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Electrospun nanofibrous membranes have garnered significant attention in antimicrobial applications, owing to their intricate three-dimensional network that confers an interconnected porous structure, high specific surface area, and tunable physicochemical properties, as well as their notable capacity for loading and sustained release of antimicrobial agents. Tailoring polymer or hybrid-based nanofibrous membranes with stimuli-responsive characteristics further enhances their versatility, enabling them to exhibit broad-spectrum or specific activity against diverse microorganisms. In this review, we elucidate the pivotal advancements achieved in the realm of stimuli-responsive antimicrobial electrospun nanofibers operating by light, temperature, pH, humidity, and electric field, among others. We provide a concise introduction to the strategies employed to design smart electrospun nanofibers with antimicrobial properties. The core section of our review spotlights recent progress in electrospun nanofiber-based systems triggered by single- and multi-stimuli. Within each stimulus category, we explore recent examples of nanofibers based on different polymers and antimicrobial agents. Finally, we delve into the constraints and future directions of stimuli-responsive nanofibrous materials, paving the way for their wider application spectrum and catalyzing progress toward industrial utilization.

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Nanomaterial-based wound dressings have been extensively studied for the treatment of both minor and life-threatening tissue injuries. These wound dressings must possess several crucial characteristics, such as tissue compatibility, non-toxicity, appropriate biodegradability to facilitate wound healing, effective antibacterial activity to prevent infection, and adequate physical and mechanical strength to withstand repetitive dynamic forces that could potentially disrupt the healing process. Nevertheless, the development of nanostructured wound dressings that incorporate various functional micro- and nanomaterials in distinct architectures, each serving specific purposes, presents significant challenges. In this study, we successfully developed a novel multifunctional wound dressing based on poly(lactic acid) (PLA) fibrous membranes produced by solution-blow spinning (SBS) and electrospinning. The PLA-based membranes underwent surface modifications aimed at tailoring their properties for utilization as effective wound dressing platforms. Initially, beta-chitin whiskers were deposited onto the membrane surface through filtration, imparting hydrophilic character. Afterward, silver nanoparticles (AgNPs) were incorporated onto the beta-chitin layer using a spray deposition method, resulting in platforms with antimicrobial properties against both Staphylococcus aureus and Escherichia coli. Cytotoxicity studies demonstrated the biocompatibility of the membranes with the neonatal human dermal fibroblast (HDFn) cell line. Moreover, bilayer membranes exhibited a high surface area and porosity (> 80%), remarkable stability in aqueous media, and favorable mechanical properties, making them promising candidates for application as multifunctional wound dressings.

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In this study, poly(ε-caprolactone) (PCL)/gelatin (GEL) electrospun nanofibers loaded with two different concentrations of Pinus radiata bark extracts (PEs) were fabricated via electrospinning for wound healing applications. The effects of incorporating PE into PCL/GEL electrospun nanofibers were investigated regarding their physicochemical properties and in vitro biocompatibility. All electrospun nanofibers showed smooth, uniform, and bead-free surfaces. Their functional groups were detected by ATR-FTIR spectroscopy, and their total phenol content was measured by a Folin-Ciocalteu assay. With PE addition, the electrospun nanofibers exhibited an increase in their wettability and degradation rates over time and a decrease in their tensile stress values from 20 ± 4 to 8 ± 2 MPa for PCL/GEL and PCL/GEL/0.36%PE samples, respectively. PE was also released from the fibrous mats in a rather controlled fashion. The PCL/GEL/0.18%PE and PCL/GEL/0.36%PE electrospun nanofibers inhibited bacterial activity at around 6 ± 0.1% and 23 ± 0.3% against E. coli and 14 ± 0.1% and 18 ± 0.2% against S. aureus after 24 h incubation, respectively. In vitro cell studies showed that PE-loaded electrospun nanofibers enhanced HaCaT cell growth, attachment, and proliferation, favoring cell migration towards the scratch area in the wound healing assay and allowing a complete wound closure after 72 h treatment. These findings suggested that PE-loaded electrospun nanofibers are promising materials for antibiotic-free dressings for wound healing applications.

