Nanomaterial-functionalized electrospun scaffolds for tissue engineering.

Tissue engineering has emerged as a biological alternative aimed at sustaining, rehabilitating, or enhancing the functionality of tissues that have experienced partial or complete loss of their operational capabilities. The distinctive characteristics of electrospun nanofibrous structures, such as their elevated surface-area-to-volume ratio, specific pore sizes, and fine fiber diameters, make them suitable as effective scaffolds in tissue engineering, capable of mimicking the functions of the targeted tissue. However, electrospun nanofibers, whether derived from natural or synthetic polymers or their combinations, often fall short of replicating the multifunctional attributes of the extracellular matrix (ECM). To address this, nanomaterials (NMs) are integrated into the electrospun polymeric matrix through various functionalization techniques to enhance their multifunctional properties. Incorporation of NMs into electrospun nanofibrous scaffolds imparts unique features, including a high surface area, superior mechanical properties, compositional variety, structural adaptability, exceptional porosity, and enhanced capabilities for promoting cell migration and proliferation. This review provides a comprehensive overview of the various types of NMs, the methodologies used for their integration into electrospun nanofibrous scaffolds, and the recent advancements in NM-functionalized electrospun nanofibrous scaffolds aimed at regenerating bone, cardiac, cartilage, nerve, and vascular tissues. Moreover, the main challenges, limitations, and prospects in electrospun nanofibrous scaffolds are elaborated.

Cellulose nanofibers of oil palm fronds as a filler in nanocomposite coating for corrosion protection of copper.

Cellulose nanofibers (CNF) create a physical barrier preventing contact with corrosive substances and improving corrosion prevention. Oil palm fronds (OPF), the primary source of underused biomass waste from plantations, were processed into CNF. The OPF-CNF, mixed with hydroxyethyl cellulose as the matrix, forms a nanocomposite. Corrosion analysis using electrochemical methods demonstrated that copper coated with cellulose-rich nanocomposite containing 5 % CNF had a significantly decreased corrosion rate with an efficiency of 97.92 %. This CNF-based coating, combining barrier and passivation mechanisms, enhances performance, providing a competitive, eco-friendly alternative to conventional coatings.

Adsorptive removal of organophosphate pesticides from aqueous solution using electrospun carbon nanofibers.

Organophosphate pesticides (OPPs) are widely prevalent in the environment primarily due to their low cost and extensive use in agricultural lands. However, it is estimated that only about 5% of these applied pesticides reach their intended target organisms. The remaining 95% residue linger in the environment as contaminants, posing significant ecological and health risks. This underscores the need for materials capable of effectively removing, recovering, and recycling these contaminants through adsorption processes. In this research, adsorbent materials composed of electro-spun carbon nanofibers (ECNFs) derived from polyacrylonitrile was developed. The materials were characterized through several techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) analysis, and contact angle measurements. SEM analysis revealed details of the structural properties and inter-fiber spacing variations of the carbon nanofibers. The results revealed that ECNFs possess remarkable uniformity, active surface areas, and high efficiency for adsorption processes. The adsorption studies were conducted using batch experiments with ethion pesticide in aqueous solution. High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) was utilized to quantify the concentrations of the OPP. Various parameters, including adsorbent dosage, pH, contact time, and initial ethion concentration, were investigated to understand their impact on the adsorption process. The adsorption isotherm was best described by the Freundlich model, while the kinetics of adsorption followed a non-integer-order kinetics model. The adsorption capacity of the ECNFs for OPP removal highlights a significant advancement in materials designed for environmental remediation applications. This study demonstrates the potential of ECNFs to serve as effective adsorbents, contributing to the mitigation of pesticide contamination in agricultural environments.

W18O49 Nanofibers Functionalized with Graphene as a Selective Sensing of NO2 Gas at Room Temperature.

