Discovery and characterization of potent pan-variant SARS-CoV-2 neutralizing antibodies from individuals with Omicron breakthrough infection

The SARS-CoV-2 Omicron variant evades most currently approved neutralizing antibodies (nAbs) and caused drastic decrease of plasma neutralizing activity elicited by vaccination or prior infection, urging the need for the development of pan-variant antivirals. Breakthrough infection induces a hybrid immunological response with potentially broad, potent and durable protection against variants, therefore, convalescent plasma from breakthrough infection may provide a broadened repertoire for identifying elite nAbs. We performed single-cell RNA sequencing (scRNA-seq) and BCR sequencing (scBCR-seq) of B cells from BA.1 breakthrough-infected patients who received 2 or 3 previous doses of inactivated vaccine. Elite nAbs, mainly derived from the IGHV2-5 and IGHV3-66/53 germlines, showed potent neutralizing activity across Wuhan-Hu-1, Delta, Omicron sublineages BA.1 and BA.2 at picomolar NT50 values. Cryo-EM analysis revealed diverse modes of spike recognition and guides the design of cocktail therapy. A single injection of paired antibodies cocktail provided potent protection in the K18-hACE2 transgenic female mouse model of SARS-CoV-2 infection.

Multi-omics blood atlas reveals unique features of immune and platelet responses to SARS-CoV-2 Omicron breakthrough infection

Although host responses to the ancestral SARS-CoV-2 strain are well described, those to the new Omicron variants are less resolved. We profiled the clinical phenomes, transcriptomes, proteomes, metabolomes, and immune repertoires of >1,000 blood cell or plasma specimens from SARS-CoV-2 Omicron patients. Using in-depth integrated multi-omics, we dissected the host response dynamics during multiple disease phases to reveal the molecular and cellular landscapes in the blood. Specifically, we detected enhanced interferon-mediated antiviral signatures of platelets in Omicron-infected patients, and platelets preferentially formed widespread aggregates with leukocytes to modulate immune cell functions. In addition, patients who were re-tested positive for viral RNA showed marked reductions in B cell receptor clones, antibody generation, and neutralizing capacity against Omicron. Finally, we developed a machine learning model that accurately predicted the probability of re-positivity in Omicron patients. Our study may inspire a paradigm shift in studying systemic diseases and emerging public health concerns.

Free CA125 promotes ovarian cancer cell migration and tumor metastasis by binding Mesothelin to reduce DKK1 expression and activate the SGK3/FOXO3 pathway

Objective: CA125/MUC16 is an O-glycosylated protein that is expressed on the surfaces of ovarian epithelial cells. This molecule is a widely used tumor-associated marker for diagnosis of ovarian cancer. Recently, CA125 was shown to be involved in ovarian cancer metastasis. The purpose of this study was to investigate the mechanism of CA125 during ovarian cancer metastasis.

Methods: We analyzed the Oncomine and CSIOVDB databases to determine the expression levels of DKK1 in ovarian cancer. DKK1 expression levels were upregulated or downregulated and applied with CA125 to Transwell and Western blot assays to ascertain the underlying mechanism by which CA125 stimulates cell migration via the SGK3/FOXO3 pathway. Anti-mesothelin antibodies (anti-MSLN) were used to block CA125 stimulation. Then the expression levels of DKK1were tested by enzyme-linked immunosorbent assay (ELISA) to eliminate the blocking effect of anti-MSLN to CA125 stimulation. Xenograft mouse models were used to detect the effects of CA125 and anti-MSLN on ovarian cancer metastasis in vivo.

Results: DKK1 levels were downregulated in ovarian tumor tissues according to the analyses of two databases and significantly correlated with FIGO stage, grade and disease-free survival in ovarian cancer patients. DKK1 levels were downregulated by CA125 stimulation in vitro. Overexpression of DKK1 reversed the ability of exogenous CA125 to mediate cell migration by activating the SGK3/FOXO3 signaling pathway. Anti-MSLN abrogated the DKK1 reduction and increased the apoptosis of ovarian cancer cells. The use of anti-MSLN in xenograft mouse models significantly reduced tumor growth and metastasis accelerated by CA125.

Conclusions: These experiments revealed that the SGK3/FOXO3 pathway was activated, wherein decreased expression of DKK1 was caused by CA125, which fuels ovarian cancer cell migration. Mesothelin is a potential therapeutic target for the treatment of ovarian cancer metastasis.

