Shengnian Wang

Dopamine is a key neurotransmitter and neuromodulator that regulates many critical brain functions. Accurate monitoring of its level is essential for neuroscience as well as the diagnosis and treatment of many brain diseases. In this work, we developed a new electrochemical sensor, comprising phosphorus-doped graphitic carbon nitride (P-g-C₃N₄) and zeolitic imidazolate framework 67 (ZIF-67), for dopamine detection. In this composite electrode material, ZIF-67 provides numerous adsorption and sensing sites, while P-g-C₃N₄ enhances overall electrical conductivity and stability. Cyclic voltammetry tests reveal the redox behavior of dopamine at the surface of the composite electrode across various pH values and scan rates. Using differential pulse voltammetry, the sensitivity and selectivity of this dopamine sensor were assessed, identifying a limit of detection of 0.39 nM. Further successful quantification of dopamine in urine samples suggests the potential practical use of this new composite electrochemical sensor for detecting dopamine and/or other neurotransmitters.

We investigate the defect-dependent electronic structure and gas-sensing potential of cubic α-CsPbI₃ using first-principles density functional theory and nonadiabatic molecular dynamics. Among the intrinsic defects, interstitials, vacancies, antisites, and switches studied, the I_Pb and Pb_I antisite defects exhibit transition energy levels near the middle of the band gap, thus functioning as deep traps. Short-term adsorption of ammonia selectively modifies the electronic structure, coordinating with Pb at Pb_I sites and Cs at I_Pb sites, significantly altering recombination pathways. Detailed analysis reveals that NH₃ reduces anharmonicity at I_Pb defects, enabling enhanced recombination at elevated temperatures, while trap-assisted recombination dominates at room temperature. Other analytes, including CH₃NH₂ and NO₂, show negligible impact on the band gap or recombination dynamics, highlighting the potential selectivity of NH₃ interactions. Ab initio nonadiabatic molecular dynamics simulations at 300 K and 600 K further demonstrate temperature-dependent modulation of carrier lifetimes, with NH₃ accelerating recombination at ambient conditions and suppressing certain pathways at higher temperatures. These findings suggest that α-CsPbI₃ can serve as a selective and sensitive ammonia sensor over a broad temperature range and offer insights for ammonia detection under industrially relevant conditions.

Diabetic wound healing is often hindered by poor outcomes, prolonged recovery, and high recurrence. To address this, a new therapy approach was demonstrated in this study, in which ginsenoside (GS) molecules are incorporated into small extracellular vesicles (sEV) secreted by mesenchymal stem cells (MSCs), and the formed complexes are then anchored in DNA hydrogels via aptamer‐CD63 affinity as “GS/sEV@DNAgels”. Besides the tissue‐restorative ability that sEVs inherit from MSCs, in GS/sEV@DNAgels, GS molecules provide a superior antimicrobial/anti‐inflammatory environment at wound sites, while DNA hydrogels serve as wound dressings to ensure sustained release kinetics and enhanced skin penetration. An innovative ultrasonic stimulation was developed to promote the massive production of sEVs. By triggering multiple cellular responses that alter membrane fluidity, calcium levels, and relevant protein expression, our approach achieves a 57.7‐fold increase in sEV yield. The synergistic effects of GS and sEVs enhance cell viability, migration, and angiogenesis, as well as local anti‐inflammatory and antibacterial conditions during diabetic wound healing. The upregulation of miR‐424/322 is confirmed as an essential mechanism of this GS/sEV@DNAgel system in accelerating skin restoration. Our work provides a new and promising strategy for diabetic tissue regeneration.

We investigate the defect-dependent electronic structure and gas-sensing potential of cubic α-CsPbI₃ using first-principles density functional theory and nonadiabatic molecular dy-namics simulations. Among the intrinsic defects, interstitials, vacancies, antisites, and switches studied, the IPb and PbI antisite defects exhibit transition energy levels near the middle of the band gap, thus functioning as deep traps. Short-term adsorption of ammo-nia selectively modifies the electronic structure, coordinating with Pb at PbI sites and Cs at IPb sites, significantly altering recombination pathways. Detailed analysis reveals that NH3 reduces anharmonicity at IPb defects, enabling enhanced recombination at elevated tem-peratures, while trap-assisted recombination dominates at room temperature. Other ana-lytes, including CH3NH2 and NO2, show negligible impact on the band gap or recombina-tion dynamics, highlighting the selectivity of NH3 interactions. Ab initio nonadiabatic mo-lecular dynamics simulations at 300 K and 600 K further demonstrate tempera-ture-dependent modulation of carrier lifetimes, with NH3 accelerating recombination at ambient conditions and suppressing certain pathways at higher temperatures. These findings suggest that α-CsPbI₃ can serve as a selective and sensitive ammonia sensor over a broad temperature range and offer insights for ammonia detection under industrially relevant conditions.

