Knowledge and attitude toward oral health behavior of overseas students during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic has impacted overseas students, including their oral health. Due to movement restrictions, limited living allowances, dental treatment costs, and health insurance fees, overseas students might be more concerned about their oral health. The objective of the present study was to determine the association of knowledge and attitude toward oral healthcare behavior of overseas university students staying in Thailand between January 2020 to July 2022 and explore the experiences of their oral health problems. METHODS: A cross-sectional study was conducted using an online survey in English operated through the Google platform by convenience sampling among overseas Chulalongkorn University students. A newly developed self-administered questionnaire on knowledge and attitude toward oral health-related behavior and experiences in oral health problems was completed voluntarily. Descriptive statistics, Chi-square test, t-test, ANOVA, and Pearson correlations were employed using IBM SPSS version 29. RESULTS: Of 311 overseas students, 55.6% were male. The average age of students was 27.5 ± 4.5 years. 68.81% of students were from ASEAN countries, and 73.31% studied in non-health science programs. The study fields, health and non-health sciences, were associated with knowledge score (p < 0.001) and attitude score (p = 0.004), whereas the type of health insurance had an association with behavior score (p = 0.014) and the student's perspective about dental visits (p = 0.014). Three hundred fifty-nine cases of oral health problems were experienced by 47.3% of overseas students. These problems consisted primarily of tooth hypersensitivity (21.2%), gingivitis (15.3%), caries (14%), cracked or broken tooth (10%), severe toothache (9%), fallen out filling (8%), and wisdom tooth pain (7.8%). There was an association between oral healthcare behavior and oral health problems (p < 0.001), and a negative correlation was found between behavior score and the number of oral health problems (p < 0.001, r=-0.204). CONCLUSION: The oral healthcare habits of overseas university students correlated positively with knowledge and attitude. A negative correlation was observed between behavior and the number of oral health problems. Furthermore, studying in health science programs impacted students' knowledge and attitude toward oral health, while dental treatment coverage insurance affected decisions for dental visits.

Multifunctional cellulosic nanofiber film with enhanced antimicrobial and anticancer properties by incorporation of ethanolic extract of Garcinia mangostana peel.

Natural polymeric nanofibers-based materials for medical application is an intensive research area due to the unique features of natural polymeric nanofibers. Bacterial nanocellulose (BC) films containing various concentrations of mangosteen (Garcinia mangostana) peel extract were prepared and evaluated as a multifunctional nanofiber film. The extract was absorbed into BC hydrogel and air dried to entrap the extract into nanofiber network. The resulting films contained about 3, 35, and 294 mg of total phenolic compounds and 2, 24, and 250 mg of α-mangostin per cm3 of the dried films. The film containing the highest phenolic compounds and α-mangostin performed the inhibitory effect to Staphylococcus epidermidis, Propionibacterium acnes, and Staphylococcus aureus. High anticancer activity against B16F10 melanoma and MCF-7 breast cancer cells having viabilities of 10 and 5%, respectively after 48 h were detected after the treatments with the film. However, the film had a low toxicity against normal fibroblast and keratinocyte cells with 41 and 99% viability, respectively. The research suggested that the prepared films were a multifunctional nanofiber films with antimicrobial and anticancer properties.

Curcumin-Loaded Bacterial Cellulose/Alginate/Gelatin as A Multifunctional Biopolymer Composite Film.

Multifunctional biopolymer composites comprising mechanically-disintegrated bacterial cellulose, alginate, gelatin and curcumin plasticized with glycerol were successfully fabricated through a simple, facile, cost-effective mechanical blending and casting method. SEM images indicate a well-distributed structure of the composites. The water contact angles existed in the range of 50-70°. Measured water vapor permeability values were 300-800 g/m2/24 h, which were comparable with those of commercial dressing products. No release of curcumin from the films was observed during the immersion in PBS and artificial saliva, and the fluid uptakes were in the range of 100-700%. Films were stretchable and provided appropriate stiffness and enduring deformation. Hydrated films adhered firmly onto the skin. In vitro mucoadhesion time was found in the range of 0.5-6 h with porcine mucosa as model membrane under artificial saliva medium. The curcumin-loaded films had substantial antibacterial activity against E. coli and S. aureus. The films showed non-cytotoxicity to human keratinocytes and human gingival fibroblasts but exhibited potent anticancer activity in oral cancer cells. Therefore, these curcumin-loaded films showed their potential for use as leave-on skin applications. These versatile films can be further developed to achieve desirable characteristics for local topical patches for wound care, periodontitis and oral cancer treatment.

Cyclic tensile force-upregulated IL6 increases MMP3 expression by human periodontal ligament cells.

