverse Applications

The advancement of controllable mineral adhesion materials has significantly impacted various sectors, including industrial production, energy utilization, biomedicine, construction engineering, food safety, and environmental management. Natural biological materials exhibit distinctive and controllable adhesion properties that inspire the design of artificial systems for controlling mineral adhesion. In recent decades, researchers have sought to create bioinspired materials that effectively regulate mineral adhesion, significantly accelerating the development of functional materials across various emerging fields. Herein, we review recent advances in bioinspired materials for controlling mineral adhesion, including bioinspired mineralized materials and bioinspired antiscaling materials. First, a systematic overview of biological materials that exhibit controllable mineral adhesion in nature is provided. Then, the mechanism of mineral adhesion and the latest adhesion characterization between minerals and material surfaces are introduced. Later, the latest advances in bioinspired materials designed for controlling mineral adhesion are presented, ranging from the molecular level to micro/nanostructures, including bioinspired mineralized materials and bioinspired antiscaling materials. Additionally, recent applications of these bioinspired materials in emerging fields are discussed, such as industrial production, energy utilization, biomedicine, construction engineering, and environmental management, highlighting their roles in promoting or inhibiting aspects. Finally, we summarize the ongoing challenges and offer a perspective on the future of this charming field.

Coacervate-Derived Assembly of Poly(ethylene glycol) Nanoparticles for Combinational Tumor Therapy

Coacervates have garnered significant attention as potential drug carriers. However, the instability resulting from their intrinsic membrane-free nature restricts the application of coacervates in drug delivery. Herein, the engineering of poly(ethylene glycol) nanoparticles (PEG NPs) is reported using coacervates composed of PEG and polyphenols as the templates, where PEG is subsequently cross-linked based on different chemistries (e.g., thiol-disulfide exchange, click chemistry, and Schiff base reaction). The reported assembly strategy avoids the template removal process and the resultant PEG NPs exhibit excellent stability in the physiological environment compared to coacervates. The presence of polyphenols in PEG NPs enables the loading of various cargos including metal ions (i.e., Ru, Gd, Mn, Fe) and drug molecules (i.e., doxorubicin), which demonstrates their promise in magnetic resonance imaging and combinational tumor therapy. This work provides a promising strategy to promote the development of coacervate-derived NPs as a drug delivery system for biomedical applications.

Tough Polyurethane Hydrogels with a Multiple Hydrogen-Bond Interlocked Bicontinuous Phase Structure Prepared by In Situ Water-Induced Microphase Separation

Hydrogels with mechanical performances similar to load-bearing tissues are in demand for in vivo applications. In this work, inspired by the self-assembly behavior of amphiphilic polymers, polyurethane-based tough hydrogels with a multiple hydrogen-bond interlocked bicontinuous phase structure through in situ water-induced microphase separation strategy are developed, in which poly(ethylene glycol)-based polyurethane (PEG-PU, hydrophilic) and poly(ε-caprolactone)-based polyurethane (PCL-PU, hydrophobic) are blended to form dry films followed by water swelling. A multiple hydrogen bonding factor, imidazolidinyl urea, is introduced into the synthesis of the two polyurethanes, and the formation of multiple hydrogen bonds between PEG-PU and PCL-PU can promote homogeneous microphase separation for the construction of bicontinuous phase structures in the hydrogel network, by which the hydrogel features break strength of 12.9 MPa, fracture energy of 2435 J m-2, and toughness of 48.2 MJ m-3. As a biomedical patch, the outstanding mechanical performances can withstand abdominal pressure to prevent hernia formation in the abdominal wall defect model. Compared to the commercial PP mesh, hydrogel can prevent tissue/organ adhesion to reduce inflammatory responses and promote angiogenesis, thereby accelerating the repair of abdominal wall defects. This work may provide useful inspiration for researchers to design different gel materials through solvent-induced microphase separation.

Antifouling Hydrogel Based on Zwitterionic Poly(carboxybetaine diacrylate) Cross-Linkers

Antifouling zwitterionic materials have extensive applications in the biomedical field. This study designed and successfully synthesized a novel poly(carboxybetaine) diacrylate (PCBDA) via cationic ring-opening polymerization of 2-methyl-2-oxazine, chain modification by the Michael reaction, and chain end transformation to acrylate. The cross-linker was obtained with a tunable molecular weight. Through photopolymerization, poly(carboxybetaine) (PCB) hydrogels with varying solid contents were obtained, and the effects of the solid content on the hydration properties, mechanical properties, and microstructure of the PCB hydrogels were investigated. Furthermore, the non-fouling properties of the PCB hydrogels were compared to those of commercial polyethylene glycol (PEG) hydrogels. Protein adsorption on PCB hydrogels was reduced by more than 60% compared to low-fouling PEG hydrogels. PCB hydrogels exhibit antibacterial adhesion properties similar to those of PEG hydrogels. In cell adhesion experiments, no cell adhesion was observed on the PCB hydrogels, indicating their superior anti-cell adhesion function. This advancement offers a more promising alternative to polyethylene glycol diacrylate (PEGDA) cross-linkers in the design of hydrogels.

Effect of Glycosylation on the Enzymatic Degradation of D-Amino Acid-Containing Peptides

The accumulation of D-amino acid-containing peptides is associated with age-related diseases such as Alzheimer's disease and cataracts, while glycosylation is an important modification of proteins and plays a key role in improving the physicochemical properties of peptides and facilitating their regulation in biological systems. This study investigates the effects of glycosylation position, glycan number, and monosaccharide structure on the conformation and enzymatic degradation of D-amino acid-containing peptides, using KYNEtWRSED (5-t) as a model peptide and six monosaccharides as model glycans. The results demonstrated that glycosylation inhibited the enzymatic degradation of 5-t in the presence of most serine-like proteases. However, in the presence of chymotrypsin, glycosylation with modified monosaccharides (except for β-D-GalNAc) promoted the degradation of 5-t. Furthermore, glycosylation had no effect on the cleavage site of 5-t. Molecular docking analysis revealed that the hydrogen bonding and electrostatic interactions between the glycopeptide and chymotrypsin were markedly strengthened, likely serving as a key determinant of the enzymatic effects. Collectively, these findings highlight the potential of glycosylation to enhance the therapeutic and biomedical applications of D-amino acid-containing peptides in disease treatment and drug design.

