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Graphical abstract Abstract In the present work, polypyrrole hollow fibers (PPy-HFs) were fabricated by sacrificial removal of soft templates of electrospun polycaprolactone (PCL) fibers with polypyrrole (PPy) coating through chemical polymerization of pyrrole monomer. Different physicochemical properties of as-fabricated PPy-HFs were then studied by Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectroscopy, Differential scanning calorimetry/Thermogravimetric analysis (DSC/TGA), and X-ray photoelectron spectroscopy (XPS). The photothermal activity of PPy-HF was studied by irradiating 808-nm near infra-red (NIR) light under different power values with various concentrations of PPy-HFs dispersed in phosphate buffer solution (PBS, pH 7.4). These PPy-HFs exhibited enhanced photothermal performance compared with polypyrrole nanoparticles (PPy-NPs). Furthermore, these PPy-HFs showed photothermal effect that was laser-power- and concentration-dependent. The photothermal toxicity of the resulting nanofiber was evaluated using cell counting kit-8 (CCK-8) and live and dead cell assays. Results showed that these PPy-HFs were more effective in killing cancer cells under NIR irradiation. In contrast, hollow-fiber showed no cytotoxicity without NIR exposure. Among different nanofiber formulations, PPy-160 exhibited the highest photothermal toxicity. It could be explained by its enhanced photothermal performance compared to other specimens. The resulting PPy-HFs showed superior drug-loading capacity to PPy-NPs. This might be attributed to adequate binding of the drug into both luminal and abluminal hollow-fiber surfaces. Fabrication of this substrate type opens a promising new avenue for architectural design of biocompatible organic polymer for biomedical field. [ABSTRACT FROM AUTHOR]

Mesoporous architectures are remarkable electrode materials for energy storage system due to their large number of active sites and high surface area. Here we report, mesoporous MoS 2 particles (pore diameter 34.04 nm) well attached to the surface of thin layered reduced graphene oxide (rGO) via an ultrasonic chemical method for supercapacitor applications. The rGO not only increases the conductivity of MoS 2 but also provides a substrate for the attachment of MoS 2 with low aggregation. The porous MoS 2 provides a large surface area and sufficient way for the fast transport of electrolyte ions toward electrode materials. As a result, the synthesized MoS 2 /rGO composites exhibited excellent electrochemical performance with a specific capacitance 314.5 F/g in 2M KOH aqueous solution at a scan rate of 10 mV/s and excellent specific capacitance retention (80.02%) after 1000 cycles in a three electrode system for energy storage applications. [ABSTRACT FROM AUTHOR]

Depositing of hierarchical ZnO nanostructures on electrospun nanofibers and their proper attachment has gained significant interest for myriad applications. However, the weak attachment of such nanostructures to the nanofiber surface limits their practical applications. In this study, a simple and efficient method has been developed for preparing hierarchical ZnO nanorod deposited polyurethane (PU) nanofiber by combining electrospinning, surface functionalization and hydrothermal treatment. Electrospun PU nanofibers were coated with polydopamine (Pdopa) via dip coating method. The resulting Pdopa coated PU nanofibrous mat was soaked in aqueous ZnO nanoparticles (ZnONPs) solution in order to seed the metal-oxide particles on its surface. Later, ZnO nanorods (ZNRs) were grown on the ZnO-seeded electrospun PU nanofiber via a hydrothermal process. X-ray photoelectron spectroscopy (XPS), Field-Emission Scanning electron microscopy (FE-SEM), X-ray diffraction pattern (XRD) and infra-red (IR) spectra indicated that ZnO nanorods firmly adhered to the functionalized PU nanofiber surface and had high photocatalytic/antimicrobial activity at the low-intensity UV-LED device with good reusability. The catechol group of Pdopa not only causes adhesion of ZnO nanostructures, but also act as an electron trap, preventing the recombination of e-h pairs and thereby improving the photocatalytic efficiency. We believe that the fabricated composite membrane with antifouling effect and photocatalytic activity is a potential candidate for organic pollutant degdration and wastewater purification. [ABSTRACT FROM AUTHOR]

A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3 μA mM −1 cm −2 , the linear range up to 4.7 mM (R 2 = 0.9992), and a low detection limit of 5 μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications. [ABSTRACT FROM AUTHOR]