Recent trends in two-dimensional (2D) graphene have demonstrated significant potential for gas-sensing applications with significantly enhanced sensitivity even at room temperature. Herein, this study presents fabrication of distinctive gas sensor based on one-dimensional (1D) W18O49 nanofibers decorated 2D graphene, specifically coated on copper (Cu)-based interdigitated electrodes formed by DC sputtering, which can selectively detect NO2 gas at room temperature. The sensor device fabricated using W18O49/Gr1.5% (i.e., W18O49 nanofibers hybrid nanocomposite with 1.5 wt % graphene) displays excellent overall sensing performance at 27 °C (room temperature) with high response (∼150-160 times) to NO2 gas. The W18O49/Gr1.5%-based sensor device reflects the highly selective detection toward NO2 gas among various gases with quick response time of 3 s and speedy recovery in 6 s. The limit of detection of ∼0.3 ppm with excellent reproducibility and stability for 3 months in all weather conditions (tested in humidity conditions 20-97%) are superior features of the device under test. However, W18O49/Gr3% displayed higher selectivity for NO2 but resulted with comparatively reduced sensitivity than W18O49/Gr1.5% sensor. The enhanced sensing performance could be attributed to the graphene content to decorate the nanofibers on it, oxygen vacancies/defects, and the contacts between the sensing material and Cu. This favorable synthesis and properties of self-assembled hybrid composite materials provide a potential utilization for detecting NO2 gas in environmental safety inspection.

P(MMA-co-MAA)/cellulose nanofibers composites: Effect of hydrogen bonds on molecular mobility.

Cellulose nanofibers (CNFs) nanocomposites were prepared using poly(methylmethacrylate-co-methacrylic acid) (PMMA-co-MAA) to investigate the macromolecular mobility within the composite, with particular focus on the effect of H-bonding. Dynamic mechanical analysis (DMA) and broadband dielectric spectroscopy (BDS) were used to fully characterize the molecular mobility for which the effect of the introduction of H-bond forming moieties and the addition of CNFs (5 and 15 wt%) were assessed. Despite similar Tg values (determined by Differential Scanning Calorimetry), a deeper analysis of the relaxation times associated with the α-relaxation evidenced a significant effect induced by CNFs, which is in fact slowing down the macromolecular relaxation processes. The activation energy of the ß-relaxation remained unchanged despite the introduction of MAA units in the main chain and the successive addition of CNFs. However, the latter led to the appearance at low frequencies of a new ß'-relaxation correlated with the interactions between the CNF surface -OH groups and the -COOH groups of the matrix. The γ-relaxation showed a 45 % increase in activation energy from PMMA to PMMA-co-MAA + CNF nanocomposites regardless of the CNF content, due to the possibility of CNFs to interact and hinder the motion of the main chain methyl groups in α position.

Nanofiber-boosted retrograded starch/pectin microparticles for targeted 5-Aminosalicylic acid delivery in inflammatory bowel disease: In vitro and in vivo non-toxicity evaluation.

Incorporating 5-aminosalicylic acid (5-ASA) into a colon-specific carrier is crucial for treating inflammatory bowel diseases (IBD), as it enhances therapeutic efficacy, targets the affected regions directly, and minimizes side effects. This study evaluated the impact of incorporating cellulose nanofibers (CNF) on the in vitro and in vivo biological performance of retrograded starch/pectin (RS/P) microparticles (MPs) containing 5-ASA. Using Fourier Transform Infrared (FTIR) Spectroscopy, shifts in the spectra of retrograded samples containing CNF were observed with increasing CNF proportions, suggesting the establishment of new supramolecular interactions. Liquid absorption exhibited pH-dependent behaviors, with reduced absorption in simulated gastric fluid (∼269 %) and increased absorption in simulated colonic fluid (∼662 %). Increasing CNF concentrations enhanced mucoadhesion in porcine colonic sections, with a maximum force of 3.4 N at 50 % CNF. Caco-2 cell viability tests showed biocompatibility across all tested concentrations (0.0625-2.0000 mg/mL). Evaluation of intestinal permeability in Caco-2 cell monolayers demonstrated up to a tenfold increase in 5-ASA permeation, ranging from 29 % to 48 %. An in vivo study using Galleria mellonella larvae, with inflammation induced by LPS, showed reduction of inflammation. Given the scalability of spray-drying, these findings suggest the potential of CNF-incorporated RS/P microparticles for targeted 5-ASA delivery in IBD.

