Nuttaporn Pimpha

Development of Gelatin Hydrogel Pads as Antibacterial Wound Dressings

Gelatin hydrogel pads have been prepared from a 10 wt.-% gelatin solution that contained 2.5 wt.-% AgNO(3) in 70% v/v acetic acid by a solvent-casting technique. The AgNO(3)-containing gelatin solution was aged under mechanical stirring for various time intervals to allow for the formation of silver nanoparticles (nAgs). The formation of nAgs was monitored by a UV-vis spectrophotometer. The morphology and size of the nAgs were characterized by transmission electron microscopy (TEM). To improve the water resistance of the hydrogels, various contents of glutaraldehyde (GTA) were added to the AgNO(3)-containing gelatin solution to cross-link the obtained gelatin hydrogels. These hydrogels were tested for their water retention and weight loss behavior, release characteristics of the as-loaded silver, and antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The AgNO(3)-containing gelatin solution that had been aged for 5 d showed the greatest number of nAgs formed. The size of these particles, based on TEM results, was 10-11 nm. With an increase in the GTA content used to cross-link the hydrogels, the water retention, the weight loss, and the cumulative amount of silver released were found to decrease. Finally, all of the nAg-loaded gelatin hydrogels could inhibit the growth of the tested pathogens, which confirmed their applicability as antibacterial wound dressings.

Synthesis of poly(methyl methacrylate) core/chitosan-mixed-polyethyleneimine shell nanoparticles and their antibacterial property.

The core-shell nanoparticles possessing poly(methyl methacrylate) (PMMA) core coated with chitosan (CS), polyethyleneimine (PEI), and chitosan-mixed-polyethyleneimine (CS/PEI) shells were synthesized in this work. The emulsifier-free emulsion polymerization triggered by a redox initiating system from t-butylhydroperoxide (TBHP) and amine groups on CS and/or PEI was used as a synthetic method. In the CS/PEI systems, the amount of CS was kept constant (0.5g), while the amount of PEI was varied from 0.1 to 0.5g. The surface and physico-chemical properties of prepared nanoparticles were then examined. FTIR spectra indicated the presence of grafted PMMA on CS and/or PEI, and the weight fraction of incorporated PEI in the CS/PEI nanoparticles. All nanoparticles were spherical in shape with uniform size distribution illustrated by scanning electron microscopy (SEM). The introduction of PEI to CS nanoparticles yielded the higher monomer conversion, grafting efficiency, and grafting percentage compared with the CS nanoparticles. The size of CS/PEI nanoparticles was smaller than the original CS and PEI nanoparticles, and tended to decrease with increasing amount of PEI introduced. The introduction of PEI also brought the higher colloidal stability to the nanoparticles as indicated by zeta-potential measurement and isoelectric point analysis. The nanoparticles exhibited a promising antibacterial activity against Staphylococcus aureus and Escherichia coli. The nanoparticle-bacteria interaction was studied via SEM. The results suggested that they would be useful as effective antibacterial agents.

Gene Delivery Efficacy of Polyethyleneimine-Introduced Chitosan Shell/Poly(methyl Methacrylate) Core Nanoparticles for Rat Mesenchymal Stem Cells

This work investigated polyethyleneimine (PEI)-introduced chitosan (CS) (CS/PEI) nanoparticles as non-viral carrier of plasmid DNA for rat mesenchymal stem cells (MSCs). The CS/PEI nanoparticles were prepared by the emulsifier-free emulsion polymerization of methyl methacrylate monomer induced by a small amount of t-butyl hydroperxide in the presence of different concentrations of PEI mixed with CS. The resulting nanoparticles were characterized by their surface properties and buffering capacity. In vitro gene transfection was also evaluated. The introduction of PEI affected the surface charge, dispersing stability and buffering capacity of the nanoparticles. The CS/PEI nanoparticles formed a complex upon mixing with a plasmid DNA of luciferase. The complex enhanced the level of gene transfection and prolonged the time period of expression for MSCs, compared with those of plasmid DNA–original CS and PEI nanoparticles. Cytotoxicity of CS/PEI complexes with plasmid DNA was significantly low, depending on the amount of PEI introduced. It is concluded that the CS/PEI nanoparticle was a promising carrier for gene delivery of MSCs.

