Silk fibroin based wearable electrochemical sensors with biomimetic enzyme-like activity constructed for durable and on-site health monitoring

From discoloration to color enhancement: A novel approach to high-concentration tannic acid detection based on VCo-N-C bimetallic Nanozyme

The direct and rapid detection of high-concentration tannic acid (TA) was crucial for food quality monitoring. In this study, a TA detection system was developed based on a binary metal V and Co-enclosed carbon substrate (VCo-N-C) nanozyme with laccase-like activity, which innovatively shifted the conventional detection approach from the 3,3',5,5'-tetramethylbenzidine (TMB) discoloration principle to the 4-aminoantipyrine(4-AP) color enhancement principle. In the presence of VCo-N-C, 4-AP specifically bound to the oxidation products of TA, resulting in a brown-red compound. The sensing platform reduced the reaction time to 10 min and extended the detection range to 0.1-3000 mg/L (R2 > 0.99). Ultimately, the VCo-N-C&4-AP system was successfully applied to detect TA content in high-concentration actual samples such as brandy, white liquor, and tea beverages without the need of pretreatment. This study provided a new and powerful strategy for food quality control and monitoring.

High-sensitivity flexible electrochemical sensor for real-time multi-analyte sweat analysis

Flexible sweat sensors play a crucial role in health monitoring and disease prevention by enabling real-time, non-invasive assessment of human physiological conditions. Sweat contains a variety of biomarkers, offering valuable insights into an individual's health status. In this study, we developed an advanced flexible electrochemical sensor featuring reduced graphene oxide (rGO)-based electrodes, modified with a composite material comprising nitrogen and sulfur co-doped holey graphene (HG) and MXene, with in-situ-grown TiO2 nanoparticles on the MXene. The sensor design leverages the synergistic properties of its components: MXene provides a conductive scaffold, TiO2 enhances electrocatalytic activity, and the porous HG network facilitates efficient ion and electron transfer, with doping increasing the number of active sites. This configuration enables sensitive and simultaneous detection of ascorbic acid (AA), uric acid (UA), and dopamine (DA). Additionally, a potassium-selective (K⁺) film applied to rGO-enhanced electrodes supports concurrent detection of K⁺ in sweat. The sensor array demonstrates a broad detection range, low detection limits, and high sensitivity, while maintaining mechanical flexibility, anti-interference capabilities, and repeatability. Validated through in-situ sweat biomarker detection during exercise, the sensor effectively tracked fluctuations in K⁺, AA, and UA levels in a volunteer. This practical application underscores the sensor's potential for continuous health monitoring, and early disease detection, establishing it as a promising tool in modern healthcare.

Multifunctional applications of silk fibroin in biomedical engineering: A comprehensive review on innovations and impact

Silk fibroin (SF) is a biomaterial naturally produced by certain insects (notably silkworms), animals such as spiders, or through recombinant methods in genetically modified organisms. Its exceptional mechanical properties, biocompatibility, degradability, and bioactivity have inspired extensive research. In biomedicine, SF has been utilized in various forms, including gels, membranes, microspheres, and more. It also demonstrates versatility for applications across medical devices, regenerative medicine, tissue engineering, and related fields. This review explores the current research status, advantages, limitations, and potential application pathways of SF in biomedical engineering. The objective is to stimulate innovative ideas and perspectives for research and applications involving silk.

Metal-Protein Hybrid Materials: Unlocking New Frontiers in Biomedical Applications

Metal-protein hybrid materials represent a novel class of functional materials that exhibit exceptional physicochemical properties and tunable structures, rendering them remarkable applications in diverse fields, including materials engineering, biocatalysis, biosensing, and biomedicine. The design and development of multifunctional and biocompatible metal-protein hybrid materials have been the subject of extensive research and a key aspiration for practical applications in clinical settings. This review provides a comprehensive analysis of the design strategies, intrinsic properties, and biomedical applications of these hybrid materials, with a specific emphasis on their potential in cancer therapy, drug and vaccine delivery, antibacterial treatments, and tissue regeneration. Through rational design, stable metal-protein hybrid materials can be synthesized using straightforward methods, enabling them with therapeutic, delivery, immunomodulatory, and other desired functionalities. Finally, the review outlines the existing limitations and challenges associated with metal-protein hybrid materials and evaluates their potential for clinical translation, providing insights into their practical implementation within biomedical applications.