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Zika virus (ZIKV) infection is associated with the Guillain-Barré syndrome, and when non-vector congenital transmission occurs, fetal brain abnormalities are expected. After ZIKV infection, the blood, breast milk, and other body fluids contain low viral loads. Their detection is challenging as it requires the processing of larger input volumes of the clinical samples. Pre-enrichment is a valuable strategy to increase the analyte concentration. Therefore, the authors propose the use of a hierarchal composite polyaniline-(electrospun nanofiber) hydrogel mat (ENM) for the simultaneous enrichment and impedimetric sensing of ZIKV viral particles. The electrospinning conditions of polyvinyl alcohol and alginate, including blend formulation, were optimized through a factorial design. Disintegration and gelatinization were controlled via cross-linking to improve the hydrogel properties. Hierarchization was achieved by in situ chemical deposition of conductive polyaniline. The carboxyl groups of the ENM were used for the covalent immobilization of anti-ZIKV polyclonal antibodies used in the specific recognition of ZIKV within the medium of Vero cell culture. The specific capture and desorption of virions were studied at different pHs. ENMs were characterized by scanning electron microscopy and FTIR. Atomic force microscopy along with UV-vis and electrochemical impedance spectroscopies was used to monitor the antibody immobilization, ZIKV capture, and elution processes. Our results show that 14.2 mg (0.25 cm3) of ENM can capture 38.7 ± 2.5 µg of ZIKV with a desorption rate of 99.97% (38.29 ± 2.7 µg ZIKV), which is reusable for at least three times. Therefore, the capture capacity (micrograms of ZIKV captured per milligram of ENM) of polyaniline-hierarchized mats was 2.72 µg ZIKV/mg. The impedance LOD value was determined to be 2.76 µg of ZIKV particles (approximately 6.6 × 103 PFU/mL). As a result, we present a fast small-scale purification system that can simultaneously monitor ZIKV electrochemically and optically.

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The aim of this work was to study the biophysical properties of the chitosan-grafted poly(lactic acid) (CH-g-PLA) nanofibers loaded with silver nanoparticles (AgNPs) and chondroitin-4-sulfate (C4S). The electrospun CH-g-PLA:AgNP:C4S nanofibers were manufactured using the electrospinning technique. The microstructure of the CH-g-PLA:AgNP:C4S nanofibers was investigated by proton nuclear magnetic resonance (1H-NMR), scanning electron microscopy (SEM), UV-Visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and Fourier transform infrared (ATR-FTIR) spectroscopy. ATR-FTIR and 1H-NMR confirm the CH grafting successfully by PLA with a substitution degree of 33.4%. The SEM measurement results indicated apparently smooth nanofibers having a diameter range of 340 ± 18 nm with porosity of 89 ± 3.08% and an average pore area of 0.27 µm2. UV-Vis and XRD suggest that silver nanoparticles with the size distribution of 30 nm were successfully incorporated into the electrospun nanofibers. The water contact angle of 12.8 ± 2.7° reveals the hydrophilic nature of the CH-g-PLA:AgNP:C4S nanofibers has been improved by C4S. The electrospun CH-g-PLA:AgNP:C4S nanofibers are found to release ions Ag+ at a concentration level capable of rendering an antimicrobial efficacy. Gram-positive bacteria (S.aureus) were more sensitive to CH-g-PLA:AgNP:C4S than Gram-negative bacteria (E. coli). The electrospun CH-g-PLA:AgNP:C4S nanofibers exhibited no cytotoxicity to the L-929 fibroblast cells, suggesting cytocompatibility. Fluorescence microscopy demonstrated that C4S promotes the adhesion and proliferation of fibroblast cells onto electrospun CH-g-PLA:AgNP:C4S nanofibers.

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The use of ultraviolet (UV) and blue irradiation to sterilize surfaces is well established, but commercial applications would be enhanced if the light source is replaced with ambient light. In this paper, it is shown that nanofibers can be explored as an alternative methodology to UV and blue irradiation for bacterial inactivation. It is demonstrated that this is indeed possible using spun nanofibers of poly[lactic-co-(glycolic acid)] (PLGA). This work shows that PLGA spun scaffolds can promote photoinactivation of Staphylococcus aureus and Escherichia coli bacteria with ambient light or with laser irradiation at 630 nm. With the optimized scaffold composition of PLGA85:15 nanofibers, the minimum intensity required to kill the bacteria is much lower than in antimicrobial blue light applications. The enhanced effect introduced by PLGA scaffolds is due to their nanofiber structures since PLGA spun nanofibers were able to inactivate both S. aureus and E. coli bacteria, but cast films had no effect. These findings pave the way for an entirely different method to sterilize surfaces, which is less costly and environmentally friendly than current procedures. In addition, the scaffolds could also be used in cancer treatment with fewer side effects since photosensitizers are not required.