We report for the first time a polycaprolactone–human serum albumin (PCL–HSA) membrane with bimodal structures comprised of spider-web-like nano-nets and conventional fibers via facile electro-spinning/netting (ESN) technique. Such unique controllable morphology was developed by electrospinning the blend solution of PCL (8 wt% in HFIP 1,1,1,3,3,3,-Hexafluoro-2-propanol) and HSA (10 wt% deionized water). The phase separation during electrospinning caused the formation of bimodal structure. Various processing factors such as applied voltage, feeding rate, and distance between nozzle tip and collector were found responsible for the formation and distribution of the nano-nets throughout the nanofibrous mesh. Field emission electron microscopy (FE-SEM) confirmed that the nano-nets were composed of interlinked nanowires with an ultrathin diameter (10–30 nm). When compared with a pure PCL membrane, the membrane containing nano-nets was shown to have better support for cellular activities as determined by cell viability and attachment assays. These results revealed that the blending of albumin, a hydrophilic biomolecule, with PCL, a hydrophobic polymer, proves to be an outstanding approach to developing membranes with controlled spider-web-like nano-nets for tissue engineering. [ABSTRACT FROM AUTHOR]

A simple and efficient approach is developed to immobilize TiO 2 nanofibers onto reduced graphene oxide (RGO) sheets. Here, TiO 2 nanofiber-intercalated RGO sheets are readily produced by two-step procedure involving the use of electrospinning process to fabricate TiO 2 precursor containing polymeric fibers on the surface of GO sheets, followed by simultaneous TiO 2 nanofibers formation and GO reduction by calcinations. GO sheets deposited on the collector during electrospinning/electrospray can act as substrate on to which TiO 2 precursor containing polymer nanofibers can be deposited which give TiO 2 NFs doped RGO sheets on calcinations. Formation of corrugated structure cavities of graphene sheets decorated with TiO 2 nanofibers on their surface demonstrates that our method constitutes an alternative top-down strategy toward fabricating verities of nanofiber-decorated graphene sheets. It was found that the synthesized TiO 2 /RGO composite revealed a remarkable increased in photocatalytic activity compared to pristine TiO 2 nanofibers. Therefore, engineering of TiO 2 nanofiber-intercalated RGO sheets using proposed facile technique can be considered a promising method for catalytic and other applications. [ABSTRACT FROM AUTHOR]

In this study, a fly ash based composite, Ag–iron oxide/fly ash, was synthesized via a facile one-pot hydrothermal process using fly ash, ferrous chloride, and silver nitrate as precursors. Field emission scanning electron microscopy (FE-SEM), EDX, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), Photoluminescence (PL) and Brunauer–Emmett–Teller (BET) surface area measurement confirmed the formation of composite particle. FA provided a suitable surface for the in-situ deposition of Fe 3 O 4 and Ag NPs during hydrothermal treatment. As a result, the particle size of Fe 3 O 4 and Ag NPs was sufficiently decreased, and the surface area of the NPs as well as, a whole matrix was increased. The antimicrobial activity of the composite was accessed by Escherichia coli inhibition assay. Lead(II) ion adsorption efficiency of the composite was analyzed from a series of batch adsorption experiments (the effects of concentration, contact time, pH and adsorbent dose on the adsorption of Pb(II) ion from aqueous solution). Results indicated that as-synthesized composite has high antibacterial capacity, and the metal ions uptake efficiency compared to fly ash particle. Furthermore, incorporation Fe 3 O 4 NPs onto the fly ash make it easily separable from a reaction system using an external magnet. The composite synthesis protocol is a simple method that utilizes a readily available industrial byproduct to produce a unique composite for environmental remediation. [ABSTRACT FROM AUTHOR]

This study was aimed on the eco-friendly synthesis of silver nanoparticles (AgNPs), reduced graphene oxide (rGO) and AgNPs decorated rGO (rGO/AgNPs) nanocomposite and appraisal of their bioactivities and toxicity. As-prepared nanomaterials were established through high resolution X-ray diffraction (HR-XRD), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV–Vis. spectroscopy and Fourier transform infrared spectroscopy (FT-IR). In this study, leaves extract, graphene oxide (GO) and rGO did not show antibacterial and anticancer activities; no significant embryo toxicity was recorded. On the other hand, AgNPs displayed good antibacterial and anticancer activities; however, higher toxic effects were observed even at the lowest test concentration (0.7 μg/ml). In case of rGO/AgNPs nanocomposite, significant antibacterial activity together with low cytotoxicity was noticed. Interestingly, the embryo toxicity of AgNPs was significantly reduced by rGO, implying the biocompatible nature of as-synthesized nanocomposite. Taken together, these results clearly suggest that rGO/AgNPs nano hybrid composite could be developed as the promising biomaterial for future biomedical applications. [Display omitted] • In this study, AgNPs, rGO and rGO/AgNPs composites were prepared. • AgNPs showed good antibacterial and anticancer activities. • However, higher toxicity was observed even at 0.7 μg/ml of AgNPs. • rGO/AgNPs displayed good antibacterial activity with low cytotoxicity. • Interestingly, the toxic effects of AgNPs were significantly reduced by rGO. [ABSTRACT FROM AUTHOR]