Biofilm morphology and antibiotic susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) on poly-D,L-lactide-co-poly(ethylene glycol) (PDLLA-PEG) coated titanium

Biodegradable polymeric coatings are being explored as a preventive strategy for orthopaedic device-related infection. In this study, titanium surfaces (Ti) were coated with poly-D,L-lactide (PDLLA, (P)), polyethylene-glycol poly-D,L-lactide (PEGylated-PDLLA, (PP20)), or multi-layered PEGylated-PDLLA (M), with or without 1 % silver sulfadiazine. The aim was to evaluate their cytocompatibility, resistance to Staphylococcus aureus biofilm formation, and their potential to enhance the susceptibility of any biofilm formed to antibiotics. Using automated high-content screening confocal microscopy, biofilm formation of a clinical methicillin-resistant Staphylococcus aureus (MRSA) isolate expressing GFP was quantified, along with isogenic mutants that were unable to form polysaccharidic or proteinaceous biofilm matrices. The results showed that PEGylated-PDLLA coatings exhibited significant antibiofilm properties, with M showing the highest effect. This inhibitory effect was stronger in S. aureus biofilms with a matrix composed of proteins compared to those with an exopolysaccharide (PIA) biofilm matrix. Our data suggest that the antibiofilm effect may have been due to (i) inhibition of the initial attachment through microbial surface components recognising adhesive matrix molecules (MSCRAMMs), since PEG reduces protein surface adsorption via surface hydration layer and steric repulsion; and (ii) mechanical disaggregation and dispersal of microcolonies due to the bioresorbable/degradable nature of the polymers, which undergo hydration and hydrolysis over time. The disruption of biofilm morphology by the PDLLA-PEG co-polymers increased S. aureus susceptibility to antibiotics like rifampicin and fusidic acid. Adding 1 % AgSD provided additional early bactericidal effects on both biofilm and planktonic S. aureus. Additionally, the coatings were cytocompatible with immune cells, indicating their potential to enhance bacterial clearance and reduce bacterial colonisation of titanium-based orthopaedic biomaterials.

Highly precise strategy of polygalacturonic acid microcarriers functionalized with zwitterions and specific peptides for MSC screening

Microcarriers for large-scale cell culture have a broader prospect in cell screening compared with the traditional high cost, low efficiency, and cell damaging methods. However, the equal biological affinity to cells has hindered its application. Therefore, based on the antifouling strategy of zwitterionic polymer, we developed a cell-specific microcarrier (CSMC) for shielding non-target cells and capturing mesenchymal stem cells (MSCs), which has characteristics of high biocompatibility, low background noise and high precision. Briefly, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide and glycidyl methacrylate were grafted onto polygalacturonic acid, respectively. The former built a hydration layer through solvation to provide an excellent antifouling surface, while the latter provided active sites for the click reaction with sulfhydryl-modified cell-specific peptides, resulting in rapid immobilization of peptides. This method is applicable to the vast majority of polysaccharide materials. The accurate capture ratio of MSCs by CSMC in a mixed multicellular environment is >95 % and the proliferation rate of MSCs on microcarriers is satisfactory. In summary, this grafting strategy of bioactive components lays a foundation for the application of polysaccharide materials in the biomedical field, and the specific adhesive microcarriers also open up new ideas for the development of stem cell screening as well.

Generating Immunological Memory Against Cancer by Camouflaging Gold-Based Photothermal Nanoparticles in NIR-II Biowindow for Mimicking T-Cells

Photothermal therapy (PTT) against cancer not only directly ablates tumors but also induces tumor immunogenic cell death (ICD). However, the antitumor immune response elicited by ICD is insufficient to prevent relapse and metastasis because of the immunosuppressive tumor microenvironment (TME). A biomimetic nanoplatform (bmNP) mimicking cytotoxic lymphocytes (CTLs) for combinational photothermal-immunotherapy to effectively regulate the immunosuppressive TME is reported here. The bmNP is constructed by wrapping the T-cell membrane onto a new type of photothermal agents, spherical Au-based PNCs (sAuPNCs). Similar to T-cells, the bmNP enhanced accumulation at the tumor site by targeting the tumor via adhesion proteins on T-cell membrane. The obtained sAuPNCs have a wide absorption band in the second near-infrared (NIR-II) region with a high photothermal conversion efficiency (PCE) up to about 75% and excellent photostability. The bmNP with a smaller size is more superior compete with T-cells to bond with tumor cells via PD-1/PD-L1 interaction to effectively block the PD-1 checkpoint of T-cells for preventing T-cell exhaustion. Furthermore, in vivo studies reveal the immunological memory effect is significantly elicited in mice received bmNPs therapy. Collectively, bmNPs show great potential in photothermal-enhanced immunotherapy.

Guardians of Future Food Safety: Innovative Applications and Advancements in Anti-biofouling Materials

Biofilm formation is a widespread natural phenomenon that poses a substantial threat to food microbiological safety, with direct implications for consumer health. To combat this challenge effectively, one promising strategy involves the development of functional anti-biofouling layers on food-contact surfaces to deter microbial adhesion. Herein, we explore the methodologies for fabricating both hydrophilic and hydrophobic anti-biofouling materials, along with a detailed examination of their inherent antiadhesive mechanisms. Furthermore, we provide concise insights into exemplary applications of anti-biofouling materials within the context of the food industry. This comprehensive analysis not only advances our understanding of biofilm prevention but also sets the stage for innovative developments in anti-biofouling materials and their future applications in food science. These advancements hold the potential to significantly enhance food microbiological safety, ensuring that consumers can confidently enjoy food products of the highest standards in terms of hygiene and quality.