A novel electrochemical sensor (P-g-C₃N₄/MOF-199/CPE) was developed to determine the metformin concentration in pharmaceutical samples. In this sensor, the copper units of MOF-199 of the composite electrode specifically capture metformin molecules so that the sensing selectivity is remarkably improved. Phosphorus-doped graphitic carbon nitrides (P-g-C₃N₄) further enhance the electrical conductivity and sensitivity of the sensor. The physical and chemical properties of these electrode modifiers were first characterized, followed by electrochemical sensing tests of metformin under different scan rates and pH values. A 39-fold increase in the electrooxidation current of metformin was found in this composite electrode when compared to its bare carbon paste counterpart. A limit of detection (LOD) of 0.15 nM was achieved in the linear sensing range of 0.5 to 1200 nM for metformin. The sensor also showed good reliability and recovery when detecting metformin in pharmaceutical samples. For the first time, we addressed the appearance of adsorption-based peaks in the voltammograms of electrochemical sensors for metformin as a common feature when copper ions are incorporated into the electrode structure. The electrochemical mechanism of metformin was also illustrated by highlighting the hydrolysis of oxime. The nature of all pH-dependent anodic and cathodic peaks in our sensing results confirms the proposed mechanism.

The recent success of mRNA therapeutics against pathogenic infections has increased interest in their use for other human diseases including cancer. However, the precise delivery of the genetic cargo to cells and tissues of interest remains challenging. Here, we show an adaptive strategy that enables the docking of different targeting ligands onto the surface of mRNA-loaded small extracellular vesicles (sEVs). This is achieved by using a microfluidic electroporation approach in which a combination of nano- and milli-second pulses produces large amounts of IFN-γ mRNA-loaded sEVs with CD64 overexpressed on their surface. The CD64 molecule serves as an adaptor to dock targeting ligands, such as anti-CD71 and anti-programmed cell death-ligand 1 (PD-L1) antibodies. The resulting immunogenic sEVs (imsEV) preferentially target glioblastoma cells and generate potent antitumour activities in vivo, including against tumours intrinsically resistant to immunotherapy. Together, these results provide an adaptive approach to engineering mRNA-loaded sEVs with targeting functionality and pave the way for their adoption in cancer immunotherapy applications.

The logic in the design of a halide-mixed APb(I_1−xBr_x)₃ perovskite is quite straightforward: to combine the superior photovoltaic qualities of iodine-based perovskites with the increased stability of bromine-based perovskites. However, even small amounts of Br doped into the iodine-based materials leads to some instability. In the present report, using first-principles computations, we analyzed a wide variety of α-CsPbI₂Br and β-CsPbI₂Br phases, compared their mixing enthalpies, explored their oxidative properties, and calculated their hole-coupled and hole-free charged Frenkel defect (CFD) formations by considering all possible channels of oxidation. Nanoinclusions of bromine-rich phases in α-CsPbI₂Br were shown to destabilize the material by inducing lattice strain, making it more susceptible to oxidation. The uniformly mixed phase of α-CsPbI₂Br was shown to be highly susceptible towards a phase transformation into β-CsPbI₂Br when halide interstitial or halide vacancy defects were introduced into the lattice. The rotation of PbI₄Br₂ octahedra in α-CsPbI₂Br allows it either to transform into a highly unstable apical β-CsPbI₂Br, which may phase-segregate and is susceptible to CFD, or to phase-transform into equatorial β-CsPbI₂Br, which is resilient against the deleterious effects of hole oxidation (energies of oxidation >0 eV) and demixing (energy of mixing 2Br offers an opportunity to obtain a mixed perovskite material with enhanced photostability and an intermediate bandgap between its constituent perovskites.