Intrinsically Disordered Protein Condensate-Modified Surface for Mitigation of Biofouling and Foreign Body Response

Macrophage response to fibrin structure mediated by Tgm2-dependent mitochondrial mechanosensing

Following an injury at the implantation position, blood-material interactions form a fibrin architecture, which serves as the initial activator of foreign body response (FBR). However, there is limited knowledge regarding how the topography of fibrin architectures regulates macrophage behavior in mitigating FBR. Mechanical cues of the microenvironment have been reported to shape immune cell functions. Here, we investigated macrophage mechanobiology at the organelle level by constructing heterogeneous fibrin networks. Based on findings in vivo, we demonstrated that adhesion-mediated differentiation of mitochondrial function modulated macrophage polarization. The finite activation of integrin signaling upregulated transglutaminase 2 (Tgm2) in a trans-manner, augments PGC1α-mediated mitochondrial biogenesis. Our study highlighted the previously overlooked spatial structures of host proteins adsorbed on material surfaces, advocating for a paradigm shift in material design strategies, from focusing solely on physical properties to considering the modification of host proteins.

Decoding biomaterial-associated molecular patterns (BAMPs): influential players in bone graft-related foreign body reactions

Bone grafts frequently induce immune-mediated foreign body reactions (FBR), which hinder their clinical performance and result in failure. Understanding biomaterial-associated molecular patterns (BAMPs), including physicochemical properties of biomaterial, adsorbed serum proteins, and danger signals, is crucial for improving bone graft outcomes. Recent studies have investigated the role of BAMPs in the induction and maintenance of FBR, thereby advancing the understanding of FBR kinetics, triggers, stages, and key contributors. This review outlines the stages of FBR, the components of BAMPs, and their roles in immune activation. It also discusses various bone grafting biomaterials, their physicochemical properties influencing protein adsorption and macrophage modulation, and the key mechanisms of protein adsorption on biomaterial surfaces. Recent advancements in surface modifications and immunomodulatory strategies to mitigate FBR are also discussed. Furthermore, the authors look forward to future studies that will focus on a comprehensive proteomic analysis of adsorbed serum proteins, a crucial component of BAMPs, to identify proteins that promote or limit inflammation. This understanding could facilitate the design of biomaterials that selectively adsorb beneficial proteins, thereby reducing the risk of FBR and enhancing bone regeneration.

Electrochemical Biosensor Utilizing Low-Susceptibility Macrocyclic Stapled Peptide to Mitigate Biofouling for Reliable Protein Detection in Human Serum

Antifouling peptide surfaces have garnered increasing attention due to their immense potential across various biochemical fields. Cyclic peptides, in particular, demonstrate greater resistance to nonspecific substance adsorption compared to regular linear peptides. Herein, inspired by the macrocyclization method, we introduced two non-natural amino acids (R8 and S5) to cyclize the typical low-fouling sequence (EKEKEK) head-to-tail, thereby protecting terminal amino acids and reducing proteolytic susceptibility. This approach resulted in the formation of a novel stapled peptide (SP), which resisted protease hydrolysis and enhanced the antifouling capabilities of the SP-based biosensor compared to the conventional linear peptide (LP), demonstrated by electrochemical testing and fluorescence imaging experiments. Theoretically, molecular dynamics simulations were employed to calculate binding energies between the peptides and carboxypeptidase Y (CPY), and the results showcased a stronger binding affinity of LP with CPY, further confirming the lower proteolytic susceptibility of the engineered SP. Remarkably, the SP-based biosensor demonstrated high sensitivity in detecting the model target of carcinoembryonic antigen, with a limit of detection of 0.49 pg/mL. Moreover, clinical serum samples analyzed using the SP-based biosensor showed excellent concordance with hospital diagnostic methods, underscoring its exceptional accuracy and further highlighting the superiorities of the engineered SP structures.