Imaging Diffusion and Stability of Single-Chain Polymeric Nanoparticles in a Multi-Gel Tumor-on-a-Chip Microfluidic Device

The performance of single-chain polymeric nanoparticles (SCPNs) in biomedical applications highly depends on their conformational stability in cellular environments. Until now, such stability studies are limited to 2D cell culture models, which do not recapitulate the 3D tumor microenvironment well. Here, a microfluidic tumor-on-a-chip model is introduced that recreates the tumor milieu and allows in-depth insights into the diffusion, cellular uptake, and stability of SCPNs. The chip contains Matrigel/collagen-hyaluronic acid as extracellular matrix (ECM) models and is seeded with cancer cell MCF7 spheroids. With this 3D platform, it is assessed how the polymer's microstructure affects the SCPN's behavior when crossing the ECM, and evaluates SCPN internalization in 3D cancer cells. A library of SCPNs varying in microstructure is prepared. All SCPNs show efficient ECM penetration but their cellular uptake/stability behavior depends on the microstructure. Glucose-based nanoparticles display the highest spheroid uptake, followed by charged nanoparticles. Charged nanoparticles possess an open conformation while nanoparticles stabilized by internal hydrogen bonding retain a folded structure inside the tumor spheroids. The 3D microfluidic tumor-on-a-chip platform is an efficient tool to elucidate the interplay between polymer microstructure and SCPN's stability, a key factor for the rational design of nanoparticles for targeted biological applications.

Emerging strategies for treating medical device and wound-associated biofilm infections

Bacterial infections represent a significant global threat to human health, leading to considerable economic losses through increased healthcare costs and reduced productivity. One major challenge in treating these infections is the presence of biofilms - structured bacterial communities that form protective barriers, making traditional treatments less effective. Additionally, the rise of antibiotic-resistant bacteria has exacerbated treatment difficulties. To address these challenges, researchers are developing and exploring innovative approaches to combat biofilm-related infections. This mini-review highlights recent advancements in the following key areas: surface anti-adhesion technologies, electricity, photo/acoustic-active materials, endogenous mimicking agents, and innovative drug delivery systems. These strategies aim to prevent biofilm formation, disrupt existing biofilms, and enhance the efficacy of antimicrobial treatments. Currently, these approaches show great potential for applications in medical fields such as medical device and wound - associated biofilm infections. By summarizing these developments, this mini-review provides a comprehensive resource for researchers seeking to advance the management and treatment of biofilm-associated infections.

The Importance of Effective Ligand Concentration to Direct Epithelial Cell Polarity in Dynamic Hydrogels

Epithelial cysts and organoids are multicellular hollow structures formed by correctly polarized epithelial cells. Important in steering these cysts from single cells is the dynamic regulation of extracellular matrix presented ligands, and matrix dynamics. Here, control over the effective ligand concentration is introduced, decoupled from bulk and local mechanical properties, in synthetic dynamic supramolecular hydrogels formed through noncovalent crosslinking of supramolecular fibers. Control over the effective ligand concentration is realized by 1) keeping the ligand concentration constant, but changing the concentration of nonfunctionalized molecules or by 2) varying the ligand concentration, while keeping the concentration of non-functionalized molecules constant. The results show that in 2D, the effective ligand concentration within the supramolecular fibers rather than gel stiffness (from 0.1 to 8 kPa) regulates epithelial polarity. In 3D, increasing the effective ligand concentration from 0.5 × 10-3 to 2 × 10-3 m strengthens the effect of increased gel stiffness from 0.1 to 2 kPa, to synergistically yield more correctly polarized cysts. Through integrin manipulation, it is shown that epithelial polarity is regulated by tension-based homeostasis between cells and matrix. The results reveal the effective ligand concentration as influential factor in regulating epithelial polarity and provide insights on engineering of synthetic biomaterials for cell and organoid culture.

Intelligent Supramolecular Modification for Implants: Endogenous Regulation of Bone Defect Repair in Osteoporosis

Addressing osteoporosis-related bone defects, a supramolecular strategy is innovated for modifying carbon fiber reinforced polyether ether ketone (CF/PEEK) composites. By covalently attaching intelligent macromolecules via in situ RAFT polymerization, leveraging the unique pathological microenvironment in patients with iron-overloaded osteoporosis, intelligent supramolecular modified implant surface possesses multiple endogenous modulation capabilities. After implantation, surface brush-like macromolecules initially resist macrophage adhesion, thereby reducing the level of immune inflammation. Over time, the molecular chains undergo conformational changes due to Fe (III) mediated supramolecular self-assembly, transforming into mechanistic signals. These signals are then specifically transmitted to pre-osteoblast cell through the binding capacity of the KRSR short peptide at the molecular terminus, induced their osteogenic differentiation via the YAP/β-catenin signaling axis. Furthermore, osteoblasts secrete alkaline phosphatase (ALP), which significantly hydrolyzes phosphate ester bonds in surface macromolecular side groups, resulting in the release of alendronate (ALN). This process further improves the local osteoporotic microenvironment. This intelligent surface modification tailors bone repair to individual conditions, automatically realize multiple endogenous regulation once implanted, and truly realize spontaneous activation of a series of responses conducive to bone repair in vivo. It is evidenced by improved bone regeneration in iron-overloaded osteoporotic rabbits and supported by in vitro validations.

DNA Nanoparticle Based 2D Biointerface to Study the Effect of Dynamic RGD Presentation on Stem Cell Adhesion and Migration

The native extracellular matrix (ECM) undergoes constant remodeling, where adhesive ligand presentation changes over time and in space to control stem cell function. As such, it is of interest to develop 2D biointerfaces able to study these complex ligand stem-cell interactions. In this study, a novel dynamic bio interface based on DNA hybridization is developed, which can be employed to control ligand display kinetics and used to study dynamic cell-ligand interaction. In this approach, mesoporous silica nanoparticles (MSN) are functionalized with single-strand DNA (MSN-ssDNA) and spin-coated on a glass substrate to create the 2D bio interface. Cell adhesive tripeptide RGD is conjugated to complementary DNA strands (csDNA) of 9, 11, or 20 nucleotides in length, to form csDNA-RGD. The resulting 3 csDNA-RGD conjugates can hybridize with the ssDNA on the MSN surface, presenting RGD with increased ligand dissociation rates as DNA length is shortened. Slow RGD dissociation rates led to enhanced stem cell adhesion and spreading, resulting in elongated cell morphology. Cells on surfaces with slow RGD dissociation rates also exhibited higher motility, migrating in multiple directions compared to cells on surfaces with fast RGD dissociation rates. This study contributes to the existing body of knowledge on dynamic ligand-stem cell interactions.

