Extracellular matrix stiffness mediates radiosensitivity in a 3D nasopharyngeal carcinoma model.

PURPOSE: Radiotherapy is one of the essential treatment modalities for nasopharyngeal carcinoma (NPC), however, radioresistance still poses challenges. Three-dimensional (3D) tumor culture models mimic the in vivo growth conditions of cells more accurately than 2D models. This study is to compare the tumor biological behaviors of NPC cells in 2D, On-Surface 3D and Embedded 3D systems, and to investigate the correlation between radioresistance and extracellular matrix (ECM) stiffness. METHODS: The morphology and radioresistance of the human NPC cell line CNE-1 were observed in 2D and 3D systems. The CCK-8 assay, wounding healing assays, flow cytometry, soft agar assays, and western blot analysis were used to evaluate differences in biological behaviors such as proliferation, migration, cell cycle distribution, and stem cell activity. Different ECM stiffness systems were established by co-blending collagen and alginate in varying proportions. ECM stiffness was evaluated by compressive elastic moduli measurement and colony formation assay was used to assess radioresistance of NPC cells in systems with different ECM stiffness after irradiation. RESULTS: Compared to 2D models, the morphology of NPC cells in 3D culture microenvironments has more in common with in vivo tumor cells and 3D cultured NPC cells exhibit stronger radioresistance. Integrin ß1 but not the epithelial-to-mesenchymal transition pathway in 3D models boost migration ability. Cell proliferation was enhanced, the proportion of tumor stem cells was increased, and G1/S phase arrest occurred in 3D models. NPC cells cultured in softer ECM systems (with low alginate proportions) exhibit striking resistance to ionizing radiation. CONCLUSION: The tumor biological behaviors of NPC cells in 3D groups were obviously different from that of 2D. Radioresistance of NPC cells increased with the stiffness of ECM decreasing.

Combined strategy of knowledge-based rule selection and historical data percentile-based range determination to improve an autoverification system for clinical chemistry test results.

BACKGROUND: Current autoverification, which is only knowledge-based, has low efficiency. Regular historical data analysis may improve autoverification range determination. We attempted to enhance autoverification by selecting autoverification rules by knowledge and ranges from historical data. This new system was compared with the original knowledge-based system. METHODS: New types of rules, extreme values, and consistency checks were added and the autoverification workflow was rearranged to construct a framework. Criteria for creating rules for extreme value ranges, limit checks, consistency checks, and delta checks were determined by analyzing historical Zhongshan laboratory data. The new system's effectiveness was evaluated using pooled data from 20 centers. Efficiency improvement was assessed by a multicenter process. RESULTS: Effectiveness was evaluated by the true positive rate, true negative rate, and overall consistency rate, as compared to manual verification, which were 77.55%, 78.53%, and 78.3%, respectively for the new system. The original overall consistency rate was 56.2%. The new pass rates, indicating efficiency, were increased by 19%-51% among hospitals. Further customization using individualized data increased this rate. CONCLUSIONS: The improved system showed a comparable effectiveness and markedly increased efficiency. This transferable system could be further improved and popularized by utilizing historical data from each hospital.

Designing an Electron-Deficient Pd/NiCo2O4 Bifunctional Electrocatalyst with an Enhanced Hydrodechlorination Activity to Reduce the Consumption of Pd.