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Paper-based analytical devices (PADs) and Electrospun Fiber-Based Biosensors (EFBs) have aroused the interest of the academy and industry due to their affordability, sensitivity, ease of use, robustness, being equipment-free, and deliverability to end-users. These features make them suitable to face the need for point-of-care (POC) diagnostics, monitoring, environmental, and quality food control applications. Our work introduces new and experienced researchers in the field to a practical guide for fibrous-based biosensors fabrication with insight into the chemical and physical interaction of fibrous materials with a wide variety of materials for functionalization and biofunctionalization purposes. This research also allows readers to compare classical and novel materials, fabrication techniques, immobilization methods, signal transduction, and readout. Moreover, the examined classical and alternative mathematical models provide a powerful tool for bioanalytical device designing for the multiple steps required in biosensing platforms. Finally, we aimed this research to comprise the current state of PADs and EFBs research and their future direction to offer the reader a full insight on this topic.

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Biosensors are measurement devices that can sense several biomolecules, and are widely used for the detection of relevant clinical pathogens such as bacteria and viruses, showing outstanding results. Because of the latent existing risk of facing another pandemic like the one we are living through due to COVID-19, researchers are constantly looking forward to developing new technologies for diagnosis and treatment of infections caused by different bacteria and viruses. Regarding that, nanotechnology has improved biosensors' design and performance through the development of materials and nanoparticles that enhance their affinity, selectivity, and efficacy in detecting these pathogens, such as employing nanoparticles, graphene quantum dots, and electrospun nanofibers. Therefore, this work aims to present a comprehensive review that exposes how biosensors work in terms of bacterial and viral detection, and the nanotechnological features that are contributing to achieving a faster yet still efficient COVID-19 diagnosis at the point-of-care.

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In recent decades, there has been an increase in the research for the development and improvement of dye sensitized solar cells (DSSCs), owing to their singular advantages such as greater efficiency in energy conversion and overall performance in adverse environmental conditions. Therefore, work is carried out to enhance the energy efficiency of the components of the DSSCs: photoanode, counter-electrode, electrolyte, and dye sensitizer layer. Electrospun nanofibers in particular, have showed to be a novel alternative as components in DSSCs, mainly for energy conversion and as collector materials due in part to their tridimensional structure, high contact surface area and conductivity. Moreover, the incorporation of metallic compounds into nanofibers is advantageously employed in the electrospinning technique, owing to their conductivity and optical properties. Therefore, the present work consists of a detailed recompilation of the use of electrospun nanofibers loaded with metallic compounds and their application in DSSCs. The functionality of the components of DSSCs, parameters and experimental conditions of electrospinning, such as the intrinsic aspects in the polymer solution, are discussed and applied to the photoanode, counter-electrode and electrolyte of the DSSC. Lastly, the use of the electrospinning technique in combination with the use of metallic compounds could provide a great approach for the developing of DSSCs, with superior efficiency, high stability and durability.

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In recent years, electrochemical energy devices, i.e. batteries, fuel cells, solar cells, and supercapacitors, have attracted considerable attention of scientific community. The architecture of active materials plays a crucial role for improving supercapacitors performance. Herein, titanium dioxide (TiO2) nanofibers (1D) have been synthesized by electrospinning process and used as a backbone to manganese dioxide (MnO2) nanosheets (2D) growth through hydrothermal method. This strategy allows the obtaining of 1D/2D heterostructure architecture, which has demonstrated superior electrochemical performance in relation to pristine MnO2. The highest electrochemical performance is due to the synergic effect between the metal oxides, where TiO2 nanofibers provide electrochemical stability for active MnO2 phase. Thus, the designed TiO2@MnO2 structure can reach maximum specific capacitance of 525 F·g-1 at a current density of 0.25 A·g-1, and it demonstrates an excellent stability by retaining 81% of the initial capacitance with coulombic efficiency of 91%. Therefore, the novel architecture of TiO2@MnO2 based on nanofibers and nanosheets exhibits superior electrochemical properties to be used in supercapacitor applications.