Genome-Wide Characterization of Wholly Disordered Proteins in Arabidopsis

Intrinsically disordered proteins (IDPs) include two types of proteins: partial disordered regions (IDRs) and wholly disordered proteins (WDPs). Extensive studies focused on the proteins with IDRs, but less is known about WDPs because of their difficult-to-form folded tertiary structure. In this study, we developed a bioinformatics method for screening more than 50 amino acids in the genome level and found a total of 27 categories, including 56 WDPs, in Arabidopsis. After comparing with 56 randomly selected structural proteins, we found that WDPs possessed a more wide range of theoretical isoelectric point (PI), a more negative of Grand Average of Hydropathicity (GRAVY), a higher value of Instability Index (II), and lower values of Aliphatic Index (AI). In addition, by calculating the FCR (fraction of charged residue) and NCPR (net charge per residue) values of each WDP, we found 20 WDPs in R1 (FCR < 0.25 and NCPR < 0.25) group, 15 in R2 (0.25 ≤ FCR ≤ 0.35 and NCPR ≤ 0.35), 19 in R3 (FCR > 0.35 and NCPR ≤ 0.35), and two in R4 (FCR > 0.35 and NCPR > 0.35). Moreover, the gene expression and protein-protein interaction (PPI) network analysis showed that WDPs perform different biological functions. We also showed that two WDPs, SIS (Salt Induced Serine rich) and RAB18 (a dehydrin family protein), undergo the in vitro liquid-liquid phase separation (LLPS). Therefore, our results provide insight into understanding the biochemical characters and biological functions of WDPs in plants.

Dynamic Peptide Nanoframework-Guided Protein Coassembly: Advancing Adhesion Performance with Hierarchical Structures

Hierarchical structures are essential in natural adhesion systems. Replicating these in synthetic adhesives is challenging due to intricate molecular mechanisms and multiscale processes. Here, we report three phosphorylated peptides featuring a hydrophobic self-assembly motif linked to a hydrophilic phosphorylated sequence (pSGSS), forming peptide fibril nanoframeworks. These nanoframeworks effectively coassemble with elastin-derived positively charged proteins (PCP), resulting in complex coacervate-based adhesives with hierarchical structures. Our method enables the controlled regulation of both cohesion and adhesion properties in the adhesives. Notably, the complex adhesives formed by the dityrosine-containing peptide and PCP demonstrate an exceptional interfacial adhesion strength of up to 30 MPa, outperforming most known supramolecular adhesives and rivaling cross-linked chemical adhesives. Additionally, these adhesives show promising biocompatibility and bioactivity, making them suitable for applications such as visceral hemostasis and tissue repair. Our findings highlight the utility of bioinspired hierarchical assembly combined with bioengineering techniques in advancing biomedical adhesives.

Harnessing Nature-Inspired Catechol Amino Acid to Engineer Sticky Proteins and Bacteria

3,4-Dihydroxy-L-phenylalanine (DOPA) serves as a post-translational modification amino acid present in mussel foot proteins. Mussels exploit the exceptional adhesive properties of DOPA to adhere to a wide range of surfaces. This study presents the development of sticky proteins and bacteria through the site-specific incorporation of DOPA using Genetic Code Expansion Technology. Through the optimization of the DOPA incorporation system, proteins containing DOPA demonstrate significantly improved binding abilities to various organic and metallic materials. The material-binding capabilities of DOPA to combat different types of biofoulings are harnessed by integrating it into intrinsically disordered proteins. Beyond the creation of adhesive proteins for anti-biofouling purposes, this highly efficient DOPA incorporation system is also applied to engineer adhesive bacteria, resulting in a remarkable increase in their binding capability to diverse materials including 400 folds of improvement to polyethylene terephthalate (PET). This substantial enhancement in PET binding of these bacteria has allowed to develop a unique approach for PET degradation, showcasing the innovative application of Genetic Code Expansion in cell engineering.

Data-Driven Materials Research and Development for Functional Coatings

Functional coatings, including organic and inorganic coatings, play a vital role in various industries by providing a protective layer and introducing unique functionalities. However, its design often involves time-consuming experimentation with multiple materials and processing parameters. To overcome these limitations, data-driven approaches are gaining traction in materials science. In this paper, recent advances in data-driven materials research and development (R&D) for functional coatings, highlighting the importance, data sources, working processes, and applications of this paradigm are summarized. It is begun by discussing the challenges of traditional methods, then introduce typical data-driven processes. It is demonstrated how data-driven approaches enable the identification of correlations between input parameters and coating performance, thus allowing for efficient prediction and design. Furthermore, carefully selected case studies are presented across diverse industries that exemplify the effectiveness of data-driven methods in accelerating the discovery of new functional coatings with tailored properties. Finally, the emerging research directions, involving integrating advanced techniques and data from different sources, are addressed. Overall, this review provides an overview of data-driven materials R&D for functional coatings, shedding light on its potential and future developments.