Potential of Nature-derived Biopolymers for Oral Applications- A Mini-Review

In recent years, there has been a growing emphasis on the "back-to-nature" movement, which has brought biopolymers derived from natural sources into the spotlight. These biopolymers are gaining attention for their versatile surface-active properties, anti-adhesive capabilities, excellent biocompatibility, non-toxicity, biodegradability, and antimicrobial effectiveness against a wide range of oral microorganisms, including both bacteria and fungi. Researchers have been actively modifying these eco-friendly, nature-based biopolymers to enhance their interaction with surrounding cells and tissues, improving their performance in vivo. This has led to innovative applications in areas such as surface coatings, controlled drug delivery, tissue repair, and dental implant devices. These advancements hold the potential to pave the way for the development of novel drug delivery systems with enhanced therapeutic properties, ultimately supporting the creation of innovative formulations for clinical use. This review aims to provide an up-to-date overview of recent developments, explore potential future directions, and highlight the promising applications of nature-derived biopolymers in oral healthcare.

Hybrid layer-by-layer assembly of AuNPs/NSF composite for electrochemical detection of miRNA-196a

Detection of microRNA-196a (miRNA-196a) is crucial in cancer research, enabling early diagnosis and providing guidance for individualized treatment. In this work, we employed a naturally occurring negatively charged nano silk fibroin (NSF) with high mechanical properties, biocompatibility, and conductivity to be encapsulated with a positively charged gold nanoparticles (AuNPs) were used as film-forming materials for electrostatic layer-by-layer self-assembly to modify the working electrode of the screen-printed carbon electrode (SPCE). Under the optimized experimental conditions, the uniformly distributed AuNPs on the surface of the multilayer film modified SPCE (AuNPs/NSF)5.5/SPCE combined with the sulfhydryl-modified capture probe cp-DNA through gold-sulfur bonds. Furthermore, miRNA-196a is specifically captured through complementary base pairing to achieve highly sensitive and specific detection. (AuNPs/NSF)5.5/SPCE electrode can detect miRNA-196a in a concentration range of 1.0 × 10-13 to 1.0 × 10-6 M, and the calculated detection limit is 4.63 × 10-14 M when the signal-to-noise ratio is 3. The obtained results showed that the (AuNPs/NSF)5.5/SPCE has excellent selectivity and good stability over time.

Application of Silk Light Chain on a Graphene Composite Surface: A Molecular Dynamics and Electrochemical Experiment

The surface functionalization of pristine graphene (PG) with beneficial biocomposites is important for biomedical and tissue engineering. This study introduces silk light chain as novel biocomposites to increase the biocompatibility of PG. We explored the supramolecular structures of the silk heavy and light chains. Through molecular dynamics, we compared and analyzed the structural effects and binding mechanisms of these domains in their interaction with PG. Our results highlighted a significant hydrophobic interaction between the silk light chain and PG, without structural collapse. The supramolecular structure of the silk light chain was identified by analyzing the amino acids bound to PG. Moreover, using the silk light chain, the hydrophobic surface of PG has changed to a hydrophilic surface, and the silk light-chain-PG electron transfer rate was evaluated for the graphene congeners: graphene oxide (GO) and reduced graphene oxide. Therefore, we are confident that the dispersibility and biocompatibility of PG can be increased using silk light chains, which will contribute to broadening the field of application of PG-based materials.

Tear-Based Ocular Wearable Biosensors for Human Health Monitoring

Wearable tear-based biosensors have garnered substantial interest for real time monitoring with an emphasis on personalized health care. These biosensors utilize major tear biomarkers such as proteins, lipids, metabolites, and electrolytes for the detection and recording of stable biological signals in a non-invasive manner. The present comprehensive review delves deep into the tear composition along with potential biomarkers that can identify, monitor, and predict certain ocular diseases such as dry eye disease, conjunctivitis, eye-related infections, as well as diabetes mellitus. Recent technologies in tear-based wearable point-of-care medical devices, specifically the state-of-the-art and prospects of glucose, pH, lactate, protein, lipid, and electrolyte sensing from tear are discussed. Finally, the review addresses the existing challenges associated with the widespread application of tear-based sensors, which will pave the way for advanced scientific research and development of such non-invasive health monitoring devices.

Advanced nanomaterials for electrochemical sensors: application in wearable tear glucose sensing technology

In the last few decades, tear-based biosensors for continuous glucose monitoring (CGM) have provided new avenues for the diagnosis of diabetes. The tear CGMs constructed from nanomaterials have been extensively demonstrated by various research activities in this field and are gradually witnessing their most prosperous period. A timely and comprehensive review of the development of tear CGMs in a compartmentalized manner from a nanomaterials perspective would greatly broaden this area of research. However, to our knowledge, there is a lack of specialized reviews and comprehensive cohesive reports in this area. First, this paper describes the principles and development of electrochemical glucose sensors. Then, a comprehensive summary of various advanced nanomaterials recently reported for potential applications and construction strategies in tear CGMs is presented in a compartmentalized manner, focusing on sensing properties. Finally, the challenges, strategies, and perspectives used to design tear CGM materials are emphasized, providing valuable insights and guidance for the construction of tear CGMs from nanomaterials in the future.