Solid-state Ru(bpy)32+ electrochemiluminescence sensor for trace detection of fenpropathrin using loofah sponge-like carbon nanofibers and CdS.

Loofah sponge-like carbon nanofibers (LF-Co,N/CNFs) were utilized as a carrier for Ru(bpy)32+, and then combined with CdS to create a novel solid-state electrochemiluminescence sensor capable of detecting trace amounts of fenpropathrin. LF-Co,N/CNFs, obtained through the high-temperature pyrolysis of ZIF-67 coaxial electrospinning fibers, were characterized by a loofah-like morphology and exhibited a significant specific surface area and porosity. Apart from serving as a carrier, LF-Co,N/CNFs also functioned as a luminescence accelerator, enhancing the system's luminescence efficiency by facilitating electron transmission and reducing the transmission distance. The inclusion of CdS in the luminescence reaction, in conjunction with Ru(bpy)32+, further boosted the sensor's luminescence signal. The resulting sensor demonstrated a satisfactory signal, with fenpropathrin causing significant quenching of the ECL signal. Under optimized conditions, a linear relationship between the signal quench value and fenpropathrin concentration in the range 1 × 10-12 to 1 × 10-6 M was observed, with a detection limit of 3.3 × 10-13 M (S/N = 3). This developed sensor is characterized by its simplicity, sensitivity, and successful application in detecting fenpropathrin in real samples. The study not only presents a straightforward detection platform for fenpropathrin but also introduces new avenues for the rapid determination of various food contaminants, thereby expanding the utility of carbon fibers in electrochemiluminescence sensors.

Modulating the isotopic hydrogen-deuterium exchange in functionalized nanocellulose to optimize SANS contrast.

Contrast matching by isotopic exchange in cellulose allows visualizing functional groups, biomolecules, polymers and nanoparticles embedded in cellulosic composites. This isotopic exchange varies the scattering length density of cellulose to match its contrast with the background network. Here, contrast matching of microcrystalline-cellulose (MCC) and the functionalized nanocellulose-fiber (CNF) and cellulose nanocrystals (CNC) are elucidated by small angle neutron scattering (SANS). Results show no isotopic exchange occurs for the CNF surface functionalized with carboxyl nor for the CNC-High with a high sulfate groups concentration. Both CNC-Low, with low sulfate groups, and MCC exchange 1H with 1D in D2O. This is due to the high exchange probability of the labile C6 position primary -OH group. The structure of thermo-responsive poly-N-isopropylacrylamide (PNIPAM) chains grafted onto CNF (PNIPAM-grafted-CNF) was extracted by CNF contrast matching near the lower critical solution temperature. Contrast matching eradicates the CNF scattering to retain only the scattering from the grafted-PNIPAM chains. The coil to globule thermo-transition of PNIPAM was revealed by the power law variation from q-1.3 to q-4 in SANS. Isotopic exchange in functionalized cellulosic materials reveals the nano- and micro-scale structure of its individual components. This improved visualization by contrast matching can be extended to carbohydrate polymers to engineer biopharmaceutical and food applications.

Fabrication of a green double-layered hybrid nanocomposite via electrospinning of polyethersulphone/natural deep eutectic solvent on bacterial cellulose for determination of multiclass pesticides in water samples.