Reducing the Pd loading on electrodes is critical in the electrocatalytic hydrodechlorination (EHDC) of chlorinated organic compounds (COCs). The EHDC reaction of COCs on Pd involves three steps: H* formation, H* adsorption, and dechlorination. It has been established that the initial hydrogen evolution reaction (HER) occurs on Pd0 and the dechlorination steps occur on Pd2+. A strategy is proposed to design new electrodes by adding a reducible HER-active interlayer to replace Pd0, fulfilling the responsibility of producing hydrogen, and to facilitate the formation of more Pd2+ for following C-Cl bond cleavage. Keeping the atomic hydrogen adsorption energy on the Pd/interlayer similar to that on pure Pd is also necessary for H* adsorption as well as to maintain a high EHDC activity. For the first time, the NiCo2O4-interlayer-modified Pd/Ni-foam electrode was applied in the EHDC of COCs, which enhanced the EHDC efficiency to 100% within 90 min and reduced 88.6% of Pd consumption. The Pd/NiCo2O4/Ni-foam electrode with enhanced EHDC activity was also observed with almost 100% product selectivity and good stability. A synergistic mechanism is proposed for the enhanced EHDC activity on the Pd/NiCo2O4/Ni-foam. This work offers a simple and useful strategy to design robust electrocatalysts for the EHDC of COCs.

Identification of gene coexpression modules, hub genes, and pathways related to spinal cord injury using integrated bioinformatics methods.

Spinal cord injury (SCI) is characterized by dramatic neurons loss and axonal regeneration suppression. The underlying mechanism associated with SCI-induced immune suppression is still unclear. Weighted gene coexpression network analysis (WGCNA) is now widely applied for the identification of the coexpressed modules, hub genes, and pathways associated with clinic traits of diseases. We performed this study to identify hub genes associated with SCI development. Gene Expression Omnibus (GEO) data sets GSE45006 and GSE20907 were downloaded and the significant correlativity and connectivity between them were detected using WGCNA. Three significant consensus modules, including 567 eigengenes, were identified from the master GSE45006 data following the preconditions of approximate scale-free topology for WGCNA. Further bioinformatics analysis showed these eigengenes were involved in inflammatory and immune responses in SCI. Three hub genes Rac2, Itgb2, and Tyrobp and one pathway "natural killer cell-mediated cytotoxicity" were identified following short time-series expression miner, protein-protein interaction network, and functional enrichment analysis. Gradually upregulated expression patterns of Rac2, Itgb2, and Tyrobp genes at 0, 3, 7, and 14 days after SCI were confirmed based on GSE45006 and GSE20907 data set. Finally, we found that Rac2, Itgb2, and Tyrobp genes might take crucial roles in SCI development through the "natural killer cell-mediated cytotoxicity" pathway.

Dispersed copper nanoparticles promote the electron mobility of nitrogen-rich graphitized carbon aerogel for electrochemical determination of 4-nitrophenol.

An electrochemical method was designed for the determination and simultaneous reduction of 4-nitrophenol (4-NP). A nitrogen-rich carbon aerogel was synthesized from the precursor of phenol, formaldehyde and melamine. Then, copper nanoparticles were embedded into the aerogel, and the resulting material was used to modify a glassy carbon electrode (GCE), which displayed excellent electrocatalytic activity. Sensitive determination of 4-NP by cyclic voltammetry in 0.5 M sulfuric acid was accomplished. Among the various compositions of Cux@NC, the electrode modified with Cu3@NC showed the strongest reduction peak, typically at a potential of -0.30 V vs. reversible hydrogen electrode (RHE). A further study shows the cyclic voltammetry potential range to extend from -0.46 to +0.44 V (vs. RHE) at a scan rate of 100 mV s-1. Differential pulse voltammetric determination of 4-NP gave a lower detection limit of 53 nM and a current sensitivity of 0.7 µA µM-1 cm-2. The method was applied to the determination of 4-NP in spiked water samples, with comparable results of HPLC. The excellent performance was attributed to the highly graphitized structure of the aerogel with its large surface area and small pore size, and the presence of Cu-N structures as active sites. Graphical abstractSchematic representation of electrochemical determination and reduction of 4-nitrophenol under the glassy carbon electrode modified with highly dispersed Cu nanoparticles embedded on nitrogen-rich carbon aerogel. W: working electrode; R: reference electrode; C: counter electrode). Left: copper nanoparticles embedded in an aerogel.

Characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age: a hospital-based cross-sectional study.