Strontium promotes osteogenic differentiation by activating autophagy via the the AMPK/mTOR signaling pathway in MC3T3‑E1 cells

Strontium (Sr) is an alkaline earth metal that exerts the dual effect of improving bone formation and suppressing bone resorption, resulting in increased bone apposition rates and bone mineral density. However, the mechanisms through which Sr exerts these beneficial effects on bone have yet to be fully elucidated. The present study aimed to reveal the underlying molecular mechanisms associated with Sr‑induced osteogenic differentiation. The effects of Sr on cell proliferation and osteogenic differentiation were analyzed by MTT assay, RT‑qPCR, western blot analysis, alkaline phosphatase (ALP) and Alizarin red staining assays. The extent of autophagy was determined by monodansylcadaverine (MDC) staining and western blot analysis of two markers of cellular autophagic activity, the steatosis‑associated protein, sequestosome‑1 (SQSTM1/p62), and the two isoforms of microtubule‑associated protein 1 light chain 3 (LC3), LC‑3‑I/II. The expression levels of AMP‑activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were also detected by western blot analysis. Sr at a concentration of 3 mM exerted the most pronounced effect on osteogenic differentiation, without any apparent cell toxicity. At the same time, cellular autophagy was active during this process. Subsequently, autophagy was blocked by 3‑methyladenine, and the enhancement of osteogenic differentiation in response to Sr was abrogated. Additionally, the phosphorylation level of AMPK was significantly increased, whereas that of mTOR was significantly decreased, in the Sr‑treated group. Taken together, the findings of the present study demonstrate that Sr stimulates AMPK‑activated autophagy to induce the osteogenic differentiation of MC3T3‑E1 cells.

The effect of CA125 on metastasis of ovarian cancer: old marker new function

CA125 has been used extensively to screen for neoplasms, especially in ovarian cancer. The serum CA125 level can be used as a better prognosis evaluation and it may dynamic monitoring the disease progression. We explored the effect of CA125 on ovarian cancer cell migration and its underlying mechanism. Transwell assays showed that exposure to 0.2 μg/ml or 0.4 μg/ml CA125 for 48 h increased migration of A2780 and OVCAR-3 ovarian cancer cells. This effect of CA125 was blocked addition of 200 ng/ml DKK-1, a Wnt pathway inhibitor. Conversely, addition of CA125 reversed the inhibitory effect of Wnt inhibition in A2780 cells pretreated with DKK-1. Examination of CA125 levels in serum from 97 ovarian cancer patients revealed no relationship between a patient's age or CA125 level currently used clinically for ovarian cancer diagnosis and metastasis. However, using receiver operating characteristic (ROC) curves, we identified a new cut-off value for the serum CA125 concentration (82.9 U/ml) that is predictive of metastasis. The area under the curve is 0.632. This new cut-off value has the potential to serve as a clinically useful indicator of metastasis in ovarian cancer patients.

Clinical analysis of lectin-like oxidized low-density lipoprotein receptor-1 in patients with in-stent restenosis after percutaneous coronary intervention

In-stent restenosis (ISR) is the most common complication associated with percutaneous coronary intervention (PCI). Although some studies have reported an association between lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and ISR, not enough clinical validation data are available to support this link. Here, we report our cross-sectional study aimed at exploring the feasibility of LOX-1 as a biomarker for the prognostic diagnosis of patients undergoing PCI.Three groups were included: ISR group, including 99 patients with ISR diagnosed with coronary arteriography (CAG) after PCI; lesion group, comprising 87 patients with coronary artery stenosis (<50%) diagnosed with CAG after PCI; and control group, consisting of 96 volunteers with no coronary artery disease. The levels of LOX-1 were measured in each patient by using an enzyme-linked immunosorbent assay, and their general information as well as laboratory parameters were recorded and followed up during a period of 2 years.LOX-1 levels gradually increased after PCI along with the progression of the lesion in the 3 groups. The levels of LOX-1 were significantly higher in the ISR group than in the other 2 groups (P < .001). LOX-1 levels were correlated with the levels of uric acid (UA) (r = 0.289, P = .007), creatinine (CREA) (r = .316, P = .003), and high-density lipoprotein cholesterol (HDL-C) (r = -0.271, P = .012), whereas no statistically significant correlation was detected with the Gensini score (r = 0.157, P = .141). The sensitivity and specificity of LOX-1 were 81.5% and 55.7%, respectively, with the most optimal threshold (5.04 μg/L). The area under curve (AUC) of the receiver operator characteristic (ROC) curve of LOX-1 was 0.720, and LOX-1 had the highest AUC compared with CREA, UA, and HDL-C, both individually and in combination.A high level of LOX-1 in the early period after PCI has a certain predictive power and diagnostic value for ISR. However, the level of LOX-1 is not related to the Gensini score of coronary artery after PCI, and CREA and UA, which are weakly related to LOX-1, have no obvious synergy in the diagnosis of ISR with LOX-1.