A Nonfouling Electrochemical Biosensor for Protein Analysis in Complex Body Fluids Based on Multifunctional Peptide Conjugated with PEGlyated Phospholipid

Developing antifouling biosensors capable of performing robustly in complex human body fluids is crucial for biomarker diagnosis and health monitoring. Herein, an antifouling and highly sensitive and stable biosensor was constructed through the self-assembly of the designed conjugates composed of a multifunctional peptide (MP) and PEGylated distearoylphosphatidylethanolamine (DSPE-PEG). The self-assembly capability of the DSPE-PEG-MP was demonstrated clearly through coarse-grained molecular dynamics simulation and transmission electron microscopy, and it can be effectively self-assembled onto the electrode surface modified with gold nanoparticles. The MP was designed to be antifouling and contained a peptide sequence that can specifically bind the target protein Annexin A1 (ANXA1), and the D-type amino acid composition of MP can enhance its resistance to enzymatic hydrolysis. The unique design of MP, in conjugation with the self-assembly capability of the PEGylated phospholipid DSPE-PEG, enabled the biosensor to exhibit excellent antifouling capability and stability in various complex human body fluids. The biosensor was capable of sensitively and selectively quantifying ANXA1 and achieved a limit of detection down to 0.12 pg mL-1. More importantly, the biosensor demonstrated satisfactory accuracy for ANXA1 detection in clinical serum samples, as verified by the enzyme linked immunosorbent assay (ELISA) kits. It is expected that various antifouling biosensors suitable for application in complex biological environments can be constructed by utilizing the strategy of designing similar DSPE-PEG-MP conjugates.

An elastomer with in situ generated pure zwitterionic surfaces for fibrosis-resistant implants

Polymeric elastomers are widely utilized in implantable biomedical devices. Nevertheless, the implantation of these elastomers can provoke a robust foreign body response (FBR), leading to the rejection of foreign implants and consequently reducing their effectiveness in vivo. Building effective anti-FBR coatings on those implants remains challenging. Herein, we introduce a coating-free elastomer with superior immunocompatibility. A super-hydrophilic anti-fouling zwitterionic layer can be generated in situ on the surface of the elastomer through a simple chemical trigger. This elastomer can repel the adsorption of proteins, as well as the adhesion of cells, platelets, and diverse microbes. The elastomer elicited negligible inflammatory responses after subcutaneous implantation in rodents for 2 weeks. No apparent fibrotic capsule formation was observed surrounding the elastomer after 6 months in rodents. Continuous subcutaneous insulin infusion (CSII) catheters constructed from the elastomer demonstrated prolonged longevity and performance compared to commercial catheters, indicating its great potential for enhancing and extending the performance of various implantable biomedical devices by effectively attenuating local immune responses. STATEMENT OF SIGNIFICANCE: The foreign body response remains a significant challenge for implants. Complicated coating procedures are usually needed to construct anti-fibrotic coatings on implantable elastomers. Herein, a coating-free elastomer with superior immunocompatibility was achieved using a zwitterionic monomer derivative. A pure zwitterionic layer can be generated on the elastomer surface through a simple chemical trigger. This elastomer significantly reduces protein adsorption, cell and bacterial adhesion, and platelet activation, leading to minimal fibrotic capsule formation even after six months of subcutaneous implantation in rodents. CSII catheters constructed from the PQCBE-H elastomer demonstrated prolonged longevity and performance compared to commercial catheters, highlighting the significant potential of PQCBE-H elastomers for enhancing and extending the performance of various implantable biomedical devices.