BACKGROUND: Acute diarrhea is a leading cause of morbidity and mortality in children, particularly in those under the age of 5 years. Rotavirus is recognized as the leading cause of acute diarrhea in children, however, the contribution of bacterial pathogens as causative agents varies throughout the world. Here we report a hospital-based prospective study to analyze the characteristics of bacterial pathogens associated with acute diarrhea in children under 5 years of age. METHODS: Stool samples were collected from 508 patients with acute diarrhea under 5 years of age who presented at our hospital. Nine pathogens were isolated and identified by culturing, serology or PCR, these included Salmonella spp., Shigella spp., Vibrio cholerae, diarrheagenic Escherichia coli (DEC), Aeromonas spp., Plesiomonas spp., Vibrio parahaemolyticus, Campylobacter spp. and Yersinia enterocolitica. Antimicrobial sensitivity tests of these pathogens were conducted. The most commonly detected pathogen, Salmonella spp., was further investigated by PCR and sequencing of antibiotic resistance-related genes. RESULTS: Pathogens were identified in 20.1 % of the 508 samples. The most commonly detected pathogens were Salmonella spp. (8.5 %), followed by DEC (4.7 %), Campylobacter jejuni (3.0 %) and Aeromonas spp. (2.0 %). The resistance rates to ampicillin and tetracycline in Salmonella spp. were >60 %, but were <30 % to cephalosporins and quinolones. More than 50 % of DEC strains displayed resistance to ampicillin, cefotaxime and tetracycline, and 60 % of C. jejuni strains were resistant to ciprofloxacin but highly sensitive to the other antibiotics. Among 12 cephalosporin-resistant Salmonella isolates, TEM-1 and CTX-M-14 determinants were present in two (16.7 %) isolates. PCR screening for plasmid-mediated quinolone resistance genes revealed gyrA mutations in one of three highly quinolone resistant isolates. CONCLUSIONS: Salmonella spp., DEC, Campylobacter spp. and Aeromonas spp. were the most commonly detected bacterial pathogens in children under the age of 5 years with acute diarrhea. Our findings indicate that ampicillin and tetracycline are not suitable as first line therapeutic drugs against Salmonella spp. Resistance to third generation cephalosporins and quinolones was also detected. TEM-1 and CTX-M-14 genetic determinants, and gyrA mutations, were the major mechanisms associated with high levels of cephalosporin and quinolone resistance, respectively, in Salmonella isolates.

CO2 Hydrogenation over Oxide-Supported PtCo Catalysts: The Role of the Oxide Support in Determining the Product Selectivity.

By simply changing the oxide support, the selectivity of a metal-oxide catalysts can be tuned. For the CO2 hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO2 , ZrO2 , and TiO2 ), replacing a TiO2 support by CeO2 or ZrO2 selectively strengthens the binding of C,O-bound and O-bound species at the PtCo-oxide interface, leading to a different product selectivity. These results reveal mechanistic insights into how the catalytic performance of metal-oxide catalysts can be fine-tuned.

Growth and production of microencapsulated recombinant CHO in a stirred tank bioreactor.

Microencapsulation supplies cells with a three-dimensional microenvironment enhancing the metabolic activity, cell density and recombinant protein expression in a stirred tank bioreactor which is used widely to culture mammalian cells in many biochemical processes. In this paper, we address the growth and Desmodus rotundus salivary plasminogen activator (DSPA) production of recombinant CHO (rCHO) in a stirred tank bioreactor. Cells were cultured using two different methods--in an unmicroencapsulated versus microencapsulated culture--and compared differences between them in terms of cell reproduction and DSPA protein productivity. Compared to the unmicroencapsulated rCHO, microencapsulated cells got higher cell density and prolonged the plateau phase. Microencapsulated rCHO promoted DSPA production, with a maximum rate that was 4.8 times higher than in unmicroencapsulated cells, and the accumulated production of DSPA was 3.3 higher than in unmicroencapsulated cells. Negative relationship was found between specific growth rate and DSPA production capacity of unit cells. These findings will facilitate the methods for higher DSPA production in stirred tank bioreactors.