A novel nanofibrous double-layered biosorbent was fabricated by electrospinning polyethersulfone (PES) doped with a natural deep eutectic solvent (DES), composed of choline chloride (ChCl) and caffeic acid (CFA) in a 3:1 molar ratio, onto a bacterial cellulose (BC) substrate. The pristine PES/DES@BC biosorbent was employed in a thin film-solid phase microextraction (TF-SPME) to extract 12 multiclass pesticides from water. Characterization techniques, including ATR-FTIR, FT-NMR, SEM, and nitrogen adsorption/desorption isotherms, confirmed the nanofibrous structure of the electrospun PES-DES and BC biopolymer. The method was validated for matrix effect, specificity, reproducibility, limits of quantification (0.03-0.10 µg/L), and enrichment factor (7-14). Matrix-match calibration linearity ranged from 0.03 to 500 µg/L, with determination coefficients (r²) between 0.9884 and 0.9994. Intra-day and inter-day relative standard deviations (RSDs) were 1.2-3.6 % and 7.0-9.3 %, respectively. The composition of the biosorbent and the fabrication reproducibility across different batches were also thoroughly examined. The accuracy was evaluated by measuring extraction recoveries in six environmental water samples, which ranged from 75 to 105 % (RSDs < 9.0 %). Furthermore, the sustainability of the method was evaluated with the Analytical Eco-Scale and Analytical Greenness metrics. To our knowledge, this study represents the first synthesis and combination of [ChCl:[CFA] DES with PES to create a double-layered nanofiber biosorbent, as well as its application for extracting various pesticide groups from water samples.

Nanofiber-Based Drug Delivery Systems: A Review on Its Applications, Challenges, and Envisioning Future Perspectives.

Nanomaterials, especially nanofibers, hold considerable promise as drug delivery systems (DDS) by providing targeted administration of drugs due to their unique properties, such as large surface area, high porosity, and mechanical robustness. Nanofibers can be fabricated using various techniques like electrospinning, self-assembly, phase separation, and template synthesis, offering properties such as adjustable size, shape, high precision, and biodegradability. Additionally, features such as multiple target functionalization, controlled release of the drug, and prolonged circulation of the drug make nanofibers particularly suitable for biomedical applications, including drug delivery, tissue regeneration, and biosensing. This comprehensive review explores the characteristics, types, fabrication methods, and applications of nanofibers. Diverse types of polymer nanofibers are used in drug delivery, such as blended nanofibers, core-shell nanofibers, and layer-by-layer assembly, each demonstrating their own advantages in controlled drug release and targeted therapy. Electrospun nanofibers are extensively utilized in biomedical applications due to their superior mechanical performance and high porosity and advancements in coaxial electrospinning enabling the fabrication of core-shell nanofibers, offering controlled drug release kinetics and protection of loaded molecules. These nanofibers demonstrate enhanced bioactivity and biocompatibility and can find application in tissue engineering. Furthermore, this review addresses the challenges associated with nanofiber production, including reproducibility and scalability. Nanofibers exhibit the potential to revolutionize medical treatment across diverse therapeutic areas. Future research directions and challenges in nanofiber-based drug delivery discussed in this review offer guidance for further advancements in this rapidly evolving field.

Advances in Mussel Adhesion Proteins and Mussel-Inspired Material Electrospun Nanofibers for Their Application in Wound Repair.

Mussel refers to a marine organism with strong adhesive properties, and it secretes mussel adhesion protein (MAP). The most vital feature of MAP is the abundance of the 3,4-dihydroxyphenylalanine (DOPA) group and lysine, which have antimicrobial, anti-inflammatory, antioxidant, and cell adhesion-promoting properties and can accelerate wound healing. Polydopamine (PDA) is currently the most widely used mussel-inspired material characterized by good adhesion, biocompatibility, and biodegradability. It can mediate various interactions to form functional coatings on cell-material surfaces. Nanofibers based on MAP and mussel-inspired materials have been exerting a vital role in wound repair, while there is no comprehensive review presenting them. This Review introduces the structure of MAPs and their adhesion mechanisms and mussel-inspired materials. Second, it introduces the functionalized modification of MAPs and their inspired materials in electrospun nanofibers and application in wound repair. Finally, the future development direction and coping strategies of MAP and mussel-inspired materials are discussed. Moreover, this Review can offer novel strategies for the application of nanofibers in wound repair and bring about new breakthroughs and innovations in tissue engineering and regenerative medicine.

