Publications by authors named "Zhidong Ma"

Article Synopsis
  • Uncontrolled bleeding is a major cause of preventable deaths after traumatic injuries in military and civilian settings.
  • A chitosan-based cryogel was engineered using a unique cross-linking method, resulting in a material with excellent structure, mechanical properties, and fluid absorption.
  • Testing in animal models showed that this cryogel significantly reduced blood loss and hemostasis time, proving its effectiveness and biocompatibility as a potential treatment for severe hemorrhage.
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Hyaluronic acid (HA), a major component of skin extracellular matrix, provides an excellent framework for hemostatic design; however, there still lacks HA materials tailored with superior mechanical properties to address non-compressible hemorrhages. Here, we present a solvent-free thermal approach for constructing a shape-memory HA sponge for this application. Following facile thermal incubation around 130 °C, HA underwent cross-linking via esterification with poly(acrylic acid) within the sponge pre-shaped through a prior freeze-drying process.

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Toll-like receptor (TLR) agonists can act as immune stimulants alone or as part of alum or oil formulations. Humoral and cellular immune responses were utilized to assess quantitative and qualitative immune response enhancement by TLR agonists using recombinant protective antigen (rPA) of B. anthracis as a model antigen.

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Influenza hemagglutinin (HA) is considered a major protective antigen of seasonal influenza vaccine but antigenic drift of HA necessitates annual immunizations using new circulating HA versions. Low variation found within conserved non-HA influenza virus (INFV) antigens may maintain protection with less frequent immunizations. Conserved antigens of influenza A virus (INFV A) that can generate cross protection against multiple INFV strains were evaluated in BALB/c mice using modified Vaccinia virus Ankara (MVA)-vectored vaccines that expressed INFV A antigens hemagglutinin (HA), matrix protein 1 (M1), nucleoprotein (NP), matrix protein 2 (M2), repeats of the external portion of M2 (M2e) or as tandem repeats (METR), and M2e with transmembrane region and cytoplasmic loop (M2eTML).

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With the rapid development of technology, information security has always been considered a major challenge. In this work, the excellent combination of persistent luminescence, photoluminescence, up-conversion luminescence, and thermo-luminescence in a particular material ZnBO:Tb,Yb synthesized via a solid-state reaction is reported, which can be used for the information encryption and anti-counterfeiting. Tb ions were chosen as the emitting centers for multimodal emissions, and Yb codoping can be used as electron traps and sensitizer to adjust trap distribution and efficient up-conversion luminescence in rare-earth-doped luminescent materials.

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In this work, a layered melilite structure, CaLaAlO, was synthesized and observed to have obvious luminescence behaviors under the stimuli of ultraviolet light and rubbing, which were called photoluminescence and triboluminescence, respectively. Considering the wide bandgap of CaLaAlO and its specific crystal structure, the observed luminescence should be attributed to intrinsic defects. Both the photoluminescence and triboluminescence of CaLaAlO show a strong dependence on the synthesis atmosphere, suggesting that they should be related to the oxygen vacancy.

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Anticounterfeiting is a vitally important issue in modern society. At present, the most commonly used luminescent anticounterfeiting technique is based on static photoluminescence (PL), which is easily counterfeited by certain substitutes. In this work, we report for the first time a dynamic PL material, NaCaGeO:Tb.

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The development of luminescent materials for anticounterfeiting and encryption is of great importance. Herein, we develop a multistimuli-responsive luminescent material, NaCaGeO:Pb/Er, and use it to print luminescent images. The photoluminescence and upconversion luminescence of these images show different patterns and colors under different stimuli.

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Calcium [Ca(II)] is a fundamental transducer of electrical activity in the central nervous system (CNS). Influx of Ca(II) into the cytosol is responsible for action potential initiation and propagation, and initiates interneuronal communication via release of neurotransmitters and activation of gene expression. Despite the importance of Ca(II) in physiology, it remains a challenge to visualize Ca(II) flux in the central nervous system (CNS) in vivo.

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Porphyrazines (Pz), or tetraazaporphyrins, are being studied for their potential use in detection and treatment of cancer. Here, an amphiphilic Cu-Pz-Gd(III) conjugate has been prepared via azide-alkyne Huisgen cycloaddition or 'click' chemistry between an azide functionalized Pz and alkyne functionalized DOTA-Gd(III) analog for use as an MRI contrast agent. This agent, Cu-Pz-Gd(III), is synthesized in good yield and exhibits solution-phase ionic relaxivity (r1  = 11.