Association of calreticulin expression with disease activity and organ damage in systemic lupus erythematosus patients

Measurement of disease activity in patients with systemic lupus erythematosus (SLE) is important for monitoring disease progression and evaluating the therapeutic effects. The severity of organ damage correlates with clinical status and prognosis. Therefore, it is imperative to find an effective biomarker measuring disease activity and organ damage for SLE management. The present study investigated the possibility of serum calreticulin (CRT) in the assessment of disease activity and organ damage in SLE patients. Serum CRT levels from 80 patients with SLE, 55 patients with other autoimmune diseases and 60 healthy controls (HC) were measured by ELISA. Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores. Organ damage was evaluated with the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. CRT levels in SLE were significantly higher than that in other autoimmune diseases and HC. CRT was correlated with SLEDAI-2K score (r=0.3345, P=0.0024), and with anti-double-stranded DNA (anti-dsDNA) (r=0.4483, P<0.0001). A significant negative correlation of CRT levels with complement 3 (r=-0.3635, P=0.0009) and complement 4 (r=-0.3507, P=0.0014) was observed in patients with SLE. Furthermore, the patients with SLE and a positive anti-Ro52 result had higher levels of CRT compared with those with a negative anti-Ro52 result (P<0.001). Elevated levels of CRT were also reported among patients with SLE who also indicated the presence of cumulative organ damage. In addition, increased expression of CRT correlated with the presence of lupus nephritis. In conclusion, the results of the current report provided that CRT may be used as a potential biomarker for clinical diagnosis and of prognosis, providing additional information regarding disease activity and organ damage alongside other traditional indices.

Synthesis, Characterization, and Biological Evaluation of Nanostructured Hydroxyapatite with Different Dimensions

Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should be considered. In this study, nanosized HA and SrHA with different dimensions and crystallization were synthesized by hydrothermal methods. The phase, crystallization and chemical composition were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The morphology was observed under field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The degradation behaviors of the samples were monitored by determining the ions release profile with inductively coupled plasma mass spectrometry (ICP-MS). The releasing behavior of Ca2+ and Sr2+ showed that the degradation rate was proportional to the specific surface area and inversely proportional to crystallization. The in vitro experiment evaluated by MG63 cells showed that SrHA nanorods with a length greater than 100 nm had the best biological performance both in cell proliferation and differentiation (* p < 0.05 compared with HA-1 and SrHA-1; * p < 0.01 compared with HA-2). In addition, HA nanoparticles with a lower aspect ratio had better bioactivity than higher ones (* p < 0.05). This study demonstrated that nanosized HA and SrHA with subtle differences (including dimensions, crystallization, specific surface area, and degradation rate) could affect the cellular growth and thus might have an impact on bone growth in vivo. This work provides a view of the role of nano-HAs as ideal biocompatible materials in future clinical applications.

Polymerase chain reaction-hybridization method using urease gene sequences for high-throughput Ureaplasma urealyticum and Ureaplasma parvum detection and differentiation

In this article, we discuss the polymerase chain reaction (PCR)-hybridization assay that we developed for high-throughput simultaneous detection and differentiation of Ureaplasma urealyticum and Ureaplasma parvum using one set of primers and two specific DNA probes based on urease gene nucleotide sequence differences. First, U. urealyticum and U. parvum DNA samples were specifically amplified using one set of biotin-labeled primers. Furthermore, amine-modified DNA probes, which can specifically react with U. urealyticum or U. parvum DNA, were covalently immobilized to a DNA-BIND plate surface. The plate was then incubated with the PCR products to facilitate sequence-specific DNA binding. Horseradish peroxidase-streptavidin conjugation and a colorimetric assay were used. Based on the results, the PCR-hybridization assay we developed can specifically differentiate U. urealyticum and U. parvum with high sensitivity (95%) compared with cultivation (72.5%). Hence, this study demonstrates a new method for high-throughput simultaneous differentiation and detection of U. urealyticum and U. parvum with high sensitivity. Based on these observations, the PCR-hybridization assay developed in this study is ideal for detecting and discriminating U. urealyticum and U. parvum in clinical applications.