Unique Core-Shell Structured Polyaniline Nanofibers Toward Ultrahigh-Rate Flexible All-Solid-State Supercapacitor.

Promoting charge storage and fast charging capability simultaneously is a long-standing challenge for supercapacitors. A facile flowing seed polymerization is adopted to prepare polyaniline (PANI) nanofibers, in which phytic acid (PA) doped oligomers are first produced as the seeds for promoting the highly oriented growth of PANI nanofibers accompanying with the copolymerization of m-aminobenzene sulfonic acid (ASA) and aniline occurred on the surface of PANI nanofibers, as a result, unique core-shell structured PANI nanofibers are continuously fabricated. Benefitting from compact nanofiber structure, excellent dispersion, and self-doping effect, as-prepared PANI nanofibers exhibit a specific capacitance of 671.2 F g-1 at 2 A g-1 and ultrahigh rate capability of 93.1% from 2 to 100 A g-1. Then assembled all-solid-state supercapacitor can deliver the highest energy density of 28.3 Wh kg-1 at a power density of 320.2 W kg-1 with remarkable rate capability (81.2% from 1 to 20 A g-1), cycle stability (77.5% after 5000 cycles) as well as light weight and flexibility. It is highly desirable that the present green and scalable approach can be further applied to fabricate other unique core-shell structured PANI nanofibers with appealing potentials in energy storage devices.

Electrokinetic particle trapping in microfluidic wells using conductive nanofiber mats.

The frequency dependence of electrokinetic particle trapping using large-area (>mm2) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1 µm) were trapped at various electric field frequencies between 30 kHz and 1 MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the CNF mats was greater at all tested frequencies than that of the control of no applied field, and the greatest trapping was observed at a frequency of 600 kHz, where electrothermal flow is more significantly weakened than DEP. Theoretical analysis and measured impedance spectra indicate that this result was due to a combination of the frequency dependence of DEP and capacitive behavior of the well-based device.

Copper dual-doping strategy of porous carbon nanofibers and nickel fluoride nanorods as bi-functional oxygen electrocatalysis for effective zinc-air batteries.

Designing and developing efficient, low-cost bi-functional oxygen electrocatalysts is essential for effective zinc-air batteries. In this study, we propose a copper dual-doping strategy, which involves doping both porous carbon nanofibers (PCNFs) and nickel fluoride nanoparticles with copper alone, successfully preparing copper-doped nickel fluoride (NiF2) nanorods and copper nanoparticles co-modified PCNFs (Cu@NiF2/Cu-PCNFs) as an efficient bi-functional oxygen electrocatalyst. When copper is doped into the PCNFs in the form of metallic nanoparticles, the doped elemental copper can improve the electronic conductivity of composite materials to accelerate electron conduction. Meanwhile, the copper doping for NiF2 can significantly promote the transformation of nickel fluoride nanoparticles into nanorod structures, thus increasing the electrochemical active surface area and enhancing mass diffusion. The Cu-doped NiF2 nanorods also possess an optimized electronic structure, including a more negative d-band center, smaller bandgap width and lower reaction energy barrier. Under the synergistic effect of these advantages, the obtained Cu@NiF2/Cu-PCNFs exhibit outstanding bi-functional catalytic performances, with a low overpotential of 0.68 V and a peak power density of 222 mW cm-2 in zinc-air batteries (ZABs) and stable cycling for 800 h. This work proposes a one-step way based on the dual-doping strategy, providing important guidance for designing and developing efficient catalysts with well-designed architectures for high-performance ZABs.

Poly(3,4-Ethylenedioxythiophene):Sulfamic Acid Modified Aramid Nanofibers: An Innovative Conductive Polymer With Enhanced Electromagnetic Interference Shielding and Thermoelectric Performance.