Synergistic Effect of Polyethylene Glycol and Lactic Acid on Handling Properties and Antibacterial Efficacy of Premixed Calcium Silicate Cement

Calcium silicate (CaSi) bone cement with antibacterial and osteogenic properties has attracted significant interest. However, there is a need to develop a variety of new premixed bone cement to meet the clinical requirements of fast setting time, ease of handling, and efficient antibacterial properties. In this study, different volume ratios of polyethylene glycol (PEG) and lactic acid liquids were added to calcium silicate, and the effects of varying liquid-to-powder ratios (L/P) were examined. This study assessed the physicochemical properties, cytotoxicity, and antibacterial activity against S. aureus and E. coli of this premixed cement. The results from the experiments indicated that lactic acid significantly reduced the setting time of the CaSi-based cement and enhanced its mechanical strength. Furthermore, the appropriate concentration of lactic acid and matching L/P ratio improved its washout resistance. The cell viability of all premixed cement was found to be over 80%. The premixed cement containing PEG and lactic acid exhibited superior antibacterial properties compared to the CaSi control. Based on its setting time, washout resistance, and antibacterial activity, a premixed cement with a liquid phase of 80% PEG and 20% lactic acid at an L/P ratio of 0.4 appeared promising for use in dental and orthopedic practice.

High-Performance Polyurea Improved by Reactive Nanocluster for Antibiofouling

Polyurea has found applications in protective coatings. Yet, the too fast polymerization and lack of functions limit its application. Herein, we report a high-performance polyurea via the stepwise polymerization of an isocyanate (NCO)-terminated prepolymer consisting of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (PPG-b-PEG-b-PPG) with a nanocluster synthesized via the hydrolysis of N-phenylaminomethyltriethoxysilane. Such a nanocluster contains low-reactivity secondary amines, so the polymerization of polyurea can be slowed down (over 1 h), which improves its wetting and adhesion to a substrate. The residual silanol groups on the nanocluster further increase the adhesion. Such polyurea exhibits high adhesion on various substrates, including glass, ceramic, steel, copper, titanium, wood, and natural rubber (∼2.35-14.64 MPa). Besides, the nanoclusters can cross-link the prepolymer into a tough network, endowing the polyurea with a high mechanical strength of ∼25 MPa, much higher than the traditional polyaspartic ester polyurea. On the other hand, the PEG segments enable the polyurea to have good fouling resistance against proteins (fibrinogen absorption was reduced by over 90%), bacteria (RBA of S. aureusE. coli and Pseudomonas sp. was less than 10%), as well as diatom (diatom density was less than 100 cells/mm2). The polyurea is expected to find applications in biomedical engineering and marine antifouling.

Mussel-Inspired Antimicrobial and Antifouling Coating Constructed by the Combination of Zwitterionic Copolymers and Silver Nanoparticles

Biofouling and bacterial infections are significant challenges in biomedical devices. In this study, a biocompatible dual-functional coating with antimicrobial and antifouling properties is developed by co-depositing the zwitterionic copolymer and silver nanoparticles via a dopamine-assisted strategy. Inspired by mussel adhesion, the coating exhibits substrate-independent adhesion as a result of the formation of irreversible covalent bonds. The zwitterionic copolymer in the dual coating plays a crucial role in improving surface wettability and reducing protein adsorption and platelet and bacterial adhesion, thereby improving its antifouling property significantly. The silver nanoparticles reduced by self-polymerized polydopamine without the addition of any chemical reductants can effectively improve the antimicrobial activity. Furthermore, as the zwitterion content in the zwitterion polymer increases, the antibacterial and antifouling properties of the coating can be further advanced. The simple and effective approach presented here provides a promising pathway for constructing potent antibacterial and antifouling surfaces, demonstrating great potential for clinical applications in implanted materials.

Highly efficient GPCR immobilization with enhanced fouling resistance, salt tolerance, and chromatographic performance

The feasibility of immobilized protein-based biodetection relies critically on the activity of the immobilized proteins as well as the biocompatibility of the protein surface. Although many protein immobilization strategies have been developed with satisfied detection readout signals. Non-specific interactions caused by the protein-coating surface are still of great concern since they often interfere with or affect the reliability of detection. Herein, we developed a highly efficient G protein-coupled receptor (GPCR) immobilization method by the combination of polyethylene glycol (PEG) with a self-labeling enzyme-catalyzed reaction. The immobilization relies on the covalent interaction between the fusion tag of a target GPCR (kinase domain of epidermal growth factor receptor, EGFR) and its covalent inhibitor ibrutinib, which is modified on PEGylated silica gels. Two types of GPCRs, N-methyl-D-aspartate 2 A receptor (NMDAR2A) and endothelin A receptor (ETAR), were used as examples to realize protein immobilization. The GPCR modified gels and the affinity columns packed with them have been extensively characterized, in terms of non-specific adsorptions, retention factor (k'), half peak width (W1/2), tailing factor (Tf), theoretical plates (N), and association and dissociation constants of the ligands with the receptors. The immobilized GPCRs with reduced non-specific interactions and enhanced fouling resistance, salt tolerance, and chromatographic performance were clearly observed. We believe it is the first work to introduce PEGylation in GPCR immobilization and provide comprehensive proof-of-concept studies to illustrate the improved antifouling property, salt tolerance, and chromatographic performance. This method could be generally applicable in other immobilized protein-based technology for reliable biodetection.