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After the manner in which coenzymes often participate in the binding of substrates in the active sites of enzymes, pillar[5]arene, a macrocycle containing five hydroquinone rings linked through their para positions by methylene bridges, modifies the binding properties of cucurbit[6]uril, such that the latter templates azide-alkyne cycloadditions that do not occur in the presence of only the cucurbit[6]uril, a macrocycle composed of six glycoluril residues doubly linked through their nitrogen atoms to each other by methylene groups. Here, we describe how a combination of pillar[5]arene and cucurbit[6]uril interacts cooperatively with bipyridinium dications substituted on their nitrogen atoms with 2-azidoethyl- to 5-azidopentyl moieties to afford, as a result of orthogonal templation, two [4]rotaxanes and one [5]rotaxane in >90% yields inside 2 h at 55 °C in acetonitrile. Since the hydroxyl groups on pillar[5]arene and the carbonyl groups on cucurbit[6]uril form hydrogen bonds readily, these two macrocycles work together in a cooperative fashion to the extent that the four conformational isomers of pillar[5]arene can be trapped on the dumbbell components of the [4]rotaxanes.

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Interspin distances between 0.8 nm and 2.0 nm can be measured through the dipolar broadening of the continuous wave (cw) EPR spectrum of nitroxide spin labels at X-band (9.

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Platinum-based drugs have been used to successfully treat diverse cancers for several decades. Cisplatin, the original compound of this class, cross-links DNA, resulting in cell cycle arrest and cell death via apoptosis. Cisplatin is effective against several tumor types, yet it exhibits toxic side effects and tumors often develop resistance.

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The reactivity of two DNA-targeted platinum-acridine conjugates with cysteine sulfur was studied. The conjugate containing an amidine-NH donor group cis to the chloride leaving group showed considerably reduced reactivity with N-acetylcysteine compared to the prototypical derivative containing a thiourea-S linkage. The opposite scenario has been observed previously in reactions with nucleobase nitrogen.

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The cytotoxic complex, [PtCl(Am)2(ACRAMTU)](NO3)2 (1) ((Am)2 = ethane-1,2-diamine, en; ACRAMTU = 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea), is a dual platinating/intercalating DNA binder that, unlike clinical platinum agents, does not induce DNA cross-links. Here, we demonstrate that substitution of the thiourea with an amidine group leads to greatly enhanced cytotoxicity in H460 non-small-cell lung cancer (NSCLC) in vitro and in vivo. Two complexes were synthesized: 4a (Am2 = en) and 4b (Am = NH3), in which N-[2-(acridin-9-ylamino)ethyl]-N-methylpropionamidine replaces ACRAMTU.

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Novel thiourea- and guanidine-modified acridine-4-carboxamides (4, 7) and a corresponding platinum-intercalator conjugate (4') have been synthesized and evaluated as cytotoxic agents in human promyelocytic leukemia, HL-60, and a non-small cell lung cancer, NCI-H460. Modification of thiourea sulfur in derivative 4 with a DNA platinating moiety, giving 4', resulted in a pronounced cytotoxic enhancement, and the conjugate proved to be the most active of the newly synthesized compounds in NCI-H460 cells. Conjugate 4' represents a new chemotype with potential applications in the treatment of chemoresistant tumors.

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The 9-aminoacridine chromophore is an important building block of DNA-targeted chemotherapeutic agents. The success of 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea as a carrier group in cytotoxic platinum-intercalator conjugates prompted us to explore the synthesis of an analogous guanidine-functionalized acridine. In a successful effort to generate such a derivative, various methods of guanidylation were employed, which demonstrate that the acridine C9-N9 linkage is highly susceptible to electrophilic and nucleophilic attack.

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The polarographic behavior of the reaction product of formaldehyde and phenyldrazine hydrochloride on the drop mercury electrode was investigated in a medium of 0.01 mol/L H3PO4 and sensitive second order polarographic reduction wave was obtained at -0.76 V (vs.

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A coordinated functional genomics program was implemented to identify secreted polypeptides with therapeutic applications in the treatment of diabetes. Secreted factors were predicted from a diverse expressed-sequence tags (EST) database, representing >1,000 cDNA libraries, using a combination of bioinformatic algorithms. Subsequently, approximately 8,000 human proteins were screened in high-throughput cell-based assays designed to monitor key physiological transitions known to be centrally involved in the physiology of type 2 diabetes.

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