Publications by authors named "Mingdi Xu"

Diffusion is defined as general mechanism for drug release from advanced delivery systems, yet dynamic structure of dosage form intrinsically plays an unknown role. The synchrotron radiation X-ray micro-computed tomography (SR-μCT) three-dimensional (3D) imaging and in-depth analysis of 3D structures were applied to readily differentiate materials and accurately capture internal structure changes of multiple unit pellet system (MUPS) and the constituent pellets, visualizing internal 3D structure of a MUPS of theophylline tablets for their 3 levels hierarchy structures: pellets with rapid drug release characteristics, a protective cushion layer and a matrix layer. Drug release pathways were extracted from SR-μCT images and a 3D maze network was constructed using pore network analysis to quantify the internal structural evolution during drug release.

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The structures of solid dosage forms determine their release behaviors and are critical attributes for the design and evaluation of the solid dosage forms. Here, the 3D structures of doxazosin mesylate sustained-release tablets were parallelly assessed by micro-computed tomography (micro-CT). There were no significant differences observed in the release profiles between the RLD and the generic formulation in the conventional dissolution, but the generic preparation released slightly faster in media with ethanol during an alcohol-induced dose-dumping test.

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Significance: In hyperscanning studies of natural social interactions, behavioral coding is usually necessary to extract brain synchronizations specific to a particular behavior. The more natural the task is, the heavier the coding effort is. We propose an analytical approach to resolve this dilemma, providing insights and avenues for future work in interactive social neuroscience.

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Our motor system uses sensory feedback to keep desired performance. From this view, motor fluctuation is not simply 'noise' inevitably caused in the nervous system but would play a role in generating variations to explore better outcomes via sensory feedback. Vocalization system offers a good model for studying such sensory-motor interactions since we regulate vocalization by hearing our own voice.

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In this work, a split-type dual-mode (colorimetric/photothermal) immunoassay method was designed for point-of-care testing (POCT) detection of mycotoxins (aflatoxin B, AFB as the model analyte) in foodstuffs based on Pt supported on nitrogen-doped carbon amorphous (Pt-CN). The as-synthesized Pt-CN exhibits excellent peroxidase-mimicking activity, which can catalyze the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) into TMB with sensitive colorimetric readout in the presence of hydrogen peroxide (HO). Moreover, the TMB also serves as a near-infrared (NIR) photothermal agent to convert the colorimetric readout into heat under the irradiation of an 808 nm laser.

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In-depth exploration of the local surface plasmon resonance and piezoelectric effects associated with metal can help develop efficient biosensors. Here, we presented for the first time the localized surface plasmon resonance (LSPR) and piezoelectric effects co-enhance the construction of an efficient intra-body phase electric field for the construction of efficient photoelectrochemical (PEC) biosensors. Briefly, the LSPR enhancement and piezoelectric enhancement effects between Ag nanoparticles and the piezoelectric material NaNbO were investigated in a PEC biosensor system under the excitation of portable UV light.

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In this work, we report on a portable photoelectrochemical (PEC) sensing system for telomerase activity detection based on dual biomineralized ZIF-8 nanoparticles (NPs)-medicated conversion of chemical energy to electricity and terminal deoxynucleoside transferase (TdTase)-catalyzed elongation of Y-junction DNA structure. Two kinds of biomineralized ZIF-8 NPs including glucose oxidase (GOx)-encapsulated ZIF-8 (GZIF) and horseradish peroxidase (HRP)-encapsulated ZIF-8 (HZIF) are involved in this assay system. The recognition of telomerase is started with telomerase-catalyzed elongation of a telomerase substrate (TS) primer, which generates a longer elongation chain to trigger the formation of a Y-junction DNA structure.

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Changes in structure of oral solid dosage forms (OSDF) elementally determine the drug release and its therapeutic effects. In this research, synchrotron radiation X-ray micro-computed tomography was utilized to visualize the 3D structure of enteric coated pellets recovered from the gastrointestinal tract of rats. The structures of pellets in solid state and compendium media were measured.