[Effect of microencapsulation on the expression of the oxidative stress genes of HepG2 cells and exogenous regulation].

The aim of this research is to investigate the influence of microencapsulation on the expression of the oxidative stress genes and exogenous regulation of HepG2 cells. We compared the expression of hemeoxygenase-1 (HO-1) and glutathione S-transferases-A1 (GST-A1) in HepG2 cells under different culture conditions through real-time PCR. The effects of exogenous antioxidants on cell viability and albumin levels were also evaluated through MTT assay and ELISA assay. The results showed that after culturing for 6 and 16 days, the expression levels of HO-1 in encapsulated cells were approximately 4.9 and 3.1 times higher than that of monolayer cells at the same culture period; As for the expression levels of GST-A1, they were elevated to 11.2 and 33 times of monolayer cells (P < 0.05). Accordingly, we found that NAC at 5-10 mmol/L significantly increased the viability by 40%-70% and the biosynthetic function by 20%-30% in microencapsulated HepG2 cells (P < 0.05). GSH increased the viability of the encapsulated cells by 20%-55% and the biosynthetic function by 15% (P < 0.05). In conclusion, oxidative stress exists in the microcapsules and affects genes expression. Exogenous antioxidants can prevent the inhibition effects of oxidative stress on cellular growth.

Coupling Fe-Co atomic pair to promote the selective reduction of nitroaromatics under mild conditions.

Selectively reducing nitroaromatics into aromatic amines will not only remove nitroaromatic pollutants in waste effluents to reduce environmental risks, but also yield important feedstocks for chemical industrial manufactures. In this study, a FeCo-co-embedded N-doped Carbon (FeCo-N-C) catalyst with Fe-Co atomic pair has been identified with favorable activity, superior selectivity, excellent reusability, as well as outstanding performance in the treatment of real water. The combined results from theoretical study and experimental tests indicate that the improved catalytic performance of FeCo-N-C is owing to the narrowed band gap and electron delocalization caused by the Fe-Co atomic pair which can improve electron transport in its catalytic reaction. The results of isotope experiments and H* quenching experiments confirm that H2O is the source of hydrogen in catalytic reduction of PNP. FeCo-N-C is identified as a superior catalyst to replace multitudinous currently used noble-metal catalysts for the selective catalytic reduction of nitroaromatics in wastewater treatment.

Patient-derived organoid elucidates the identical clonal origin of bilateral breast cancer with diverse molecular subtypes.

Bilateral breast cancer (BBC), an infrequent breast cancer subtype, has primarily been studied in terms of incidence, prognosis, and through comparative analysis of synchronous (SBBC) and metachronous (MBBC) manifestations. The advent and application of organoid technology hold profound implications for tumor research and clinical management. This study represents the pioneering use of organoid models in BBC research. We established organoid lines from two surgical tumor specimens of a BBC patient, with one line undergoing detailed pathological and genomic analysis. The BBC organoid from the right breast demonstrated a marker expression profile of ER (-), PR (-), HER-2 (0), and Ki67 index 10%, indicating that it may derived from the TNBC tissue. Whole Exome Sequencing (WES) displayed consistent set of Top10 cancer driver genes affected by missense mutations, frameshift mutation, or splice site mutations in three tumor tissues and the organoid samples. The organoids' single nucleotide polymorphisms (SNPs) were more closely aligned with the TNBC tissue than other tumor tissues. Evolutionary analysis suggested that different tumor regions might evolve from a common ancestral layer. In this case, the development of BBC organoids indicated that simultaneous lesions with diverse molecular profiles shared a high degree of consistency in key tumor-driving mutations. These findings suggest the feasibility of generating BBC organoids representing various molecular types, accurately replicating significant markers and driver mutations of the originating tumor. Consequently, organoids serve as a valuable in vitro model for exploring treatment strategies and elucidating the underlying mechanisms of BBC.