Self-assembled branched polypeptides as amelogenin mimics for enamel repair

The regeneration of demineralized enamel holds great significance in the treatment of dental caries. Amelogenin (Ame), an essential protein for mediating natural enamel growth, is no longer secreted after enamel has fully matured in childhood. Although biomimetic mineralization based on peptides or proteins has made significant progress, easily accessible, low-cost, biocompatible and highly effective Ame mimics are still lacking. Herein, we construct a series of amphiphilic branched polypeptides (CAMPs) by facile coupling of the Ame's C-terminal segment and poly(γ-benzyl-L-glutamate), which serves to simulate the Ame's hydrophobic N-terminal segment. Among them, CAMP15 is the best biomimetic mineralization template with great self-assembly performance to guide the oriented crystallization of hydroxyapatite and is capable of inhibiting the adhesion of Streptococcus mutans and Staphylococcus aureus on the enamel surfaces. This work highlights the potential application of amphiphilic branched polypeptide as Ame mimics in repairing defected enamel, providing a promising strategy for prevention and treatment of dental caries.

Materials Strategies to Overcome the Foreign Body Response

The foreign body response (FBR) is an immune-mediated reaction that can occur with most biomaterials and biomedical devices. The FBR initiates a deterioration in the performance of implantable devices, representing a longstanding challenge that consistently hampers their optimal utilization. Over the last decade, significant strides are achieved based on either hydrogel design or surface modifications to mitigate the FBR. This review delves into recent material strategies aimed at mitigating the FBR. Further, the authors look forward to future novel anti-FBR materials from the perspective of clinical translation needs. Such prospective materials hold the potential to attenuate local immune responses, thereby significantly enhancing the overall performance of implantable devices.

The tardigrade-derived mitochondrial abundant heat soluble protein improves adipose-derived stem cell survival against representative stressors

Human adipose-derived stem cell (ASC) grafts have emerged as a powerful tool in regenerative medicine. However, ASC therapeutic potential is hindered by stressors throughout their use. Here we demonstrate the transgenic expression of the tardigrade-derived mitochondrial abundant heat soluble (MAHS) protein for improved ASC resistance to metabolic, mitochondrial, and injection shear stress. In vitro, MAHS-expressing ASCs demonstrate up to 61% increased cell survival following 72 h of incubation in phosphate buffered saline containing 20% media. Following up to 3.5% DMSO exposure for up to 72 h, a 14-49% increase in MAHS-expressing ASC survival was observed. Further, MAHS expression in ASCs is associated with up to 39% improved cell viability following injection through clinically relevant 27-, 32-, and 34-gauge needles. Our results reveal that MAHS expression in ASCs supports survival in response to a variety of common stressors associated with regenerative therapies, thereby motivating further investigation into MAHS as an agent for stem cell stress resistance. However, differentiation capacity in MAHS-expressing ASCs appears to be skewed in favor of osteogenesis over adipogenesis. Specifically, activity of the early bone formation marker alkaline phosphatase is increased by 74% in MAHS-expressing ASCs following 14 days in osteogenic media. Conversely, positive area of the neutral lipid droplet marker BODIPY is decreased by up to 10% in MAHS-transgenic ASCs following 14 days in adipogenic media. Interestingly, media supplementation with up to 40 mM glucose is sufficient to restore adipogenic differentiation within 14 days, prompting further analysis of mechanisms underlying interference between MAHS and differentiation processes.

Enzymatic Galvanic Redox Potentiometry for In Vivo Biosensing

Redox potentiometry has emerged as a new platform for in vivo sensing, with improved neuronal compatibility and strong tolerance against sensitivity variation caused by protein fouling. Although enzymes show great possibilities in the fabrication of selective redox potentiometry, the fabrication of an enzyme electrode to output open-circuit voltage (EOC) with fast response remains challenging. Herein, we report a concept of novel enzymatic galvanic redox potentiometry (GRP) with improved time response coupling the merits of the high selectivity of enzyme electrodes with the excellent biocompatibility and reliability of GRP sensors. With a glucose biosensor as an illustration, we use flavin adenine dinucleotide-dependent glucose dehydrogenase as the recognition element and carbon black as the potential relay station to improve the response time. We find that the enzymatic GRP biosensor rapidly responds to glucose with a good linear relationship between EOC and the logarithm of glucose concentration within a range from 100 μM to 2.65 mM. The GRP biosensor shows high selectivity over O2 and coexisting neurochemicals, good reversibility, and sensitivity and can in vivo monitor glucose dynamics in rat brain. We believe that this study will pave a new platform for the in vivo potentiometric biosensing of chemical events with high reliability.