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Research has discovered the modulatory effect of peripheral stimulation simulating altered bodily signals on emotion. Whether such an effect varies depending on one's interoceptive accuracy (IAc) remains unclear. Therefore, we provided haptic stimulation simulating participants' slowed-down heartbeats or no stimulation while they engaged in socially stressful tasks to examine whether participants reacted differently depending on their IAc.

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DNA walkers, a type of dynamic nanomachines, have become the subject of burgeoning research in the field of biology. These walkers are powered by driving forces based on strand displacement reactions, protein enzyme/DNAzyme reactions and conformational transitions. With the unique properties of high directionality, flexibility and efficiency, DNA walkers move progressively and autonomously along multiple dimensional tracks, offering abundant and promising applications in biosensing, material assembly and synthesis, and early cancer diagnosis.

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Construction of multifunctional nonviral gene vectors to execute defined tasks holds great potential for the precise and effective treatment of gene-associated diseases. Herein, we have developed four large π-conjugation triphenylamine derivatives bearing two polar [12]aneN heads and a lipophilic tail for applications in gene delivery, one/two-photon-triggered near-infrared (NIR) fluorescence bioimaging, and combined photodynamic therapy (PDT) and gene therapy of cancer. These compounds possess typical NIR aggregation-induced emission characteristics, mega Stokes shifts, strong two-photon excitation fluorescence, and excellent DNA condensation abilities.

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DNA machines are smart artificial devices that perform well-organized DNA hybridization reactions or nanoscale mechanical movements. Herein, a nanoscale assembly line composing of dual DNA machines is meticulously designed by coupling a catalytic hairpin assembly (CHA)-based machine with a 3D DNA walker machine. Equipped with upconversion nanoparticles (UCNPs) as signal tags, the dual DNA machines-based assembly line (DDMAL) can efficiently amplify the fluorescent signal of target recognition event, enabling sensitive detection of microRNA (miRNA).

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Individuals with autism spectrum disorders (ASD) are impaired not only in social competencies but also in sensory perception, particularly olfaction. The olfactory ability of individuals with ASD has been examined in several psychophysical studies, but the results have been highly variable, which might be primarily due to methodological difficulties in the control of odor stimuli (e.g.

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Vocal control plays a critical role in smooth social communication. Speakers constantly monitor auditory feedback (AF) and make adjustments when their voices deviate from their intentions. Previous studies have shown that when certain acoustic features of the AF are artificially altered, speakers compensate for this alteration in the opposite direction.

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A novel fluorescent sensing platform for telomerase activity assay was developed by coupling a three-dimensional (3D) DNA walker with the MnO nanosheet-upconversion nanoparticle (UCNPs) complex-based fluorescence resonance energy-transfer (FRET) system.

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Developing simple, high-efficiency non-enzyme bioassays is of great importance for modern analytical systems, but remains a significant challenge. One promising route is to utilize highly efficient nanocatalysts with the exposure of active crystal facets. Herein, we for the first time propose a novel colorimetric immunoassay for the ultrasensitive detection of the human prostate-specific antigen (PSA) based on using a unique type of nanolabel - high-index {hk0} faceted platinum concave nanocubes (HIF-Pt-CNCs).

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The present study used functional near-infrared spectroscopy (fNIRS) to measure 5- to 6-month-old infants' hemodynamic response in the prefrontal cortex (PFC) to visual stimuli differing in saliency and social value. Nineteen Japanese 5- to 6-month-old infants watched video clips of Peek-a-Boo (social signal) performed by an anime character (AC) or a human, and hand movements without social signal performed by an AC. The PFC activity of infants was measured by 22-channel fNIRS, while behaviors including looking time were recorded simultaneously.

