A novel label-free surface plasmon resonance (SPR) aptasensor has been constructed for the detection of N-gene of SARS-CoV-2 by using thiol-modified niobium carbide MXene quantum dots (Nb 2 C-SH QDs) as the bioplatform for anchoring N-genetargeted aptamer. In the presence of SARS-CoV-2 N-gene, the immobilized aptamer strands changed their conformation to specifically bind with N-gene. It thus increased the contact area or enlarged the distance between aptamer and the SPR chip, resulting in a change of the SPR signal irradiated by the laser (He-Ne) with the wavelength (λ) of 633 nm. Nb 2 C QDs were derived from Nb 2 C MXene nanosheets via a solvothermal method, followed by functionalization with octadecanethiol through a self-assembling method. Subsequently, the gold chip for SPR measurements was modified with Nb 2 C-SH QDs via covalent binding of the Au-S bond also by self-assembling interaction. Nb 2 C-SH QDs not only resulted in high bioaffinity toward aptamer but also enhanced the SPR response. Thus, the Nb 2 C-SH QD-based SPR aptasensor had low limit of detection (LOD) of 4.9 pg mL −1 toward N-gene within the concentration range 0.05 to 100 ng mL −1 . The sensor also showed excellent selectivity in the presence of various respiratory viruses and proteins in human serum and high stability. Moreover, the Nb 2 C-SH QD-based SPR aptasensor displayed a vast practical application for the qualitative analysis of N-gene from different samples, including seawater, seafood, and human serum. Thus, this work can provide a deep insight into the construction of the aptasensor for detecting SARS-CoV-2 in complex environments.

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We describe the conditions for optimal formation of laser-induced periodic surface structures (LIPSS) over poly(3-hexylthiophene) (P3HT) spin-coated films. Optimal LIPSS on P3HT are observed within a particular range of thicknesses and laser fluences. These conditions can be translated to the photovoltaic blend formed by the 1:1 mixture of P3HT and [6,6]-phenyl C-butyric acid methyl ester (PCBM) when deposited on an indium tin oxide (ITO) electrode coated with (poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). Solar cells formed by using either a bilayer of P3HT structured by LIPSS covered by PCBM or a bulk heterojunction with a P3HT:PCBM blend structured by LIPSS exhibit generation of electrical photocurrent under light illumination. These results suggest that LIPSS could be a compatible technology with organic photovoltaic devices.

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Bilayers of the ferroelectric polymer poly-(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE) on semiconducting poly(3-hexyl thiophene) substrates have been prepared by sequential spin-coating. Here, we present a study of the polarization of this ferroelectric/semiconducting bilayer as a function of the semiconductor thickness by piezoresponse force microscopy. The structural and morphological details have been investigated by a combination of grazing incidence wide-angle X-ray scattering and contact angle measurements. The obtained results show that the presence of a semiconducting polymer layer between a silicon substrate and the ferroelectric polymer layer stabilizes the polarization induced by an external field.