Protein-based bioactive coatings: from nanoarchitectonics to applications

Protein-based bioactive coatings have emerged as a versatile and promising strategy for enhancing the performance and biocompatibility of diverse biomedical materials and devices. Through surface modification, these coatings confer novel biofunctional attributes, rendering the material highly bioactive. Their widespread adoption across various domains in recent years underscores their importance. This review systematically elucidates the behavior of protein-based bioactive coatings in organisms and expounds on their underlying mechanisms. Furthermore, it highlights notable advancements in artificial synthesis methodologies and their functional applications in vitro. A focal point is the delineation of assembly strategies employed in crafting protein-based bioactive coatings, which provides a guide for their expansion and sustained implementation. Finally, the current trends, challenges, and future directions of protein-based bioactive coatings are discussed.

Fibrous capsule-resistant, controllably degradable and functionalizable zwitterion-albumin hybrid hydrogels

Foreign body response (FBR) represents an immune-mediated cascade reaction capable of inducing the rejection of foreign implants, thereby compromising their in vivo performance. Pure zwitterionic hydrogels have demonstrated the ability to resist long-term FBR, owing to their outstanding antifouling capabilities. However, achieving such a robust anti-FBR effect necessitates stringent requirements concerning the purity of zwitterionic materials, which constrains their broader functional applications. Herein, we present a biocompatible, controllably degradable, and functionalizable zwitterion-albumin hybrid hydrogel. The zwitterionic hydrogel crosslinked with serum albumin exhibits controllable degradation and excels in preventing the adsorption of various proteins and adhesion of cells and bacteria. Moreover, the hydrogel significantly alleviates the host's FBR compared with PEG hydrogels and particularly outperforms PEG-based cross-linker crosslinked zwitterionic hydrogels in reducing collagen encapsulation when subcutaneously implanted into mice. The zwitterion-albumin hybrid hydrogel shows potential as a functionalizable anti-FBR material in the context of implantable materials and biomedical devices.

Engineered Branching Peptide as Dual-Functional Antifouling and Recognition Probe: Toward a Dual-Photoelectrode Protein Biosensor with High Accuracy

The building of practical biosensors that have anti-interference abilities against biofouling of nonspecific proteins and biooxidation of reducing agents in actual biological matrixes remains a great challenge. Herein, a robust photoelectrochemical (PEC) biosensor capable of accurate detection in human serum was pioneered through the integration of a new engineered branching peptide (EBP) into a synergetic dual-photoelectrode system. The synergetic dual-photoelectrode system involved the tandem connection of a C3N4/TiO2 photoanode and a AuPt/PANI photocathode, while the EBP as a dual-functional antifouling and recognition probe featured an inverted Y-shaped configuration with one recognition backbone and two antifouling branches. Such an EBP enables a simple procedure for electrode modification and an enhanced antifouling nature compared to a regular linear peptide (LP), as theoretically supported by the results from molecular dynamics simulations. The as-developed PEC biosensor had a higher photocurrent response and a good antioxidation property inherited from the photoanode and photocathode, respectively. Targeting the model protein biomarker of cardiac troponin I (cTnI), this biosensor achieved good performances in terms of high sensitivity, specificity, and anti-interference.

An electrochemical biosensor for HER2 detection in complex biological media based on two antifouling materials of designed recognizing peptide and PEG

A simple tactic for electrochemical determination of a typical biomarker for breast cancer, human epidermal growth factor receptor 2 (HER2), was presented via the construction of a low fouling sensing interface functionalized with polyethylene glycol (PEG) and peptide. The HER2 biosensor was developed based on an electrode modified by the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and Au nanoparticles (AuNPs) as the sensing substrate, and followed by the immobilization of an antifouling PEG and a peptide with both recognizing and antifouling properties. Thanks to the combined antifouling effect of the PEG and peptide, and the specific recognizing ability of the peptide to the target HER2, the developed electrochemical biosensor exhibited strong antifouling performances in complex biofluids, such as human blood and serum, and it was capable of assaying target HER2 within a very wide linear range (1.0 pg mL^-1 to 1.0 μg mL^-1), with an ultralow limit of detection (0.44 pg mL^-1). The combination of two kinds of antifouling biomaterials (PEG and peptide) offered an effective strategy for the development of low fouling sensing platforms suitable for practical assay in complex biotic environments.