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This work reports on a novel time-resolved fluorescent aptasensing platform for the quantitative monitoring of adenosine 5'-triphosphate (ATP) by interaction of dispersive/agglomerate gold nanoparticles (AuNPs) with terbium ion-coordinated carbon dots (Tb-CDs). To construct such a fluorescent nanoprobe, Tb-CDs with high-efficient fluorescent intensity are first synthesized by the microwave method with terbium ions (Tb(3+)). The aptasensing system consists of ATP aptamer, AuNP and Tb-CD.

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Herein, gold-silver bimetallic nanoclusters (Au-Ag NCs) with the high fluorescent intensity were first synthesized successfully and utilized for the fabrication of sensitive and specific sensing probes toward inorganic pyrophosphatase (PPase) activity with the help of copper ion (Cu(2+)) and inorganic pyrophosphate ion (PPi). Cu(2+) was used as the quencher of fluorescent Au-Ag NC, while PPi was employed as the hydrolytic substrate of PPase. The system consisted of PPi, Cu(2+) ion, and bovine serum albumin (BSA)-stabilized Au-Ag NC.

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A new label-free DNA sensing protocol was designed for fluorescent detection of mercury(II) (Hg(2+)), coupling hairpin DNA-scaffolded silver nanocluster (DNA-AgNC) with exonuclease III-assisted target recycling amplification. The assay was carried out through target-induced conformational change of hairpin DNA, while the signal derived from the formed silver nanoclusters on hairpin DNA probes. Initially, target Hg(2+) was specifically coordinated with thymine-thymine (T-T) mismatches to form an intact hairpin DNA.

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A new colorimetric immunosensing platform accompanying enzyme cascade amplification strategy was fabricated for quantitative screening of small-molecular mycotoxins (aflatoxin B, AFB used in this case) coupling with enzyme-controlled dissolution of MnO nanoflakes. The visual colored assay was executed by high-efficient MnO-3,3',5,5'-tetramethylbenzidine (TMB) system (blue). In the presence of ascorbic acid, MnO nanoflakes were dissolved into Mn ions, thus resulting in a perceptible color change from blue to colorless.

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A simple, low-cost transducer with glucometer readout was designed for sensitive detection of mercury(II) (Hg(2+)), coupling with thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination chemistry and invertase-functionalized gold-dendrimer nanospheres for the signal amplification. Initially, nanogold-encapsulated poly(amidoamine) dendrimers (Au DENs) were synthesized by in-situ reduction of gold(III). Thereafter, the as-prepared Au DENs were utilized for the labeling of invertase and T-rich signal DNA probe.

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An ultrasensitive photoelectrochemical (PEC) immunoassay protocol for quantitative detection of low-abundant proteins at a low potential was designed by utilizing porphyrin-sensitized titanium dioxide (TiO2) nanostructures. Experimental results demonstrated that the water-soluble 5,10,15,20-tetra(4-sulfophenyl)-21H,23H-porphyrin (TSPP) could be bound onto titanium dioxide via the sulfonic group. TSPP-sensitized TiO2 nanostructures exhibited better photoelectrochemical responses and stability in comparison with TiO2 nanoparticles alone under continuous illumination.

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Photoelectrochemical (PEC) detection is an emerging and promising analytical tool. However, its actual application still faces some challenges like potential damage of biomolecules (caused by itself system) and intrinsic low-throughput detection. To solve the problems, herein we design a novel split-type photoelectrochemical immunoassay (STPIA) for ultrasensitive detection of prostate specific antigen (PSA).

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A new signal-amplification strategy based on copper(II) (Cu(2+))-dependent DNAzyme was developed for sensitive impedimetric biosensing of Cu(2+) in aqueous solution by coupling with target-induced formation of hemin/G-quadruplex-based DNAzyme and enzymatic catalytic precipitation technique. Initially, the target analyte cleaved the Cu(2+)-specific DNAzyme to generate an initiator strand on the sensor. Thereafter, the initiator strand underwent an unbiased strand-displacement reaction between hairpin probes in turn to construct a nicked double-helix, accompanying the formation of hemin/G-quadruplex DNAzyme on the long duplex DNA.

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