Self-aggregates formation and mucoadhesive property of water-soluble β-cyclodextrin grafted with chitosan.

Water-soluble β-cyclodextrin grafted with chitosan (CD-g-CS) was carried out by quaternizing the CD-g-CS with glycidyltrimethyl ammonium chloride (GTMAC) under mild acidic condition, corresponding to the quaternized CD-g-CS (QCD-g-CS). The degrees of substitution (DS) and quaternization (DQ), ranging from 5% to 23% and 66% to 80%, respectively, were determined by (1)H NMR spectroscopy. Self-aggregates formation of all QCD-g-CSs were investigated in water using dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques. The result revealed that all QCD-g-CSs are able to form self-aggregates in water. Large particle sizes ranged from 800 to 3000nm were obtained by DLS while zeta-potentials were ranging from 25 to 40mV. AFM and TEM depicted a spherical shape with particle sizes ranging from 100 to 900nm. Mucoadhesive and cytotoxic properties of all QCD-g-CSs were evaluated using a mucin particle method and MTT assay compared to quaternized chitosan (QCS). It was found that the mucoadhesive property increased with decreasing DS due to less quaternary ammonium moiety into the chitosan backbone. On the other hand, the cytotoxicity increased with increasing DS even though the DQ is decreased.

The PEI-introduced CS shell/PMMA core nanoparticle for silencing the expression of E6/E7 oncogenes in human cervical cells.

In this study, we examined the potential of cationic nanoparticle - polyethyleneimine-introduced chitosan shell/poly (methyl methacrylate) core nanoparticles (CS-PEI) for siRNA delivery. Initially, DNA delivery was performed to validate the capability of CS-PEI for gene delivery in the human cervical cancer cell line, SiHa. siRNA delivery were subsequently carried out to evaluate the silencing effect on targeted E6 and E7 oncogenes. Physicochemical properties including size, zeta potential and morphology of CS-PEI/DNA and CS-PEI/siRNA complexes, were analyzed. The surface charges and sizes of the complexes were observed at different N/P ratios. The hydrodynamic sizes of the CS-PEI/DNA and CS-PEI/siRNA were approximately 300-400 and 400-500nm, respectively. Complexes were positively charged depending on the amount of added CS-PEI. AFM images revealed the mono-dispersed and spherical shapes of the complexes. Gel retardation assay confirmed that CS-PEI nanoparticles completely formed complexes with DNA and siRNA at a N/P ratio of 1.6. For DNA transfection, CS-PEI provided the highest transfection result. Localization of siRNA delivered through CS-PEI was confirmed by differential interference contrast (DIC) confocal imaging. The silencing effect of siRNA specific to HPV 16 E6/E7 oncogene was examined at 18 and 24h post-transfection. The results demonstrated the capacity of CS-PEI to suppress the expression of HVP oncogenes.

Preparation of anti-CD4 monoclonal antibody-conjugated magnetic poly(glycidyl methacrylate) particles and their application on CD4+ lymphocyte separation

Novel immunomagnetic particles have been prepared for separation of CD4(+) lymphocytes. The magnetic nanoparticles with a diameter of approximately 5-6 nm were first synthesized by co-precipitation from ferrous and ferric iron solutions and subsequently encapsulated with poly(glycidyl methacrylate) (PGMA) by precipitation polymerization. Monoclonal antibody specific to CD4 molecules expressed on CD4(+) lymphocytes was conjugated to the surface of magnetic PGMA particles through covalent bonding between epoxide functional groups on the particle surface and primary amine groups of the antibodies. The generated immunomagnetic particles have successfully separated CD4(+) lymphocytes from whole blood with over 95% purity. The results indicated that these particles can be employed for cell separation and provide a strong potential to be applied in various biomedical applications including diagnosis, and monitoring of human diseases.