Recent research progress of selenotungstate-based biomolecular sensing materials

Polyoxometalates (POMs) have drawn significant attention on account of their structural designability, compositional diversity and great potential applications. As an indispensable branch of POMs, selenotungstates (SeTs) have been synthesized extensively. Some SeTs have been applied as sensing materials for detecting biomarkers (e.g., metabolites, hormones, cancer markers). To gain a comprehensive understanding of advancements in SeT-based sensing materials, we present an overview that encapsulates the sensing performances and mechanisms of SeT-based biosensors. SeT-based biosensors are categorized into electrochemical catalytic biosensors, electrochemical affinity biosensors, "turn-off" fluorescence biosensors and "turn-on" fluorescence biosensors. We anticipate the expansive potential of SeT-based biosensors in wearable and implantable sensing technologies, which promises to catalyze significant breakthroughs in SeT-based biosensors.

Kirigami triboelectric spider fibroin microneedle patches for comprehensive joint management

Joint injuries are among the leading causes of disability. Present concentrations were focused on oral drugs and surgical treatment, which brings severe and unnecessary difficulties for patients. Smart patches with high flexibility and intelligent drug control-release capacity are greatly desirable for efficient joint management. Herein, we present a novel kirigami spider fibroin-based microneedle triboelectric nanogenerator (KSM-TENG) patch with distinctive features for comprehensive joint management. The microneedle patch consists of two parts: the superfine tips and the flexible backing base, which endow it with great mechanical strength to penetrate the skin and enough flexibility to fit different bends. Besides, the spider fibroin-based MNs served as a positive triboelectric material to generate electrical stimulation, thereby forcing drug release from needles within 720 min. Especially, kirigami structures could also transform the flat patch into three dimensions, which could impart the patch with flexible properties to accommodate the complicated processes produced by joint motion. Benefiting from these traits, the KSM-TENG patch presents excellent performance in inhibiting the inflammatory response and promoting wound healing in mice models. The results indicated that the mice possessed only 2% wound area and the paw thickness was reduced from 10.5 mm to 6.2 mm after treatment with the KSM-TENG patch, which further demonstrates the therapeutic effect of joints in vivo. Thus, it is believed that the proposed novel KSM-TENG patch is valuable in the field of comprehensive treatments and personalized clinical applications.

Silk-based wearable devices for health monitoring and medical treatment

Previous works have focused on enhancing the tensile properties, mechanical flexibility, biocompatibility, and biodegradability of wearable devices for real-time and continuous health management. Silk proteins, including silk fibroin (SF) and sericin, show great advantages in wearable devices due to their natural biodegradability, excellent biocompatibility, and low fabrication cost. Moreover, these silk proteins possess great potential for functionalization and are being explored as promising candidates for multifunctional wearable devices with sensory capabilities and therapeutic purposes. This review introduces current advancements in silk-based constituents used in the assembly of wearable sensors and adhesives for detecting essential physiological indicators, including metabolites in body fluids, body temperature, electrocardiogram (ECG), electromyogram (EMG), pulse, and respiration. SF and sericin play vital roles in addressing issues related to discomfort reduction, signal fidelity improvement, as well as facilitating medical treatment. These developments signify a transition from hospital-centered healthcare toward individual-centered health monitoring and on-demand therapeutic interventions.

Integrated Sandwich-Paper 3D Cell Sensing Device to In Situ Wirelessly Monitor H2O2 Released from Living Cells

Point-of-care testing (POCT) has attracted great interest because of its prominent advantages of rapidness, precision, portability, and real-time monitoring, thus becoming a powerful biomedical device in early clinical diagnosis and convenient medical treatments. However, its complicated manufacturing process and high expense severely impede mass production and broad applications. Herein, an innovative but inexpensive integrated sandwich-paper three-dimensional (3D) cell sensing device is fabricated to in situ wirelessly detect H2O2 released from living cells. The paper-based electrochemical sensing device was constructed by a sealed sandwiched bottom plastic film/fiber paper/top hole-centered plastic film that was printed with patterned electrodes. A new (Fe, Mn)3(PO4)2/N-doped carbon nanorod was developed and immobilized on the sensing carbon electrode while cell culture solution filled the exposed fiber paper, allowing living cells to grow on the fiber paper surrounding the electrode. Due to the significantly shortening diffusion distance to access the sensing sites by such a unique device and a rationally tuned ratio of Fe2+/Mn2+, the device exhibits a fast response time (0.2 s), a low detection limit (0.4 μM), and a wide detection range (2-3200 μM). This work offers great promise for a low-cost and highly sensitive POCT device for practical clinic diagnosis and broad POCT biomedical applications.