Optimized Design of Hyaluronic Acid-Lipid Conjugate Biomaterial for Augmenting CD44 Recognition of Surface-Engineered NK Cells

Triple-negative breast cancer (TNBC) presents treatment challenges due to a lack of detectable surface receptors. Natural killer (NK) cell-based adaptive immunotherapy is a promising treatment because of the characteristic anticancer effects of killing malignant cells directly by secreting cytokines and lytic granules. To maximize the cancer recognition ability of NK cells, biomaterial-mediated ex vivo cell surface engineering has been developed for sufficient cell membrane immobilization of tumor-targeting ligands via hydrophobic anchoring. In this study, we optimized amphiphilic balances of NK cell coating materials composed of CD44-targeting hyaluronic acid (HA)-poly(ethylene glycol) (PEG)-lipid to improve TNBC recognition and the anticancer effect. Changes in the modular design of our material by differentiating hydrophilic PEG length and incorporating lipid amount into HA backbones precisely regulated the amphiphilic nature of HA-PEG-lipid conjugates. The optimized biomaterial demonstrated improved anchoring into NK cell membranes and facilitating the surface presentation level of HA onto NK cell surfaces. This led to enhanced cancer targeting via increasing the formation of immune synapse, thereby augmenting the anticancer capability of NK cells specifically toward CD44-positive TNBC cells. Our approach addresses targeting ability of NK cell to solid tumors with a deficiency of surface tumor-specific antigens while offering a valuable material design strategy using amphiphilic balance in immune cell surface engineering techniques.

Passivation protein-adhesion platform promoting stent reendothelialization using two-electron-assisted oxidation of polyphenols

Superhydrophilic surfaces play an important role in nature. Inspired by this, scientists have designed various superhydrophilic materials that are widely used in the field of biomaterials, such as PEG molecular brushes and zwitterionic materials. However, superhydrophilic coatings with only anti-fouling properties do not satisfy the requirements for rapid reendothelialization of cardiovascular stent surfaces. Herein, a novel polyphenol superhydrophilic surface with passivated protein-adsorption properties was developed using two-electron oxidation of dopamine and polyphenols. This coating has a multiscale effects: 1) macroscopically: anti-fouling properties of superhydrophilic; 2) microscopically: protein adhesion properties of active groups (quinone-, amino-, hydroxyphenyl groups and aromatic ring). Polyphenols not only enhance the ability of coating to passivate protein-adsorption, but also make the coating have polyphenol-related biological functions. Therefore, the polyphenol and passivated protein-adsorption platform together maintain the stability of the scaffold microenvironment. This, in turn, provides favorable conditions for the growth of endothelial cells on the scaffold surface. In vivo implantation of the coated stents into the abdominal aorta resulted in uniform and dense endothelial cells covering the surface of the neointima. Moreover, new endothelial cells secreted large amounts of functional endothelial nitric oxide synthase like healthy endothelial cells. These results indicate that the polyphenol superhydrophilic coating potentially resists intra-stent restenosis and promotes surface reendothelialization. Hence, polyphenol superhydrophilic coatings with passivated protein-adsorption properties constructed by two-electron-assisted oxidation are a highly effective and versatile surface-modification strategy for implantable cardiovascular devices.

Method to obtain a plasma rich in platelet- and plasma-growth factors based on water evaporation

Platelet-Rich Plasma, also known as PRP, is an autologous biologic product used in medicine as a treatment for tissue repair. Nowadays, the majority of PRP obtention methods enrich only platelets, not considering extraplatelet biomolecules, which take part in several cell processes. In the present work, a novel PRP preparation method was developed to obtain a PRP rich in both platelet and plasma extraplatelet molecules. The method is based on the evaporation of the water of the plasma using a rotary evaporator. With this new methodology an increase in plasmatic growth factors and, as a consequence, a better dermal fibroblast cell viability was achieved, compared to a standard PRP formulation. This novel PRP product obtained with this new methodology showed promising results in vitro as an improved PRP treatment in future application.

Antifouling strategies for electrochemical sensing in complex biological media

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

Effect of Modification Strategies on the Biological Activity of Peptides/Proteins

Covalent attachment of biologically active peptides/proteins with functional moieties is an effective strategy to control their biodistribution, pharmacokinetics, enzymatic digestion, and toxicity. This review focuses on the characteristics of different modification strategies and their effects on the biological activity of peptides/proteins and illustrates their relevant applications and potential.

Recent Progress in antibacterial hydrogel coatings for targeting biofilm to prevent orthopedic implant-associated infections

The application of orthopedic implants for bone tissue reconstruction and functional restoration is crucial for patients with severe bone fractures and defects. However, the abiotic nature of orthopedic implants allows bacterial adhesion and colonization, leading to the formation of bacterial biofilms on the implant surface. This can result in implant failure and severe complications such as osteomyelitis and septic arthritis. The emergence of antibiotic-resistant bacteria and the limited efficacy of drugs against biofilms have increased the risk of orthopedic implant-associated infections (OIAI), necessitating the development of alternative therapeutics. In this regard, antibacterial hydrogels based on bacteria repelling, contact killing, drug delivery, or external assistance strategies have been extensively investigated for coating orthopedic implants through surface modification, offering a promising approach to target biofilm formation and prevent OIAI. This review provides an overview of recent advancements in the application of antibacterial hydrogel coatings for preventing OIAI by targeting biofilm formation. The topics covered include: (1) the mechanisms underlying OIAI occurrence and the role of biofilms in exacerbating OIAI development; (2) current strategies to impart anti-biofilm properties to hydrogel coatings and the mechanisms involved in treating OIAI. This article aims to summarize the progress in antibacterial hydrogel coatings for OIAI prevention, providing valuable insights and facilitating the development of prognostic markers for the design of effective antibacterial orthopedic implants.