The effect of electrostatic microencapsulation process on biological properties of tumour cells.

Microencapsulation is one of the promising strategies to develop a three-dimensional in vivo tumour-mimic model in cancer research. Although previous studies have shown that tumour cells grow well during the microencapsulated culture, it is still not clear whether the electrostatic encapsulation process has an important effect on cellular characteristics. In this study, we investigated cellular response against non-physiological stress factors existing in the electrostatic microencapsulation process, such as the high-voltage electrostatic field, suspension and nutrition-free status. Our results showed that these non-physiological stress factors did not significantly induce cellular apoptosis, and did not affect cellular adhesion and viability. Furthermore, no change was found about invasion and drug resistance of the tumour cells. The normal endoplasmic reticulum function might play a role in maintaining biological properties during the electrostatic microencapsulation process.

Enhanced quorum sensing capacity via regulating microenvironment to facilitate stress resistance of probiotic in alginate-based microcapsules.

Alginate-based microcapsule has becoming a promising carrier for probiotic encapsulation due to the improved stress resistant ability. Besides the physical protection of microcapsules, bacterial quorum sensing (QS) is another prominent factor affecting microbial stress resistance in microcapsules. In the present study, Vibrio harveyi cells were entrapped and proliferated into cell aggregates in alginate-based microcapsules. The microenvironment composed of cells and biomacromolecules was regulated by the diameter, alginate concentration and core state of microcapsule. Then the effect of microenvironment on bacterial QS capacity was investigated, including bioluminescence, autoinducers (AIs) production and QS related genes expression. The highest diameter of 1200 µm and highest alginate concentration of 2.0 % w/v under the investigation range presented strongest QS capacity, and the maintenance of hydrogel core could enhance bacterial QS. Moreover, the mechanism analysis revealed that the formed biofilm on the surface of cell aggregates hampered the outward transfer of AIs, and the local AIs inside the cell aggregates induced stronger bacteria QS by close-range interaction. As a whole, these findings are helpful to guide the technological development and optimization of microencapsulated probiotics with stronger stress resistance, and the potential application in food, dairy, wastewater treatment and biosensor.

Coupling Ni-Cu atomic pair to promote CO2 electroreduction with near-unity CO selectivity.

The electrocatalytic reduction of CO2 towards CO is one of the most desirable routines to reduce atmospheric CO2 concentration and maintain a global carbon balance. In this work, a novel porous NiCu-embedded ZIF-derived N-doped carbon nanoparticle (NiCu@NCNPs) catalyst has been identified as an active, highly selective, stable, and cost-effective catalyst in CO2 reduction. A CO selectivity as high as 100% has been achieved on NiCu@NCNPs which is the highest reported to date. The particle current density of CO on NiCu@NCNPs is around 15 mA cm-2 under the optimized potential at -0.9 V vs. RHE. The NiCu@NCNPs electrode also exhibits excellent stability during the five sequential CO2 electroreduction experiments. The superior catalytic performance of NiCu@NCNPs in CO2RR can be related to its microstructure with high electrochemical surface area and low electron transfer resistance. Furthermore, a kinetic analysis has shown the formation of intermediate *COOH is the rate-determining step in CO2RR towards CO. According to the results of density functional theory (DFT) calculations, a low Gibbs-free energy change (∆G) for the rate-determining step leads to the enhanced catalytic performance of CO2RR on NiCu@NCNPs.

Effect of the uronic acid composition of alginate in alginate/collagen hybrid hydrogel on chondrocyte behavior.