Synthesis, characterization and biological evaluation of strontium/magnesium-co-substituted hydroxyapatite

The present study aims to investigate the contribution of two biologically important cations, Mg2+ and Sr2+, when co-substituted into the structure of hydroxyapatite (Ca10(PO4)6(OH)2, HA). The substituted samples were synthesized by a hydrothermal method that involved the addition of Mg2+ and Sr2+ containing precursors to partially replace Ca2+ in the apatite structure. Four co-substituted HA samples with different concentrations of Mg2+ and Sr2+ ((Mg + Sr)/(Mg + Sr + Ca) = 30%) were investigated, and they were compared with pure HA. Experimental results showed that only a limited amount of Mg (Mg/(Mg + Ca + Sr) < 14%) could successfully substitute for Ca in HA. In addition, Mg substitution resulted in reduced crystallinity, thermal stability and lattice parameters of HA. In contrast, Sr could fully substitute for Ca. Furthermore, the addition of Sr increased the lattice parameters of HA. Here, we obtained the cation leach liquor by immersing the prepared samples in a culture medium for cell experiments. The in vitro study showed that 10Mg20Sr promoted better MG63 cell attachment, proliferation and differentiation than HA. Thus, the presence of an appropriate proportion of Mg and Sr could play a significant role in the increased biocompatibility of HA.

Effect of siRNA targeting EZH2 on cell viability and apoptosis of bladder cancer T24 cells

We investigated the effect of siRNA targeting enhancer of EZH2 on cell proliferation, invasion, migration, and apoptosis of human bladder cancer T24 cells. An siRNA-expressing plasmid targeting the EZH2 gene was transfected into T24 cells. Quantitative polymerase chain reaction and Western blot analysis were used to detect EZH2 expression at the mRNA and protein levels, respectively. Proliferation, invasion, and migration of T24 cells were examined in vivo using MTT, wound healing, and transwell chamber migration assays, respectively. Annexin V-fluorescein isothiocyanate/propidium iodide flow cytometric analysis was performed to determine cell apoptosis levels. Expression of EZH2 in T24 cells was suppressed at the mRNA and protein levels. Following transfection for 48 h, growth was inhibited by 37.9%, which was markedly lower than that in the negative control group (P < 0.05). Following a wound-healing assay for 24 h, transfected cell migration distance was 1.37 ± 0.12, which was markedly less than the horizontal migration distance of negative control group cells (P < 0.01). In addition, the cell invasion ability of EZH2- siRNA group cells decreased by 67% compared with negative control group cells (P < 0.01). Following transfection for 48 h, early- and late-stage apoptosis rates for T24 cells were 22.8 and 3.60%, respectively, which were higher than in the negative control group (P < 0.01). EZH2 gene silencing effectively suppressed the proliferation, invasion, and migration abilities of human bladder cancer cells, promoting apoptosis.

Microparticle association and heterogeneity of tumor-derived tissue factor in plasma: is it important for coagulation activation?

BACKGROUND

Tumor-derived tissue factor (TF) activates coagulation in vitro and in vivo in an orthotopic model of human pancreatic cancer. Here, we further characterized tumor-derived TF in this model.

METHODS

Conditioned medium (CM) of L3.6pl human pancreatic tumor cells and plasma from nude mice bearing L3.6pl tumors were ultracentrifuged, and the pellets were filtered through membranes with different pore sizes. The size distribution of particles was analyzed in CM or plasma fractions with nanoparticle tracking and dynamic light scattering. Human TF antigen and activity were measured in pellets and supernatants with ELISA and clotting or thrombin generation assays, respectively. Human alternatively spliced TF (asTF) was measured with ELISA. Human TF and thrombin-antithrombin complex (TAT) concentrations were assessed in plasma of mice injected with filtered fractions of CM.