Evaluation of stimbiotic on growth performance and intestinal development of broilers fed corn- or wheat-based diets

In the antibiotics-free era, stimbiotic (STB) has been suggested as a new alternative of antibiotic growth promoters to modulate intestinal health via stimulating dietary fiber utilization in poultry production. The aim of this study was to evaluate the effects of STB supplementation in corn- or wheat-basal diet on growth performance, intestinal development, and function of broilers. A total of 512 one-day-old Arbor Acres(AA)broilers were randomly allocated 4 treatments, including corn group (CG), corn + 100 g/t STB (CG + STB), wheat group (WG), wheat + 100 g/t STB (WG + STB). The broilers were weighed at the days of 14, 28, and 42, of which 8 repetitions per treatment were randomly selected to determine the intestinal morphology, intestinal barrier, and cecal microbiota and metabolites. Our data showed that STB increased (P < 0.05) feed intake, body weight and reduced FCR for the overall period (0-42 d). At 28 d of age, significant increases in villus height and the villus height-to-crypt depth ratio (V/C) were found in the STB supplementation groups (P < 0.05). Addition of STB significantly increased intestinal mucosal DAO and AMPK enzyme activity and the gene expression of OCLN, CLDN1, ZO1, MUC2, SGLT1, PEPT1, FABP2, Ghrelin, and GCG in jejunum (P < 0.05), and significantly decreased the expression of the PYY gene. In addition, STB increased the relative abundance of beneficial bacteria, such as Akkermansia, Bifidobacterium, and Oscillospirales (P < 0.05). A significant increase in cecal short-chain fatty acid (SCFAs) concentration was also observed in the STB supplementation groups. At the cellular level, STB cannot directly increase the expression of small intestinal epithelial cells, and may indirectly improve intestinal barrier function by increasing the level of sodium butyrate. Overall, these results indicated that STB supplementation could improve the growth performance, intestinal development and barrier functions, and fiber fermentation in cecum of broiler chickens.

An antifouling electrochemical biosensor based on chondroitin sulfate-functionalized polyaniline and DNA-peptide conjugates for cortisol determination in body fluids

An antifouling electrochemical biosensor was constructed based on chondroitin sulfate (CS)-functionalized polyaniline (CS/PANI) and DNA-peptide conjugates that is capable of assaying cortisol directly in human fluids. First, a CS-doped PANI nanocomposite (sensing substrate) was electrodeposited onto a bare glassy carbon electrode to promote electron transport, providing the sensing signal from high peak currents of PANI to improve the sensitivity of the biosensor. Dendritic DNA-peptide conjugates were assembled onto the CS/PANI by exploiting the highly specific and strong interactions between biotin and streptavidin, which amplified the sensing signals toward cortisol. The integration of the DNA-peptide conjugates into the CS/PANI nanocomposite ensured that the biosensor had a synergistic antifouling effect and was capable of detecting cortisol directly in body fluids (sweat, saliva, and tears). When assaying cortisol levels, the biosensor exhibited a linear range over the cortisol concentrations of 1 × 10-12-1 × 10-7 M and a low limit of detection (0.333 × 10-12 M). In the detection of cortisol in real samples, the relative standard deviation (RSD) of the biological samples ranged from 2.94 to 4.23%, and the recovery were calculated to be in the range 95.2-103.2%.

Ultrasensitive Ratiometric Electrochemiluminescence Sensor with an Efficient Antifouling and Antibacterial Interface of PSBMA@SiO2-MXene for Oxytetracycline Trace Detection in the Marine Environment

The sensitivity and accuracy of electrochemiluminescence (ECL) sensors for detecting small-molecule pollutants in environmental water are affected not only by nonspecific adsorption of proteins and other molecules but also by bacterial interference. Therefore, there is an urgent need to develop an ECL sensor with antifouling and antibacterial functions for water environment monitoring. Herein, a highly efficient antifouling sensing interface (PSBMA@SiO2-MXene) based on zwitterionic sulfobetaine methacrylate (SBMA) antifouling nanospheres (NPs) and two-dimensional MXene nanosheets was designed for the sensitive detection of oxytetracycline (OTC), an antibiotic small-molecule pollutant. Specifically, SBMA with good hydrophilicity and electrical neutrality was connected to SiO2 NPs, thus effectively reducing protein and bacterial adsorption and improving stability. Second, MXene with a high specific surface area was selected as the carrier to load more antifouling NPs, which greatly improves the antifouling performance. Meanwhile, the introduction of MXene also enhances the conductivity of the antifouling interface. In addition, a ratio-based sensing strategy was designed to further improve the detection accuracy and sensitivity of the sensor by utilizing Au@luminol as an internal standard factor. Based on antifouling and antibacterial interfaces, as well as internal standard and ratiometric sensing strategies, the detection range of the proposed sensor was 0.1 ng/mL to 100 μg/mL, with a detection limit of 0.023 ng/mL, achieving trace dynamic monitoring of antibiotics in complex aqueous media.

Enhancing activity of food protein-derived peptides: An overview of pretreatment, preparation, and modification methods

Food protein-derived peptides have garnered considerable attention due to their potential bioactivities and functional properties. However, the limited activity poses a challenge in effective utilization aspects. To overcome this hurdle, various methods have been explored to enhance the activity of these peptides. This comprehensive review offers an extensive overview of pretreatment, preparation methods, and modification strategies employed to augment the activity of food protein-derived peptides. Additionally, it encompasses a discussion on the current status and future prospects of bioactive peptide applications. The review also addresses the standardization of mass production processes and safety considerations for bioactive peptides while examining the future challenges and opportunities associated with these compounds. This comprehensive review serves as a valuable guide for researchers in the food industry, offering insights and recommendations to optimize the production process of bioactive peptides.

A bio-instructive parylene-based conformal coating suppresses thrombosis and intimal hyperplasia of implantable vascular devices

Implantable vascular devices are widely used in clinical treatments for various vascular diseases. However, current approved clinical implantable vascular devices generally have high failure rates primarily due to their surface lacking inherent functional endothelium. Here, inspired by the pathological mechanisms of vascular device failure and physiological functions of native endothelium, we developed a new generation of bioactive parylene (poly(p-xylylene))-based conformal coating to address these challenges of the vascular devices. This coating used a polyethylene glycol (PEG) linker to introduce an endothelial progenitor cell (EPC) specific binding ligand LXW7 (cGRGDdvc) onto the vascular devices for preventing platelet adhesion and selectively capturing endogenous EPCs. Also, we confirmed the long-term stability and function of this coating in human serum. Using two vascular disease-related large animal models, a porcine carotid artery interposition model and a porcine carotid artery-jugular vein arteriovenous graft model, we demonstrated that this coating enabled rapid generation of self-renewable "living" endothelium on the blood contacting surface of the expanded polytetrafluoroethylene (ePTFE) grafts after implantation. We expect this easy-to-apply conformal coating will present a promising avenue to engineer surface properties of "off-the-shelf" implantable vascular devices for long-lasting performance in the clinical settings.

