Under control: Controlled assemblies of gold nanorods in a poly(vinyl alcohol) (PVA) nanofiber matrix with tunable optical properties can be achieved by using electrospinning. The resultant assemblies can be used as substrates for surface-enhanced Raman spectroscopy (SERS). This work provides a facile way to control alignment of anisotropic nanostructures in a polymer nanofiber matrix and generates new assemblies with interesting properties.
Gold nanorods (AuNRs) can be successfully co-assembled with Ag nanowires (AgNWs) to form a kind of AuNR-AgNW nanocomposite by electrostatic attraction, in which the AuNRs are arranged along the long axial direction of the AgNWs with a preferential string-like alignment. The assembled AuNR-AgNW nanocomposites are then further embedded within polyvinyl alcohol (PVA) nanofibers by electrospinning, by which both AuNRs and AgNWs can be stabilized and arranged along the axis of polymer nanofibers. When the polymer nanofibers are aligned by collecting on a copper mesh with a woven structure, the AuNR-AgNW nanocomposites assembled within the electrospun nanofibers are also arranged. The influences of the AuNR-AgNW assemblies with different amounts of AuNRs attached on AgNWs on the optical properties and surface enhanced Raman scattering (SERS) enhancement have been investigated. The resulting AuNR-AgNW/PVA electrospun mats show red-shifted and broader absorption bands and higher SERS performances compared with the normal casting films with randomly dispersed AuNRs and AgNWs, or electrospun mats with monometallic components, due to the order alignment of AuNR-AgNW nanocomposites on a large scale.
1D nanomaterials have attracted explosive attention in the context of the physical and chemical fi elds, owing to their potential for novel applications in electronic and optical devices. [ 1 ] With the development of synthetic methodologies, 1D nanomaterials have achieved great success and a wide variety of different materials from organic polymers to inorganic compounds have been prepared. [ 2 , 3 ] Recently, research activities in the fi eld of nanoscience are shifting from the preparation of individual nanoparticles (NPs) to the preparation of NP assemblies and the realization of their applications. [ 4 ] From the viewpoint of application, assembly of these 1D nanomaterials into functional nanomaterials and devices is required, especially for alignment in large scale, which is still one of the most diffi cult problems hindering their applications.Various methods based on self-assembly or directed self-assembly techniques have been used to assemble nanomaterials into functional devices. Several reviews focused on assembly have also appeared. [4][5][6] However, most of these methods have been applied to assemble 1D nanostructures with low aspect ratios, such as NPs and nanorods (NRs); few techniques have been successfully applied to assemble nanowires (NWs) with high aspect ratios because the magnitude and range of the repulsive forces of wires, rods, and particles decrease in sequence. [ 7 ] The Langmuir-Blodgett (LB) technique provides a useful way to assemble NWs. [ 8 ] Recently, it has been reported that AgNWs can be spontaneously assembled at the oil-water-air interface to form ordered NW fi lms. [ 9 ] These two methods each have their own advantages, but the prepared samples are usually substratebased. New methods for NW self-assembly are still required to ensure effi cient scale-up of the fabrication, a high level of directed assembly, and a high level of control.Electrospinning is a facile method that enables the convenient fabrication of composite nanofi bers as a variety of functional components can be directly added into the solution for electrospinning, [ 10 ] such as NPs, NWs, and molecular species, [11][12][13] and the obtained nanofi bers have a wide range of compositions and well-defi ned functionalities. Several reports found that anisotropic nanostructures, such as carbon nanotubes (CNTs) [ 14 , 15 ] and calcium silicate hydrate (CSH), [ 16 ] were aligned along the axis of the polymer fi bers, and the mechanical properties of the electrospun mats were conseqeuntly enhanced. Recently, Ag-and AuNPs have been electrospun within polymer fi bers to prepare fl exible free-standing surface-enhanced Raman spectroscopy (SERS) substrates and AuNWs, respectively. [ 11 , 17 ] AuNRs have also been electrospun to investigate the assembly effect of electrospinning on 1D nanostructures with low aspect ratios, and the AuNR-AgNW nanocomposites were also successfully assembled within the polymer fi bers using electrospinning. [ 18 ] However, the electrospun fi bers are randomly dispersed, so the NRs embedded ...
The topical application of exosomes secreted by mesenchymal stem cells (MSC-Exos) on the skin is a very new and interesting topic in the medical field. In this study, we aimed to investigate whether marine sponge Haliclona sp. spicules (SHSs) could effectively enhance the skin delivery of human umbilical cord-derived MSC-Exos (hucMSC-Exos), and further evaluate the topical application of hucMSC-Exos combined with SHSs in rejuvenating photoaged mouse skin. Materials and Methods: SHSs were isolated from the explants of sponge Haliclona sp. with our proprietary method, and hucMSC-Exos were prepared from the conditioned medium of hucMSCs using ultracentrifugation. The effects of SHSs on the skin penetration of fluorescently labeled hucMSC-Exos were determined using confocal microscopy in vitro (porcine skin) and in vivo (mouse skin). The therapeutic effects of hucMSC-Exos coupled with SHSs against UV-induced photoaging in mice were assessed by using microwrinkles analysis, pathohistological examination and real-time RT-PCR. We also tested the skin irritation caused by the combination of hucMSC-Exos and SHSs in guinea pigs. Results: In vitro results showed that hucMSC-Exos could not readily penetrate through porcine skin by themselves. However, SHSs increased the skin absorption of exosomes by a factor of 5.87 through creating microchannels. Similar penetration enhancement of hucMSC-Exos was observed after SHSs treatment in mice. The combined use of hucMSC-Exos and SHSs showed significant anti-photoaging effects in mice, including reducing microwrinkles, alleviating histopathological changes, and promoting the expression of extracellular matrix constituents, whereas hucMSC-Exos alone produced considerably weaker effects. Skin irritation test showed that the combination of hucMSC-Exos and SHSs caused slight irritation, and the skin recovered shortly. Conclusion: SHSs provide a safe and effective way to enhance the skin delivery of MSC-Exos. Moreover, the combination of MSC-Exos and SHSs may be of much use in the treatment of photoaging.
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