The development of alternative conductive polymers for the well-known poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is of great significance for improving the stability in long-term using and high-temperature environments. Herein, an innovative PEDOT:S-ANF aqueous dispersion is successfully prepared by using sulfamic acid (SA) to modified aramid nanofibers (S-ANF) as an alternative dispersant for PSS and the subsequent in situ polymerization of PEDOT. Thanks to the excellent film forming ability and surface negative groups of S-ANF, the PEDOT:S-ANF films show comparable tensile strength and elongation to unmodified PEDOT:ANF. Meanwhile, PEDOT:S-ANF has a high conductivity of 27.87 S cm-1, which is more than 20 times higher than that of PEDOT:PSS. The film exhibits excellent electromagnetic interference (EMI) shielding and thermoelectric performance, with a shielding effectiveness (SE) of 31.14 dB and a power factor (PF) of 0.43 µW m-1K-2. As a substitute for PSS, S-ANF exhibits significant structural and physicochemical properties, resulting in excellent chemical and thermal stability. Even under harsh conditions such as immersing to 0.1 M HCl, 0.1 M NaOH, and 3.5% NaCl solution, or high temperature conditions, the PEDOT:S-ANF films still maintain exceptional EMI shielding performance. Therefore, this multifunctional conductive polymer exhibits enormous potential and even proves its reliability in extreme situations.

Polyvinyl alcohol-chitosan loaded oleanolic acid nanofibers against bacterial infection: In vitro studies and in-vivo evaluation by optical and laser Doppler imaging modalities.

The present work focuses on the fabrication of Polyvinyl alcohol-chitosan-loaded oleanolic acid-nanofibers (PVA-CS-OLA-NFs) for bacterial infection. The prepared PVA-CS-OLA-NFs were characterized for contact angle, SEM, AFM, XRD, FTIR, and TGA. The solid-state characterization and in vitro performance evaluation of nanofibers reveal consistent interconnection and diameters ranging from 102 ±â€¯9.5 to 386 ±â€¯11.6 nm. The nanofibers have a flat surface topography and exhibit efficient drug entrapment. Moreover, the in vitro release profile of PVA-CS-OLA-NFs was found to be 51.82 ±â€¯1.49 % at 24 h. Furthermore, the hemocompatibility study showed that the developed PVA-CS-OLA-NFs are non-hemolytic to human blood. The PVA-CS-OLA-NFs demonstrate remarkable antibacterial capabilities, as evidenced by their MBC and MIC values, which range from 128 and 32 µg/mL, against the strains of S. aureus. The in-vivo fluorescence optical imaging showed the sustained PVA-CS-OLA-NFs release at the wound site infected with S. aureus for a longer duration of time. Moreover, the PVA-CS-OLA-NFs showed superior wound healing performance against S. aureus infected wounds compared to the marketed formulation. Further, the laser Doppler imaging system improved oxygen saturation, blood supply, and wound healing by providing real-time blood flow and oxygen saturation information.

Supported liquid phase extraction using wetted nanofiber discs as a simple approach for in-vial extraction of chlorophenols and insecticides from river water prior to HPLC-DAD analysis.

BACKGROUND: A novel supported liquid extraction approach using small polymeric nanofibrous discs was demonstrated and applied to the analysis of real river water. Nanofibrous discs were tested to extract model mixture of 9 common water contaminants 4-nitrophenol, various chlorophenols, bisphenol A, permethrin, and fenoxycarb featuring a wide range of log P values (1.9-6.5). Polyacrylonitrile, polyhydroxybutyrate, and polylactic acid nanofibers were selected as adsorptive materials. One-step desorption was performed directly in HPLC vials, to avoid time-consuming evaporation and reconstitution steps. The discs were allowed to sediment to the bottom of the vial before injection into the chromatographic system. RESULTS: Various parameters affecting the extraction efficiency including 1-octanol volume, extraction time, ionic strength, and sample volume were investigated and optimized. Wetting the nanofiber discs with 1-octanol resulted in up to 20-fold increase in enrichment factor when compared to non-wetted polymer counterparts. The highest enrichment factors were observed for analytes with a log P range of 3.3-4.5. Our developed method showed good linearity in the range 20-200 µg/L for all analytes tested. Satisfactory repeatability with RSD <13 % were achieved covering all steps including disc preparation, wetting, extraction/elution, and chromatography analysis, and recoveries ranged from 58.93 to 121.43 %. SIGNIFICANCE: This work represents novel simple supported liquid extraction approach using impregnated polymer nanofiber discs. Using only 50 µL 1-octanol, we reduced the organic solvent compared to other extraction methods. There was no need for any plastic cartridge to hold the sorbent and direct in-vial desorption reduced the unnecessary, time-consuming steps and simplified the sample preparation protocol.