Introduction: Developing a culture system that can effectively maintain chondrocyte phenotype and functionalization is a promising strategy for cartilage repair. Methods: An alginate/collagen (ALG/COL) hybrid hydrogel using different guluronate/mannuronate acid ratio (G/M ratio) of alginates (a G/M ratio of 64/36 and a G/M ratio of 34/66) with collagen was developed. The effects of G/M ratios on the properties of hydrogels and their effects on the chondrocytes behaviors were evaluated. Results: The results showed that the mechanical stiffness of the hydrogel was significantly affected by the G/M ratios of alginate. Chondrocytes cultured on Mid-G/M hydrogels exhibited better viability and phenotype preservation. Moreover, RT-qPCR analysis showed that the expression of cartilage-specific genes, including SOX9, COL2, and aggrecan was increased while the expression of RAC and ROCK1 was decreased in chondrocytes cultured on Mid-G/M hydrogels. Conclusion: These findings demonstrated that Mid-G/M hydrogels provided suitable matrix conditions for cultivating chondrocytes and may be useful in cartilage tissue engineering. More importantly, the results indicated the importance of taking alginate G/M ratios into account when designing alginate-based composite materials for cartilage tissue engineering.

Enhancement of surface graft density of MPEG on alginate/chitosan hydrogel microcapsules for protein repellency.

Alginate/chitosan/alginate (ACA) hydrogel microcapsules were modified with methoxy poly(ethylene glycol) (MPEG) to improve protein repellency and biocompatibility. Increased MPEG surface graft density (n(S)) on hydrogel microcapsules was achieved by controlling the grafting parameters including the buffer layer substrate, membrane thickness, and grafting method. X-ray photoelectron spectroscopy (XPS) model was employed to quantitatively analyze n(S) on this three-dimensional (3D) hydrogel network structure. Our results indicated that neutralizing with alginate, increasing membrane thickness, and in situ covalent grafting could increase n(S) effectively. ACAC(PEG) was more promising than ACC(PEG) in protein repellency because alginate supplied more -COO(-) negative binding sites and prevented MPEG from diffusing. The n(S) increased with membrane thickness, showing better protein repellency. Moreover, the in situ covalent grafting provided an effective way to enhance n(S), and 1.00 ± 0.03 chains/nm(2) was achieved, exhibiting almost complete immunity to protein adsorption. This antifouling hydrogel biomaterial is expected to be useful in transplantation in vivo.

Highly selective electrocatalytic reduction of CO2 to HCOOH over an in situ derived hydrocerussite thin film on a Pb substrate.

A metal oxide electrode has been developed for the electrochemical CO2 reduction reaction (eCO2RR). It exhibits superior activity and product selectivity towards eCO2RR by circumventing the previously encountered problem of self-reduction with high-valence metals. Specifically, a hydrocerussite [Pb3(CO3)2(OH)2] thin film has been synthesized in situ on a Pb substrate (denoted as ER-HC) by an electroreduction method using a lead-based metal-organic framework (Pb-MOF) as a precursor. The ER-HC electrode exhibits a high selectivity of 96.8% towards HCOOH production with a partial current density of 1.9 mA cm-2 at -0.88 V vs. the reversible hydrogen electrode (RHE). A higher HCOOH partial current density of 7.3 mA cm-2 has been achieved at -0.98 V vs. RHE. Physicochemical and electrochemical characterization results demonstrate that the defective hydrocerussite surface exhibits appropriate adsorption free energy of formate (HCOO-) and a lower reaction free energy for HCOOH production from CO2, which greatly boosts the eCO2RR activity and HCOOH production selectivity. The structure and eCO2RR performance of the hydrocerussite thin film remain stable in 0.1 M KHCO3 as electrolyte, ensuring its durability. Overall, this work not only provides a metal oxide electrode (metal hydroxide, to be more precise) with excellent eCO2RR performance, but also expands the in situ electrochemical derivatization strategy for the fabrication of metal oxide electrodes.

Glycolaldehyde as a probe molecule for biomass derivatives: reaction of C-OH and C═O functional groups on monolayer Ni surfaces.

