POMOF/SWNT Nanocomposites with Prominent Peroxidase-Mimicking Activity for l-Cysteine “On–Off Switch” Colorimetric Biosensing

Abstract

In order to explore novel colorimetric biosensors with high sensibility and selectivity, two new Keggin polyoxometalates (POMs)-based Cu-trz (1,2,4-triazole) metal–organic frameworks (MOFs) with suitable specific surface areas and multiple active sites were favorably fabricated; then single-walled carbon nanotubes (SWNTs) were merged with new POMOFs to construct POMOF/SWNT nanocomposites. Herein, POMOF/SWNT nanocomposites as peroxidase mimics were explored for the first time, and the peroxidase-mimicking activity of the prepared POMOF/SWNT nanocomposites is heavily dependent on the mass ratio of POMOFs and SWNTs, in which the maximum activity is achieved at the mass ratio of 2.5:1 (named PMNT-2). More importantly, PMNT-2 exhibits the lowest limit of detection (0.103 μM) among all reported materials to date and the assumable selectivity toward l-cysteine (l-Cys) detection. With these findings, a convenient, sensitive, and effective “on–off switch” colorimetric platform for l-Cys detection has been successfully developed, providing a promising prospect in the biosensors and clinical diagnosis fields.

Bacterium, Fungus, and Virus Microorganisms for Energy Storage and Conversion

“…Similar to the bacteria microorganisms, fungi can be carbonized to heteroatom-doped carbon materials, which can be utilized as the active or support materials for electrodes. In this section, we will review the typical fungi (e.g., A. Niger, [7] Aspergillus flavus, [98] Trichoderma viride, [10] Neurospora crassa, [107] yeast, [108] Portobello mushroom (PM), [106] Bamboo fungus [43] ) and their carbonization derivatives to illustrate the potential in the energy-related fields, including lithium-ion batteries, lithium-sulfur batteries, and oxygen reduction reaction.…”

“…niger is one of the ubiquitous fungal species belonging to ascomycetes subphylum, filariformes, and plexiculariaceae. [7] The hyphae are protruding from the center with a diameter of 15-20 pm and a length of 1-3 mm. On the top of the hyphae, there exists a spherical parietal capsule with an outlayer of small pedicels, which are covered with clusters of brown-black spheres (2.5-4.0 µm).…”

“…The formation of NbC nanoparticles can generate the porous nanostructure and enhance electronic conductivity as well as suppress the shuttling effect of the soluble polysulfides. Furthermore, Li et al [7] reported a metal-A. niger bioleaching method to combine the metal sulfides with the N-doped carbon microfibers (MS@NCF, MS = ZnS, Co 9 S 8 , FeS, Cu 1.81 S) as anodes in LIBs.…”

“…Due to the limited fossil energy sources and deteriorating environments, it is of increasing importance to develop highly efficient and clean energy sources (e.g., solar energy, wind energy, and chemical energy) as alternatives to the fossil fuels, which can generate sufficient secondary electric energy for the society. [1,2] Therefore, to effectively use these generated electric energy, developing reliable green energy storage and conversion devices, such as lithium-/sodium-ion batteries (LIBs [3,4] /SIBs [5][6][7] ), supercapacitors (SC), [8] lithium-sulfur batteries (LSBs), [9][10][11][12] lithium-oxygen (Li-O 2 ) batteries, [13][14][15] and fuel cells, [16] is the key solution.…”

“…[45,49] Interestingly, bacterium and fungus cells both have the abilities to adsorb and reduce the metal ions to in situ synthesize metal-contained materials on/inside the sturdy cell wall. [26,30] Thus, bacterium and fungus cells can be utilized as promising templates for the growth of metal nanoparticles (NPs) and metal composites (including metal oxides, [50,51] metal sulfides, [7,52] and metal phosphates [19,53] ) due to their biomineralization abilities. For instance, metal nanoparticles including Pt, [25] palladium (Pd), [31,54] Au, [26] Cu, [30] and Ag [55] were reduced by Shewanella and Geobacter bacteria in this bioinspired method, which could enhance the catalytic activities in oxygen reduction reaction (ORR) and lithium-oxygen batteries.…”