A comparison of spacer on water-soluble cyclodextrin grafted chitosan inclusion complex as carrier of eugenol to mucosae

In this study two types of water-soluble βCD grafted chitosan were synthesized and compared based on similar degree of N-substitution of βCD moiety; QCD23-g-CS contained methylene spacer and QCDCA22-g-CS contained citric acid spacer. The QCD23-g-CS demonstrated greater eugenol (EG) encapsulation efficiency than that of QCDCA22-g-CS. The micelle-like assemblies of QCD23-g-CS led to slower release of EG while it did not observe in case of QCDCA22-g-CS. It was found that EG could absorb on chitosan backbone according to in silico modeling. Cytotoxicity of both derivatives against buccal mucosa cell is concentration-dependent. The QCDCA22-g-CS demonstrated stronger mucoadhesive response than that of QCD23-g-CS, due to hydrogen bonding according to mucin particle and SPR methods. Our results revealed that the spacer on both derivatives played an important role on binding affinity with EG, releasing profile and mucoadhesive property. These derivatives could be considered as promising carriers for mucosal delivery system.

Gold nanoparticle as an alternative tool for a urine pregnancy test.

OBJECTIVE The urine pregnancy test is an easily available diagnostic test in the present day and is routinely performed. The test is based on an immunochromatography technique. Here, we used an advanced nanomedicine technique for modification of the urine pregnancy test. MATERIALS AND METHODS The preparation of gold nanoparticle solution in this study followed the standard method. We performed an experiment on both pregnancy-positive and -negative urine samples. First, a mixture with an equal amount (500 microliters) of gold nanoparticle solution and urine sample was prepared. Then, it was further tested for pregnancy by the urine pregnancy test strip. RESULTS The pregnancy-positive mixture became pink, while the pregnancy-negative mixture became gray. The urine pregnancy test strip for a positive mixture had two lines, while the negative mixture had one line. CONCLUSION This application can help the diagnosis of pregnancy and can be an alternative method for a urine pregnancy test. To our knowledge, this is the first report on this application.

Polyethylenimine-immobilized core–shell nanoparticles: Synthesis, characterization, and biocompatibility test

Herein, we prepared PEI-immobilized core-shell particles possessing various types of polymer cores via a visible light-induced surfactant-free emulsion polymerization (SFEP) of three vinyl monomers: styrene (St), methyl methacrylate (MMA), and 2-hydroxyethyl methacrylate (HEMA). An effect of monomers on the polymerization and characteristics of resulting products was investigated. Monomers with high polarity can provide high monomer conversion, high percentage of grafted PEI, stable particles with uniform size distribution but less amino groups per particles. All prepared nanoparticles exhibited a core-shell nanostructure, containing PEI on the shell with hydrodynamic size around 140-230nm. For in-vitro study in Caco-2 cells, we found that the incorporation of PEI into these core-shell nanoparticles can significantly reduce its cytotoxic effect and also be able to internalized within the cells. Accordingly, these biocompatible particles would be useful for various biomedical applications, including gene transfection and intracellular drug delivery.

Photocatalytic degradation of 2,4-dichlorophenol over Fe-ZnO catalyst under visible light

Fe-ZnO was synthesized via impregnation and applied to photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) under visible light. Conditions of Fe-ZnO synthesis which included a Fe content and a calcination temperature were focused. From UV-DRS, visible light absorption of Fe-ZnO samples increased with increasing of Fe content and calcination temperature. TEM images revealed Fe species (FeO, Fe3O4, and Fe2O3) on ZnO as a function of calcination temperature. XANES analysis confirmed the majority of Fe3+ content. Response surface methodology (RSM) dominating over experimental design and statistical analysis for 2,4-DCP photocatalytic degradation indicated that the high degradation efficiency was associated with calcination temperature of 680–700 °C, Fe content of 4.5–5.0 mol%, and catalyst loading of 1.2–1.8 g L−1. Moreover, addition of 2mM of K2S2O8 in a 5.0Fe-ZnO@700 °C system could enhance the degradation efficiency to a completion within 90 min. The kinetics of 2,4-DCP photocatalytic degradation well fit the Langmuir-Hinshelwood model.