Chemical antifouling strategies in sensors for food analysis: A review

Surface biofouling induced by the undesired nonspecific adsorption of foulants (e.g., coexisting proteins and cells) in food matrices is a major issue of sensors for food analysis, hindering their reliability and accuracy of sensing. This issue can be addressed by developing antifouling strategies to prevent or alleviate nonspecific binding. Chemical antifouling strategies involve the use of chemical modifiers (i.e., antifouling materials) to strongly hydrate the surface and reduce surface biofouling. Through appropriate immobilization approaches, antifouling materials can be tethered onto sensors to form antifouling surfaces with well-ordered structures, balanced surface charges, and appropriate surface density and thickness. A rational antifouling surface can reduce the matrix effect, simplify sample pretreatment, and improve analytical performance. This review summarizes recent developments in chemical antifouling strategies in sensing. Surface antifouling mechanisms and common antifouling materials are described, and factors that may influence the antifouling effects of antifouling surfaces and approaches incorporating antifouling materials onto sensing surfaces are highlighted. Moreover, the specific applications of antifouling sensors in food analysis are introduced. Finally, we provide an outlook on future developments in antifouling sensors for food analysis.

Biomimetic redox-responsive smart coatings with resistance-release functions for reverse osmosis membranes

Membrane fouling induces catastrophic loss of separation performance and seriously restricts the applications of reverse osmosis (RO) membranes. Inspired by the mussel structure, polydopamine (PDA) and cystamine molecules (CA) with excellent anti-fouling properties were used to prepare accessible, biocompatible, and redox-responsive coatings for RO membranes. The PDA/CA-coated RO membranes exhibit a superior water flux of 65 L m-2 h-1 with a favourable NaCl rejection exceeding 99%. The water permeability through the PDA/CA-coated membrane is much higher than that of most membranes with similar rejection rates. Due to the formed protective hydration layers by PDA/CA coatings, anti-fouling properties against proteins, polysaccharides and surfactants were evaluated separately, and ultralow fouling properties were demonstrated. Moreover, the disulfide linkages in CA molecules can cleave in a reducing environment, yielding the degradation of PDA/CA coatings, thereby removing the foulants deposited on the coatings. The degradation endows the coated membranes with satisfying longtime anti-fouling properties, where the flux recovery reaches up to 90%. The construction of redox-responsive smart coatings not only provided a promising route to alleviate membrane fouling but can also be upscaled for use in numerous practical applications like sensors, medical devices, and drug delivery.

Universal and One-Step Modification to Render Diverse Materials Bioactivation

Bioactive materials that can support cell adhesion and tissue regeneration are greatly in demand in clinical applications. Surface modification with bioactive molecules is an efficient strategy to convert conventional bioinert materials into bioactive materials. However, there is an urgent need to find a universal and one-step modification strategy to realize the above transformation for bioactivation. In this work, we report a universal and one-step modification strategy to easily modify and render diverse materials bioactivation by dipping materials into the solution of dibutylamine-DOPA-lysine-DOPA (DbaYKY) tripeptide-terminated cell-adhesive molecules, β-peptide polymer, or RGD peptide for only 5 min. This strategy provides materials with a stable surface modification layer and does not cause an undesired surface color change like the widely used polydopamine coating. This one-step strategy can endow material surfaces with cell adhesion properties without concerns on nonspecific conjugation of proteins and macromolecules. This universal and one-step surface bioactivation strategy implies a wide range of applications in implantable biomaterials.

Self-assembled nanoformulations of paclitaxel for enhanced cancer theranostics

Chemotherapy has occupied the critical position in cancer therapy, especially towards the post-operative, advanced, recurrent, and metastatic tumors. Paclitaxel (PTX)-based formulations have been widely used in clinical practice, while the therapeutic effect is far from satisfied due to off-target toxicity and drug resistance. The caseless multi-components make the preparation technology complicated and aggravate the concerns with the excipients-associated toxicity. The self-assembled PTX nanoparticles possess a high drug content and could incorporate various functional molecules for enhancing the therapeutic index. In this work, we summarize the self-assembly strategy for diverse nanodrugs of PTX. Then, the advancement of nanodrugs for tumor therapy, especially emphasis on mono-chemotherapy, combinational therapy, and theranostics, have been outlined. Finally, the challenges and potential improvements have been briefly spotlighted.

Modular Design for Proteins Assembling into Antifouling Coatings: Case of Gold Surfaces

We analyze modularity for a B-M-E triblock protein designed to self-assemble into antifouling coatings. Previously, we have shown that the design performs well on silica surfaces when B is taken to be a silica-binding peptide, M is a thermostable trimer domain, and E is the uncharged elastin-like polypeptide (ELP), E = (GSGVP)₄₀. Here, we demonstrate that we can modulate the nature of the substrate on which the coatings form by choosing different solid-binding peptides as binding domain B and that we can modulate antifouling properties by choosing a different hydrophilic block E. Specifically, to arrive at antifouling coatings for gold surfaces, as binding block B we use the gold-binding peptide GBP1 (with the sequence MHGKTQATSGTIQS), while we replace the antifouling blocks E by zwitterionic ELPs of different lengths, E^Z_n = (GDGVP-GKGVP)_n/2, with n = 20, 40, or 80. We find that even the B-M-E proteins with the shortest E blocks make coatings on gold surfaces with excellent antifouling against 1% human serum (HS) and reasonable antifouling against 10% HS. This suggests that the B-M-E triblock protein can be easily adapted to form antifouling coatings on any substrate for which solid-binding peptide sequences are available.