Template-assisted Flexible-to-rigid Transition of Peptides in Head-to-tail Self-polymerization Enables Sequence-controllable and Post-modifiable Peptide Nanofibers.

Peptide-based nanofibers are promising materials for many essential applications and can be generalized into two categories, self-assembling peptide nanofibers (SAPNs) and poly(amino acid) nanofibers (PAANs). Non-covalent SAPNs are sequence-controllable, but poorly stable and not suitable for post-modification. While covalent PAANs are post-modifiable, however, their sequences are either monotonic or undefined. The nanofibers obtained by head-to-tail covalent coupling polymerization of sequence-known peptides, which we call series-connected peptide nanofibers (SCPNs), promise to have the advantages of both SAPNs and PAANs, but they are barely reported. The undesired backbiting effect during the head-to-tail polymerization is one of the possible challenges. Here, we present a template-assisted strategy to trigger the flexible-to-rigid transition of peptide units, which can avoid the backbiting effect and enable consecutive intermolecular polymerization of peptides to produce desired sequence-controlled covalent SCPNs. SCPNs are highly stable and can function as excellent parent materials for various post-processing to create diverse hierarchical materials independent of the peptide sequence. Moreover, SCPNs allow for the display of predetermined functional groups at regular intervals along the nanofibers by pre-modification of the initial peptide sequence. SCPNs represent a new category of peptide-based nanofibers with outstanding performances and vast potential.

Electrospinning-based sensing technologies: Opportunities for food applications.

The article explores the science and practice of electrospinning, tracing its history and examining the factors that influence fiber morphology, including the solution composition, processing conditions, and environmental conditions. It offers a thorough examination of electrospinning fundamentals geared toward generating an appropriate platform for creating tailored nanofibers for sensing applications in the food industry. These nanofibers play a critical role in food analysis, sensing, and traceability, and we highlight their effectiveness in identifying pesticide residues, food components, antibiotics, heavy metals, and foodborne pathogens as well as in monitoring the freshness and spoilage of food. The use of electrospinning technology is poised to make sensing platforms more accessible, affordable, and widespread, thereby significantly contributing to the improvement of food quality and safety monitoring practices.

Sodium alginate supramolecular nanofibers in synergy with surface crack engineering to prepare tough and highly sensitive hydrogels.

Soft and wet hydrogels often struggle to achieve both toughness and high sensitivity simultaneously, limiting their usefulness in flexible devices. To tackle this challenge, we devised a strategy that combines supramolecular sodium alginate nanofibers, utilizing Zr4+ as physical crosslinkers, with surface crack engineering via the micro-phase separation of polyaniline, to create a physically and chemically dual crosslinked polyacrylamide (PAM)/sodium alginate (SA)/polyaniline (PANI) hydrogel with exceptional toughness and high sensitivity. Owing to the supramolecular sodium alginate nanofibers, the dual crosslinked hydrogel exhibited a tensile strength of 0.391 MPa, an elongation at break of 568.9 %, and a toughness of 1.020 MJ/m3. The in-situ polymerized polyaniline layer, confined within the dense network, introduced micro-cracks onto the hydrogel surface, resulting in a high gauge factor of 11.4 for the fabricated hydrogel. Furthermore, integrating this hydrogel into a triboelectric nanogenerator transformed it into self-powered sensors capable of detecting external forces and generating various signals without power supply. These findings suggest that the developed hydrogel held great potential in diverse fields, including human motion detection, human-machine interaction, and wearable electronic devices.