Wearable electrochemical glucose sensor of high flexibility and sensitivity using novel mushroom-like gold nanowires decorated bendable stainless steel wire sieve

Long-term high blood glucose levels brings extremely detrimental effect on diabetic patients, such as blindness, renal failure, and cardiovascular diseases. Therefore, there is an urgent need to develop highly flexible and sensitive sensors for precisely non-invasive and continuous monitoring glucose levels. Herein, we present a highly flexible and sensitive wearable sensor for non-enzymatic electrochemical glucose analysis with vertically aligned mushroom-like gold nanowires (v-AuNWs) chemically grown on stainless steel wire sieve (SSWS) as integrated electrode. Owing to the unique nanostructures and excellent catalysis of the v-AuNWs, the as-fabricated glucose sensors exhibit superior flexibility and excellent electro-catalytic capability. In detail, these sensors display rapid response towards glucose within 5 s, and the sensor constructed with v-AuNWs for growth time of 15 min shows the highest sensitivity of 180.1 μA mM-1 cm-2 within a wide linear range of 6.5 × 10-4 mM-12.0 mM and the lowest detection limit of 0.65 μM (S/N = 3). It is noteworthy that due to the good ductility of the v-AuNWs and their strong contact with the SSWS substrate, these glucose sensors exhibit no obvious response variation after repeated bending for 100 times at bending angle of 180°. Additionally, the glucose sensors display superior anti-interfering capability as well as desirable repeatability. More importantly, these glucose sensors can be attached on human skin to determine sweat glucose reliably and analyze glucose concentration in human serum in vitro.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3',5,5,'-tetramethylbenzidine (TMB) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10-8 mol/L for o-aminophenol and 3.25 × 10-8 mol/L for m-aminophenol) and satisfactory recoveries (96.6-103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

An anti-fouling wearable molecular imprinting sensor based on semi-interpenetrating network hydrogel for the detection of tryptophan in sweat

The challenge of heavy biofouling in complex sweat environments limits the potential of electrochemical sweat sensors for noninvasive physiological assessment. In this study, a novel semi-interpenetrating hydrogel of PSBMA/PEDOT:PSS was engineered by interlacing PEDOT:PSS conductive polymer with zwitterionic PSBMA network. This versatile hydrogel served as the foundation for developing an anti-fouling wearable molecular imprinting sensor capable of sensitive and robust detection of tryptophan (Trp) in complex sweat. The incorporation of PEDOT:PSS conductive polymer into the semi-interpenetrating hydrogel introduced diverse physical crosslinks, including hydrogen bonding, electrostatic interactions, and chain entanglement. This incorporation considerably boosted the hydrogel's mechanical robustness and imparted commendable self-healing property. At the same time, the synergistic coupling between the well-balanced charge of the zwitterionic network and the high conductivity of the PEDOT:PSS polymer facilitated efficient charge transfer. The formation of the desired molecular imprinting membrane of semi-interpenetrating hydrogel was triggered by self-polymerization of dopamine (DA) in the presence of Trp. The designed biosensor demonstrated good sensitivity, selectivity and stability in detecting the target Trp. Notably, it also exhibited exceptional anti-fouling abilities, allowing for accurate Trp detection in complex real sweat samples, yielding results comparable to commercial enzyme-linked immunoassay (ELISA).

Advanced Silk Fibroin Biomaterials-Based Microneedles for Healthcare

Microneedles are a promising transdermal drug delivery system that has the advantages of minimal invasiveness, painlessness, and on-demand drug delivery compared with commonly used medical techniques. Natural resources are developed as next-generation materials for microneedles with varying degrees of success. Among them, silk fibroin is a natural polymer obtained from silkworms with good biocompatibility, high hardness, and controllable biodegradability. These properties provide many opportunities for integrating silk fibroin with implantable microneedle systems. In this review, the research progress of silk fibroin microneedles in recent years is summarized, including their materials, processing technology, detection, drug release methods, and applications. Besides, the research and development of silk fibroin in a multidimensional way are analyzed. Finally, it is expected that silk fibroin microneedles will have excellent development prospects in various fields.

Iodide-Mediated Etching of Gold Nanostar for the Multicolor Visual Detection of Hydrogen Peroxide

A multicolor visual method for the detection of hydrogen peroxide (H₂O₂) was reported based on the iodide-mediated surface etching of gold nanostar (AuNS). First, AuNS was prepared by a seed-mediated method in a HEPES buffer. AuNS shows two different LSPR absorbance bands at 736 nm and 550 nm, respectively. Multicolor was generated by iodide-mediated surface etching of AuNS in the presence of H₂O₂. Under the optimized conditions, the absorption peak Δλ had a good linear relationship with the concentration of H₂O₂ with a linear range from 0.67~66.67 μmol L^-1, and the detection limit is 0.44 μmol L^-1. It can be used to detect residual H₂O₂ in tap water samples. This method offered a promising visual method for point-of-care testing of H₂O₂-related biomarkers.