Temperature-Responsive Nanocarrier-Regulated Alternative Release of "Cargos" for a Multiplex Photoelectrochemical Bioassay of Antibiotic-Resistant Genes

A smart temperature stimuli-driven multiplex photoelectrochemical (PEC) assay was constructed for antibiotic resistance genes (ARGs) detection, where the stimuli-responsive gatekeeping by regulating the alternative release of "cargo" allowed for the simultaneous detection of multiple tetracycline resistance gene, using tetA (T_DNA1) and tetC (T_DNA2) as the model. Dual temperature-responsive nanoassemblies were embedded in the PEC bioassay as signal DNA tages: one thermoresponsive polymer (poly(N-isopropylacrylamide), PNIPAM)-capped mesoporous silica nanoparticles (MSN) with loading the "cargo" of HgO nanoparticles as signal DNA1 tags (S_DNA1-PNIPAM@MSN@HgONPs) and the other antimony tartrate (SbT)-anchored silica nanospheres as signal DNA2 tags (S_DNA2-SbT@SiO₂NSs). At 20 °C, below the lower critical solution temperature (LCST) of PNIPAM, the "gatekeeper" PNIPAM in S_DNA1-PNIPAM@MSN@HgONPs was in an ON state, igniting Hg²⁺ release through the pore of SiO₂. While at above LCST (40 °C), it was in an OFF state. Likewise, the thermo-dependent dissociation of SbT endowed the grafted S_DNA2 tags switching from the OFF (at 20 °C) to ON state (at 40 °C), igniting SbO⁺ release. The released Hg²⁺ and SbO⁺ triggered the amplified photocurrents due to the structure evolution of the photoactive layer into HgS/ZnS or Sb₂S₃/ZnS heterostructure, thus achieving sensitive detection of multiple ARGs: tetA, tetC, tetG, tetM, tetO, tetZ, tetX, and tetW. Combined with heat map analysis, rapid screening of the ARGs profiles in 12 samples could be realized. This bioassay is simple and accessible for multiple genes analysis with the detection limit down to 0.50 nM. And it was successfully applied for measuring tetracycline ARGs in real sludge samples.

Mixed Solvothermal Synthesis of Tn Cluster-Based Indium and Gallium Sulfides Using Versatile Ammonia or Amine Structure-Directing Agents

Metal chalcogenide supertetrahedral Tn clusters are of current interest for their unique compositions and structures, which rely highly on the structure-directing agents. Herein, we report four novel Tn cluster-based indium and gallium sulfides, namely, [NH(CH₃)₃]₄In₄S₁₀H₄ (1), (NH₃)₄Ga₄S₆ (2), [NH₃CH₂CH₃]₅(NH₂CH₂CH₃)₂Ga₁₁S₁₉ (3), and [NH₃CH₂CH₂OH]₆Ga₁₀S₁₈·2NH₂CH₂CH₂OH (4). All four compounds were solvothermally synthesized in mixed amine-ethanol solutions or deep eutectic solvent (DES), where ammonia/amine molecules play significant structure-directing roles in the speciation and crystal growth. (1) Being protonated, the trimethylamine and ethanolamine molecules surround the T2-[In₄S₁₀H₄]^4- clusters (for 1) and [Ga₁₀S₁₈]_n^6n- open framework (for 4), respectively, compensating for the negative charge of the inorganic moieties. (2) With the lone pair of electrons, the ammonia molecules in 2 coordinate directly to corner Ga³⁺ ions of the {Ga₄S₆} cage to give a neutral T2-(NH₃)₄Ga₄S₆ cluster. (3) For compound 3, part of the ethylamine molecules act as terminating ligands for the T1 and T3 units in the [Ga₁₁S₁₉(NH₂CH₂CH₃)₂]_n^5n- layer, while the rest act as interlamellar countercations upon protonation. Theoretical studies reveal the contributions of N, C, and H to the density of states (DOS) for 2 and 3 because of their hybrid structures that combine the ammonia/amine ligands with sulfide moieties together.

Preparation and Enhanced Catalytic Hydrogenation Activity of Sb/Palygorskite (PAL) Nanoparticles

A Sb/palygorskite (PAL) composite was synthesized by a facile solvothermal process and applied in catalytic hydrogenation of p-nitrophenol for the first time. It was found that the Sb nanoparticles with the sizes of 2-5 nm were well dispersed on the fiber of PAL, while partial aggregated Sb nanoparticles with sizes smaller than 200 nm were also loaded on the PAL. The Sb/PAL composite with 9.7% Sb mass amounts showed outstanding catalytic performance by raising the p-nitrophenol conversion rate to 88.3% within 5 min, which was attributed to the synergistical effect of Sb and PAL nanoparticles facilitating the adsorption and catalytic hydrogenation of p-nitrophenol.