Synergistic photoinduced charge transfer resonance from porous ZIF-67 decorated violet phosphorus array for SERS immunoassay of SARS-CoV-2 spike protein.

As a rapid, highly sensitive, and user-friendly technique, surface-enhanced Raman scattering (SERS) has an extraordinary appeal to home self-test of COVID-19 during the post pandemic era. However, most of the existing SERS substrates have been still criticized in stability, repeatability, and sample enrichment. To address these obstacles, a novel non-metallic SERS substrate with porous surfaces and array geometry was developed by in-situ growing ZIF-67 particles on two-dimensional violet phosphorus (VP) matrix. Chemical enhancement was prominently promoted by the synergistic photoinduced charge transfer resonance in the hybrid band structure of the ZIF-67@VP substrate, facilitating a noble metal-similar enhancement factor of 6.11 × 107. The biocompatible ZIF-67@VP porous array with attractive enhancement capability and high anchoring efficiency was further utilized to monitoring SARS-CoV-2 spike protein in practical saliva samples based on a sandwich immunostructure, achieving a limit of detection of 1.7 ng/mL assisted by black phosphorus nanosheets. This nonmetallic immunoassay strategy with exceptional sensitivity and specificity is predicted to extend the utilization of SERS obstacle in daily infectious disease screening.

Regulation of recombinant humanized collagen on HAP growth and its molecule simulation.

Hydroxyapatite (HAP) in natural bone is formed under the regulation of natural collagen I. Here, we report how recombinant humanized collagen I (rhCol I) regulates the growth of HAP nanocrystals in a long belt shape 100-150 nm in width and 200-300 nm in length. MD simulation results showed that the interactions between rhCol I and the (001), (100), and (211) planes of HAP mainly contributed to the electrostatic force and van der Waals forces via COO⋯Ca, -NH⋯Ca, CH⋯OPO3, and NH⋯OPO3 bonds, respectively. On the (001) plane, the interaction between -COO- and Ca was stronger than on the (100) and (211) planes, resulting in a large electrostatic force, which inhibited the growth of the (001) plane. The lowest energy of adsorption to the (211) plane resulted in the preferential growth of the (211) plane due to the weakest interaction with rhCol I. The detailed correlation between HAP and rhCol I could explain HAP growth under regulation by rhCol I. This study provides a reference for the bio-application of recombinant collagen.

In situ cyclodextrin metal-organic framework/electrospun composite fibers with biosafety for the removal of volatile organic compounds.

Volatile organic compounds (VOCs) are one of the most common air pollutants, which threaten human health seriously. Fibrous textile is one of the most popular matrices for VOC removal in daily life. In this study, biosafe cyclodextrin metal-organic framework/polycaprolactone (CD-MOF/PCL) electrospun fibers were prepared via a CD precursor doping method, followed by hydrothermal treatment in methanol vapor diffusion. In situ CD-MOF crystals with a high loading of more than 50 wt% densely covered the surface of the electrospun fibers. The CD-MOF/PCL composite fibers show similar stress-strain behavior to the electrospun PCL fibers. The analysis of the fractured zone indicated that the compatibility of CD-MOF/PCL fibers was excellent, and CD-MOF showed no obvious peeling-off, even at low temperatures. The hemolysis rate of less than 1% confirms the biosafety of the composite materials. Further, the CD-MOF crystals anchored onto the fibers promote their VOC uptakes significantly. The CD-MOF/PCL fibrous matrix, which demonstrated compatibility, excellent strength, and biosafety would be beneficial to develop novel equipment to purify air pollution.