Streamlining the interface between electronics and neural systems for bidirectional electrochemical communication

Seamless neural interfaces conjoining neurons and electrochemical devices hold great potential for highly efficient signal transmission across neural systems and the external world. Signal transmission through chemical sensing and stimulation via electrochemistry is remarkable because communication occurs through the same chemical language of neurons. Emerging strategies based on synaptic interfaces, iontronics-based neuromodulation, and improvements in selective neurosensing techniques have been explored to achieve seamless integration and efficient neuro-electronics communication. Synaptic interfaces can directly exchange signals to and from neurons, in a similar manner to that of chemical synapses. Hydrogel-based iontronic chemical delivery devices are operationally compatible with neural systems for improved neuromodulation. In this perspective, we explore developments to improve the interface between neurons and electrodes by targeting neurons or sub-neuronal regions including synapses. Furthermore, recent progress in electrochemical neurosensing and iontronics-based chemical delivery is examined.

Serial intravital 2-photon microscopy and analysis of the kidney using upright microscopes

Serial intravital 2-photon microscopy of the kidney and other abdominal organs is a powerful technique to assess tissue function and structure simultaneously and over time. Thus, serial intravital microscopy can capture dynamic tissue changes during health and disease and holds great potential to characterize (patho-) physiological processes with subcellular resolution. However, successful image acquisition and analysis require significant expertise and impose multiple potential challenges. Abdominal organs are rhythmically displaced by breathing movements which hamper high-resolution imaging. Traditionally, kidney intravital imaging is performed on inverted microscopes where breathing movements are partly compensated by the weight of the animal pressing down. Here, we present a custom and easy-to-implement setup for intravital imaging of the kidney and other abdominal organs on upright microscopes. Furthermore, we provide image processing protocols and a new plugin for the free image analysis software FIJI to process multichannel fluorescence microscopy data. The proposed image processing pipelines cover multiple image denoising algorithms, sample drift correction using 2D registration, and alignment of serial imaging data collected over several weeks using landmark-based 3D registration. The provided tools aim to lower the barrier of entry to intravital microscopy of the kidney and are readily applicable by biomedical practitioners.

Effect of Mini-PEGs Modification on the Enzymatic Digestion of D-Amino Acid-Containing Peptides under the Action of PROK

It was previously reported that D-amino acid-containing peptides exhibited the ability to resist enzymatic hydrolysis. This study investigated the influence of mini-PEGs modification on enzymatic hydrolysis ability of D-amino acid-containing peptides. The results showed that PEGylation promoted enzymatic hydrolysis of the D-amino acid-containing peptide, especially, the cleavage rate of the D-amino acid-containing peptide 6-w with PEG₃ modification at the N-ends was up to 17 times higher in the presence of proteinase K (PROK) compared to those without PEG₃ modification. Moreover, analysis of the enzymatic cleavage sites demonstrated a similar cleavage pattern of the PEGylated D-amino acid-containing peptide to that of the unmodified peptide. The computational simulations further showed that the enhanced enzymatic hydrolysis ability can be attributed to the strong interaction between PROK and the peptide after PEG₃ modification and the resulting formation of a mature catalytic triad structure.

Surface decoration with leucine tetrapeptide: An antibacterial strategy against Gram-negative bacteria

Surface-associated microbe contamination by Gram-negative bacteria poses a serious problem in medical care. Cationic peptides or polymers are the main materials used for antibacterial surface coating, but the positive charge may lead to blood coagulation. Therefore, exploiting surface coating which is free of positive charge and is effective for Gram-negative bacteria inactivation is in urgent need. In this study, inspired by the affinity between lipopolysaccharides of Gram-negative bacteria and Toll-like receptors of immune cells, we develop a leucine-based tetrapeptide coating strategy for combating Gram-negative bacteria. The obtained surface has excellent bactericidal activity against Gram-negative bacteria like Pseudomonas aeruginosa and Escherichia coli. A 1 mm² coated glass surface could kill > 9.9 × 10⁴ CFU bacteria in 1 h and has nearly no damage to mammal cells. Moreover, this surface coating strategy could be applied on various surfaces like glass slices, glass capillary cavity and thermoplastic polyurethane slices. And the coated surface could largely mitigate the microbe contamination in an in vivo subcutaneous implantation. This work paves a new way for antibacterial surface-coating which is behaving no positive charge and is of great importance for biomedical devices.

A bio-orthogonally functionalized chitosan scaffold with esterase-activatable release for nerve regeneration

Developing nerve conduits with biological cues is a promising approach for repairing peripheral nerve injuries. Although most biological cues incorporated into conduits generally exert their biological functions at the surface, they could not be released into the on-demand regeneration sites under physiological conditions. Herein, we firstly report a bio-orthogonally functionalized chitosan scaffold with esterase-activatable release for peripheral nerve regeneration. In this study, biological cues are not only selectively conjugated into nerve conduits by bio-orthogonal reaction, but also precisely released in on-demand regeneration sites via esterase-activatable cleavage for peripheral nerve repair. Moreover, this nerve scaffold with esterase-activatable release could promote Schwann cells proliferation. In a rat sciatic nerve defect model, the bio-orthogonally functionalized scaffold with esterase-activatable release significantly increased sciatic nerve function recovery and improved target muscles weight. This strategy of incorporating esterase-activatable bioactive cues into peripheral nerve conduits offers great potential in preclinical studies.

Advance in the Polymerization Strategy for the Synthesis of β-Peptides and β-Peptoids

Peptide mimics, possessing excellent biocompatibility and protease stability, have attracted broad attention and research in the biomedical field. β-Peptides and β-peptoids, as two types of vital peptide mimics, have demonstrated great potential in the field of foldamers, antimicrobials and protein binding, etc. Currently, the main synthetic strategies for β-peptides and β-peptoids include solid-phase synthesis and polymerization. Among them, polymerization in one-pot can minimize the repeated separation and purification used in solid-phase synthesis, and has the advantages of high efficiency and low cost, and can synthesize β-peptides and β-peptoids with high molecular weight. This review summarizes the polymerization methods for β-peptides and β-peptoids. Moreover, future developments of the polymerization method for the synthesis of β-peptides and β-peptoids will be discussed.