RESULTS

Particles in both CM and plasma were < 0.4 μm. TF antigen and activity in the CM were mainly associated with microparticles (MP). Approximately 50% of antigen and 20% of activity were associated with particles of < 0.1 μm. Injection of < 0.1 μm particles into mice caused a 30% drop in platelet counts and an increase in TAT levels. In contrast, ~ 90% of TF antigen in tumor-bearing mice plasmas was non-sedimentable, whereas TF activity was exclusively associated with MP. Particles of < 0.1 μm and the supernatants of both CM and plasma gained TF activity after addition of exogenous phospholipids. Although asTF was found in MP-free CM supernatants, it was also present in CM and plasma pellets.

CONCLUSIONS

Tumor-derived particles of < 0.1 μm and non-sedimentable TF are or can become procoagulant in the presence of phospholipids, and may contribute to the procoagulant potential of circulating TF.

The diversity of intestinal microbiota of Mongolians living in Inner Mongolia, China

The Mongolian nationality has developed their unique lifestyle and dietary habit for thousands of years. However, by now, little research has been focused on Mongolian gut microbiota and how it is related to different dietary habits. In this study, denaturing gradient gel electrophoresis (DGGE) and quantitative polymerase chain reaction (qPCR) methods were applied to reveal the diversity of predominant gut bacteria of 48 healthy Mongolians recruited from Hohhot city and the Xilin Gol pasturing area in Inner Mongolia. Compared to similar studies of other nationalities, results from the present study have confirmed that the composition of Mongolian gut microbiota is highly similar at the phylum level (Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria) but variable at the genus level. Especially, the numbers of Phascolarctobacterium, Lactobacillus and Bifidobacterium are rather high. DGGE profiles of Lactobacillus and Bifidobacterium revealed that Lactobacillus casei, Bifidobacterium longum and Bifidobacterium animalis subsp. lactis were predominant in the gut of the Mongolian subjects studied. On the contrary, Lactobacillus helveticus was detected in every pasturing area Mongolian, but not in any of the Hohhot city Mongolians. qPCR results revealed that the numbers of Lactobacillus and Bifidobacterium of Xilin Gol Mongolians were significantly higher (P<0.05) than that of Hohhot Mongolians, whereas the numbers of Enterobacterium were significantly lower (P<0.05). In addition, by partial least squares discriminate analysis and cluster analysis of data generated from DGGE and qPCR experiments, a striking difference in the composition of intestinal microbiota of Mongolians living in Hohhot city and the Xilin Gol pasturing area has been found. This study clearly shows that diet affects the microbiota composition of Mongolians living in different circumstances, i.e. urban versus rural.

Small Angle Neutron Scattering Study of the Structure and Formation of Ordered Mesopores in Silica

The nanoscale structure and synthesis mechanisms of a recently developed class of inorganic mesoporous materials with ordered arrays of uniform mesopores have been investigated by small angle neutron scattering (SANS). SANS measurements with solvents imbibed into the pores to vary the scattering contrast demonstrate that the low angle diffraction peaks from these materials are entirely due to the pore structure and that the pores are fully accessible to both aqueous and organic solvents. SANS measurements on the concentrated cationic surfactant and silicate precursor solutions typically used in the synthesis of the mesopore materials indicate that the existence of preassembled supramolecular arrays that mimic the final pore structure is not essential for the synthesis of these materials.

Mesostructure design with gemini surfactants: supercage formation in a three-dimensional hexagonal array

At low temperatures, liquid crystal-like arrays made up of inorganic-cluster and organic molecular units readily undergo reversible lyotropic transformations. Gemini surfactants, with two quaternary ammonium head groups separated by a methylene chain of variable length and with each head group attached to a hydrophobic tail, can be used to control organic charge sitting relative to the bivariable hydrophobic tail configurations. This approach has led to the synthesis of a mesophase (SBA-2) that has three-dimensional hexagonal (P6(3)/mmc) symmetry, regular supercages that can be dimensionally tailored, and a large inner surface area. This mesostructure analog of a zeolite cage structure does not appear to have a lyotropic surfactant or lipid liquid crystal mesophase counterpart. Through the modification of gemini charge separation and each of the two organic tails, these syntheses can be used to optimize templating effects, including the synthesis of MCM-48 at room temperature.