Hydrophilic surface-modified 3D printed flexible scaffolds with high ceramic particle concentrations for immunopolarization-regulation and bone regeneration

Bioceramic scaffolds used in bone tissue engineering suffer from a low concentration of ceramic particles (<50 wt%), because the high concentration of ceramic particles increases the brittleness of the composite. 3D printed flexible PCL/HA scaffolds with high ceramic particle concentrations (84 wt%) were successfully fabricated in this study. However, the hydrophobicity of PCL weakens the composite scaffold hydrophilicity, which may limit the osteogenic ability to some extent. Thus, as a less time-consuming, less labour intensive, and more cost-effective treatment method, alkali treatment (AT) was employed to modify the surface hydrophilicity of the PCL/HA scaffold, and its regulation of immune responses and bone regeneration were investigated in vivo and in vitro. Initially, several concentrations of NaOH (0.5, 1, 1.5, 2, 2.5, and 5 mol L^-1) were employed in tests to determine the appropriate concentration for AT. Based on the comprehensive consideration of the results of mechanical experiments and hydrophilicity, 2 mol L^-1 and 2.5 mol L^-1 of NaOH were selected for further investigation in this study. The PCL/HA-AT-2 scaffold dramatically reduced foreign body reactions as compared to the PCL/HA and PCL/HA-AT-2.5 scaffolds, promoted macrophage polarization towards the M2 phenotype and enhanced new bone formation. The Wnt/β-catenin pathway might participate in the signal transduction underlying hydrophilic surface-modified 3D printed scaffold-regulated osteogenesis, according to the results of immunohistochemical staining. In conclusion, hydrophilic surface-modified 3D printed flexible scaffolds with high ceramic particle concentrations can regulate the immune reactions and macrophage polarization to promote bone regeneration, and the PCL/HA-AT-2 scaffold is a potential candidate for bone tissue repair.

Hydrogel-Coated Microelectrode Resists Protein Passivation of In Vivo Amperometric Sensors

Passivation of electrodes caused by nonspecific adsorption of protein can dramatically reduce sensing sensitivity and accuracy, which is a great challenge for in vivo neurochemical monitoring. However, most antipassivation strategies are not suitable to carbon fiber microelectrodes (CFMEs) for in vivo measurement, and these methods also do not work on electrochemical biosensors that fix biometric elements. In this study, we demonstrate that chitosan hydrogel-coated microelectrodes can avoid the current passivation caused by protein adsorption on the surface of carbon fiber because the chitosan hydrogel prepared by local pH gradient caused by hydrogen evolution reaction has three-dimensional networks containing large amounts of water. The highly hydrophilic three-dimensional structure of hydrogel not only forms a biocompatible interface to confine enzymes but also keeps the fast mass transfer of analytes, such as dopamine, ascorbic acid, and glucose. The consistency of the precalibration and postcalibration of the prepared sensor enables in vivo amperometric detection of both electroactive species based on their redox property and electroinactive species based on the enzyme. This study provides a simple and versatile strategy to constitute an amperometric sensor interface to resist passivation of protein adsorption in a complex biological environment such as the brain.

Recent advances in prevention, detection and treatment in prosthetic joint infections of bioactive materials

Prosthetic joint infection (PJI) is often considered as one of the most common but catastrophic complications after artificial joint replacement, which can lead to surgical failure, revision, amputation and even death. It has become a worldwide problem and brings great challenges to public health systems. A small amount of microbe attaches to the graft and forms a biofilm on its surface, which lead to the PJI. The current standard methods of treating PJI have limitations, but according to recent reports, bioactive materials have potential research value as a bioactive substance that can have a wide range of applications in the field of PJI. These include the addition of bioactive materials to bone cement, the use of antibacterial and anti-fouling materials for prosthetic coatings, the use of active materials such as bioactive glasses, protamine, hydrogels for prophylaxis and detection with PH sensors and fluorescent-labelled nanoparticles, and the use of antibiotic hydrogels and targeting delivery vehicles for therapeutic purposes. This review focus on prevention, detection and treatment in joint infections with bioactive materials and provide thoughts and ideas for their future applications.