Controlling the activity and selectivity of converting biomass derivatives to syngas (H(2) and CO) is critical for the utilization of biomass feedstocks as renewable sources for chemicals and fuels. One key chemistry in the conversion is the selective bond scission of the C-OH and C═O functionalities, which are present in many biomass derivatives. Because of the high molecular weight and low vapor pressure, it is relatively difficult to perform fundamental surface science studies of C6 sugars, such as glucose and fructose, using ultrahigh vacuum techniques. Glycolaldehyde (HOCH(2)CH═O) is the smallest molecule that contains both the C-OH and C═O functional groups, as well as the same C/O ratio as C6 sugars, and thus is selected as a probe molecule in the current study to determine how the presence of the C═O bond affects the reaction mechanism. Using a combination of density functional theory calculations and experimental measurements, our results indicate that the reaction pathway of glycolaldehyde to produce syngas can be enhanced by supporting monolayer Ni on a Pt substrate, which shows higher activity than either of the parent metals. Furthermore, the Pt substrate can be replaced by tungsten monocarbide to achieve similar activity and selectivity, indicating the possibility of using Ni/WC to replace Ni/Pt as active and selective catalysts with higher stability and lower cost.

Differentiation of O-H and C-H bond scission mechanisms of ethylene glycol on Pt and Ni/Pt using theory and isotopic labeling experiments.

Understanding and controlling bond-breaking sequences of oxygenates on transition metal catalysts can greatly impact the utilization of biomass feedstocks for fuels and chemicals. The decomposition of ethylene glycol, as the simplest representative of biomass-derived polyols, was studied via density functional theory (DFT) calculations to identify the differences in reaction pathways between Pt and the more active Ni/Pt bimetallic catalyst. Comparison of the computed transition states indicated three potentially feasible paths from ethylene glycol to C1 oxygenated adsorbates on Pt. While not important on Pt, the pathway to 1,2-dioxyethylene (OCH(2)CH(2)O) is favored energetically on the Ni/Pt catalyst. Temperature-programmed desorption (TPD) experiments were conducted with deuterated ethylene glycols for comparison with DFT results. These experiments confirmed that decomposition of ethylene glycol on Pt proceeds via initial O-H bond cleavage, followed by C-H and the second O-H bond cleavages, whereas on the Ni/Pt surface, both O-H bonds are cleaved initially. The results are consistent with vibrational spectra and indicate that tuning of the catalyst surface can selectively control bond breaking. Finally, the significant mechanistic differences in decomposition of polyols compared to that of monoalcohols and hydrocarbons serve to identify general trends in bond scission sequences.

Preparation of Cationic Amphiphilic Nanoparticles with Modified Chitosan Derivatives for Doxorubicin Delivery.

Polymeric micelle-like nanoparticles have demonstrated effectiveness for the delivery of some poorly soluble or hydrophobic anticancer drugs. In this study, a hydrophobic moiety, deoxycholic acid (DCA) was first bonded on a polysaccharide, chitosan (CS), for the preparation of amphiphilic chitosan (CS-DCA), which was further modified with a cationic glycidyltrimethylammounium chloride (GTMAC) to form a novel soluble chitosan derivative (HT-CS-DCA). The cationic amphiphilic HT-CS-DCA was easily self-assembled to micelle-like nanoparticles about 200 nm with narrow size distribution (PDI 0.08-0.18). The zeta potential of nanoparticles was in the range of 14 to 24 mV, indicating higher positive charges. Then, doxorubicin (DOX), an anticancer drug with poor solubility, was entrapped into HT-CS-DCA nanoparticles. The DOX release test was performed in PBS (pH 7.4) at 37 °C, and the results showed that there was no significant burst release in the first two hours, and the cumulative release increased steadily and slowly in the following hours. HT-CS-DCA nanoparticles loaded with DOX could easily enter into MCF-7 cells, as observed by a confocal microscope. As a result, DOX-loaded HT-CS-DCA nanoparticles demonstrated a significant inhibition activity on MCF-7 growth without obvious cellular toxicity in comparison with blank nanoparticles. Therefore, the anticancer efficacy of these cationic HT-CS-DCA nanoparticles showed great promise for the delivery of DOX in cancer therapy.