Metal complexation with Langmuir monolayers of histidyl peptide lipids

Langmuir monolayers made from peptide-lipid molecules represent a novel direction in the research areas of biomimetic interfaces and two-dimensional supramolecular chemistry. Peptide structures and molecular recognition activities toward other guest molecules have been the focus of previous study. This study reports the investigation of metal complexation to histidine-containing peptide lipids in the organized Langmuir, Langmuir-Schaefer, or Langmuir-Blodgett films. Three peptide lipids PEP1-PEP3, with a histidine amino acid incorporated in the middle of the peptide, were designed and synthesized. The monolayer structures and metal-binding activities of each peptide lipid and their 1:1:1 molar ratio mixture were studied by thermodynamic and spectroscopic techniques. It was found that hard Lewis acid type metal cations such as K+ and Mg2+, and borderline or soft metal cations such as Zn2+, Cu2+, and Cd2+ exhibit clearly different binding activity toward peptide-lipid monolayers. The conformational changes of peptides upon binding with Cu2+ and Zn2+ were partially revealed by FT-IR spectroscopic studies. Furthermore, by adding a fluorescent-probe lipid to the peptide monolayer, dramatic fluorescence change was observed when Cu2+ or Zn2+ bound to the Langmuir and Langmuir-Schaefer films of peptide-lipid monolayers. Metal-protein complexation plays a crucial role in the function and activity of proteins and enzymes. Investigation of metal complexation to organized peptide Langmuir monolayers may provide an alternative approach for the development of artificial metalloproteins and novel supramolecular systems or materials.

A new fluorescent chemosensor for copper ions based on tripeptide glycyl-histidyl-lysine (GHK)

[structure: see text]. A new fluorescent chemosensor for Cu2+ ions was synthesized by modifying the tripeptide glycyl-histidyl-lysine (GHK) with 9-carbonylanthracene via the standard Fmoc solid-phase peptide synthesis method. While significant fluorescence quenching was observed from the molecule upon binding with Cu2+, addition of Fe2+, Co2+, Ni2+, and Zn2+ to the peptide solution caused a minimum fluorescence emission spectral change, indicating a high specificity of this chemosensor for Cu2+ ions. Effects of pH were also investigated.

[The preparation of collagen burn pellicle of compound sulfadiazine silver and assessment of its efficacy in an animal experiment on deep partial thickness burn wound]

OBJECTIVE

To prepare the collagen burn pellicle of compound sulfadiazine sliver and observe its therapeutic effect on deep partial thickness burn wound.

METHODS

The initator method was adopted for preparing the collagen burn pellicle of compound sulfadiazine sliver. A model of deep partial thickness burn wound was established in 84 SD rats for the observation of the effect of collagen burn pellicle of compound sulfadiazine sliver on burn wound healing.

RESULTS

The collagen burn pellicle of compound sulfadiazine sliver enhanced the coming off of necrotic tissues and the healing of burn wound. The hydroxyproline content of burn wound was higher in the experiment group than that in the comparison groups, (P < 0.05). The percentage of G0/G1-phase in full skin cells of burn wound at 5, 7, 10 and 14 days after burn was lower than that in the comparison groups (P < 0.05). The percentage of S-phase at 5, 7 and 14 days was higher in the experiment group than that in the comparison groups (P < 0.05). The water content in full skin cells of burn wound at 24, 36 and 48 hours after burn was significantly lower in the experiment group than that the comparison groups (P < 0.05).

CONCLUSION

The collagen burn pellicle of compound sulfadiazine sliver can enhance wound healing in the management of deep partial thickness burn wound.

The transport kinetics of lanthanide species in a single erythrocyte probed by confocal laser scanning microscopy

A novel method has been developed to visualize and follow the temporal course of lanthanide transport across the membrane into a single living erythrocyte. By means of confocal scanning microscopy and the optical section technique, the entry of lanthanide ions was followed by the fluorescence quenching of fluorescein isothiocyanate (FITC)-labeled membrane and cytosol. From the difference of the quenching kinetics of the whole section and the central area, the time for diffusion through the membrane and the diffusion in the extracellular and intracellular media can be deduced. To clarify the mechanism of lanthanide-induced fluorescence quenching of FITC-labeled erythrocytes and to ensure that this reaction can be used in this method, the reaction was investigated by steady-state fluorescence techniques. The results showed that the lanthanides strongly quenched the florescence emitted by FITC covalently bound to membrane proteins and cytosolic proteins. The static quenching mechanism is responsible for the fluorescence quenching of FITC-labeled proteins by Ln species. The quenching mechanism is discussed on the basis of complex formation. The dependence of fluorescence quenching on both ion size and the total orbital angular momentum L supports the complexation mechanism. The transport time across the membrane is strikingly correlated with Ln species and extracellular concentration. For a given concentration, the transport time of [Ln(cit)2]3- is much shorter than that of Ln3+, since they enter the cells via the anion channel. This is supported by the inhibition effect of 4,4'-diisothiocyanato-2,2'-stilbenendisulfonate on the transport of [Ln(cit)2]3-. On the other hand, the transport of free Ln3+ might be attributed to the enhanced permeability of erythrocytes owing to Ln3+ binding. These findings strongly demonstrate the existence of the non-internalization mechanism of Ln species uptake by erythrocytes.

Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores

Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce highly ordered, two-dimensional hexagonal (space group p6mm) silica-block copolymer mesophases. Calcination at 500 degrees C gives porous structures with unusually large interlattice d spacings of 74.5 to 320 angstroms between the (100) planes, pore sizes from 46 to 300 angstroms, pore volume fractions up to 0.85, and silica wall thicknesses of 31 to 64 angstroms. SBA-15 can be readily prepared over a wide range of uniform pore sizes and pore wall thicknesses at low temperature (35 degrees to 80 degrees C), using a variety of poly(alkylene oxide) triblock copolymers and by the addition of cosolvent organic molecules. The block copolymer species can be recovered for reuse by solvent extraction with ethanol or removed by heating at 140 degrees C for 3 hours, in both cases, yielding a product that is thermally stable in boiling water.

Oil-Water Interface Templating of Mesoporous Macroscale Structures

Ordered mesostructured porous silicas that are also macroscopically structured were created by control of the interface on two different length scales simultaneously. Micellar arrays controlled the nanometer-scale assembly, and at the static boundary between an aqueous phase and an organic phase, control was achieved on the micrometer to centimeter scale. Acid-prepared mesostructures of silica were made with the p6, Pm3n, and the P63/mmc structures in the form of porous fibers 50 to 1000 micrometers in length, hollow spheres with diameters of 1 to 100 micrometers, and thin sheets up to 10 centimeters in diameter and about 10 to 500 micrometers in thickness. These results might have implications for technical applications, such as slow drug-release systems or membranes, and in biomineralization, where many processes are also interface-controlled.

Cooperative organization of inorganic-surfactant and biomimetic assemblies

A model that makes use of the cooperative organization of inorganic and organic molecular species into three dimensionally structured arrays is generalized for the synthesis of nanocomposite materials. In this model, the properties and structure of a system are determined by dynamic interplay among ion-pair inorganic and organic species, so that different phases can be readily obtained through small variations of controllable synthesis parameters, including mixture composition and temperature. Nucleation, growth, and phase transitions may be directed by the charge density, coordination, and steric requirements of the inorganic and organic species at the interface and not necessarily by a preformed structure. A specific example is presented in which organic molecules in the presence of multiply charged silicate oligomers self-assemble into silicatropic liquid crystals. The organization of these silicate-surfactant mesophases is investigated with and without interfacial silicate condensation to separate the effects of self-assembly from the kinetics of silicate polymerization.

Cooperative Formation of Inorganic-Organic Interfaces in the Synthesis of Silicate Mesostructures

A model is presented to explain the formation and morphologies of surfactant-silicate mesostructures. Three processes are identified: multidentate binding of silicate oligomers to the cationic surfactant, preferential silicate polymerization in the interface region, and charge density matching between the surfactant and the silicate. The model explains present experimental data, including the transformation between lamellar and hexagonal mesophases, and provides a guide for predicting conditions that favor the formation of lamellar, hexagonal, or cubic mesostructures. Model Q(230) proposed by Mariani and his co-workers satisfactorily fits the x-ray data collected on the cubic mesostructure material. This model suggests that the silicate polymer forms a unique infinite silicate sheet sitting on the gyroid minimal surface and separating the surfactant molecules into two disconnected volumes.