OBJECTIVE: Cyclic tensile force (CTF) modulates physiological responses of periodontal ligament (PDL) cells. PDL cells are mechanosensitive and are able to maintain tissue homeostasis; a process mediated by the expression of particular cytokines including interleukin 6 (IL6). It is unknown whether CTF-induced IL6 regulates the expression of MMPs, enzymes needed for tissue remodeling. DESIGN: Human PDL cells were subjected to 10% elongation strain of CTF at a frequency of 60 rpm continuously for 6 h. RNA and proteins were extracted and analyzed for IL6 and MMP expression by quantitative real-time PCR and ELISA, respectively. Using a neutralizing anti-IL6 antibody and addition of recombinant human IL6 at concentrations of 0.1, 1, 10 ng.mL-1 were performed to clarify whether CTF-upregulated IL6 increased MMP expression. Inhibitors of intracellular signaling molecules were employed to reveal possible pathway(s) of IL6-induced MMP expression. RESULTS: CTF-induced IL6 expression coincided with an increased MMP3 expression. A neutralizing anti-IL6 antibody attenuated the CTF-increased MMP3 expression, whereas stimulating the cells with recombinant human IL6 increased MMP3 expression. Both PI3K and MAPK pathways were essential in the IL6 induced expression of MMP3. CONCLUSION: Our findings suggest a role of CTF in the modulation of expression of IL6 and MMP3 and thus in the regulation of homeostasis and remodeling of the periodontal ligament.

Fabrication and characterization of novel bacterial cellulose/alginate/gelatin biocomposite film.

Hydrogels from bacterial, algal, and animal cells-bacterial cellulose (BC), alginate, and gelatin, respectively-were combined to fabricate a biocomposite film (BCAGG) via an eco-friendly casting technique. In addition, glycerol was added as a plasticizer to improve the elasticity and water absorption capacity of the film. In this study, BC pellicles were simply deconstructed into fibrils suspension and then reconstructed into films with a supplement of alginate, gelatin and glycerol. The physical appearance of fabricated films resembled native BC but possessed improved ductility, enhanced flexibility, higher water uptake ability and better biocompatibility. The film was found to resist tearing under suture pullout strength in a hydrated state. In vitro cytotoxicity tests showed that the film was cytocompatible. A cell study using a human keratinocyte culture demonstrated enhanced cell adhesion, spreading, and proliferation on the BCAGG film compared with BC/alginate film. The BCAGG film therefore has significant potential for use in biomedical applications, particularly in dermal treatment, skin tissue regeneration, and wound healing.

Grape Seed Extract Reduces Active Gelatinases Using an Etch-and-Rinse Mode Universal Adhesive.

PURPOSE: To examine the effect of grape seed extract (GSE) pretreatment on the reduction of active gelatinases when using universal adhesives in etch-and-rinse mode. MATERIALS AND METHODS: Fifty extracted non-carious human teeth were used in this study. Dentin powder was prepared for analysis of active MMP-2 by ELISA. Resin-dentin slices were prepared for in situ zymography in order to localize active gelatinases by quenched fluorescein-conjugated gelatin under a confocal microscope. Fluorescence intensity was analyzed quantitatively. Specimens were allocated into 6 groups: a non-treated control, phosphoric acid etched (PA), PA followed by Single Bond Universal (SBU, 3M Oral Care) or G-Premio Bond (GPB, GC), and PA followed by GSE for 1 min prior to SBU or GPB. The data were analyzed with one-way ANOVA and Bonferroni's test at a significance level of 0.05. RESULTS: Application of the universal adhesives SBU and GPB in etch-and-rinse mode reduced active MMP-2 in dentin matrices. However, the only further significant reduction was found in GPB pre-treated with GSE, as analyzed by ELISA. In situ zymography demonstrated the location of active gelatinases, and fluorescence intensity analysis confirmed significant reduction of active gelatinases in the hybrid layer of GPB pre-teated with GSE compared to GPB alone. CONCLUSION: The present study demonstrated the potential advantage of applying GSE to reduce active gelatinases especially at the hybrid layer, with greater benefit achieved for hydrophobic adhesives. Nevertheless, the mechanism of action, analysis of bond strength, and long-term efficacy require further study.

Cyclic tensile force stimulates BMP9 synthesis and in vitro mineralization by human periodontal ligament cells.

Periodontal ligament (PDL) cells are mechanosensitive and have the potential to differentiate into osteoblast-like cells under the influence of cyclic tensile force (CTF). CTF modulates the expression of regulatory proteins including bone morphogenetic proteins (BMPs), which are essential for the homeostasis of the periodontium. Among the BMPs, BMP9 is one of the most potent osteogenic BMPs. It is yet unknown whether CTF affects the expression of BMP9 and mineralization. Here, we demonstrated that continuously applied CTF for only the first 6 hr stimulated the synthesis of BMP9 and induced mineral deposition within 14 days by human PDL cells. Stimulation of BMP9 expression depended on ATP and P2Y 1 receptors. Apyrase, an ecto-ATPase, inhibited CTF-mediated ATP-induced BMP9 expression. The addition of ATP increased the expression of BMP9. Loss of function experiments using suramin (a broad-spectrum P2Y antagonist), MRS2179 (a specific P2Y 1 receptor antagonist), MRS 2365 (a specific P2Y 1 agonist), U-73122 (a phospholipase C [PLC] inhibitor), and thapsigargin (enhancer of intracytosolic calcium) revealed the participation of P2Y 1 in regulating the expression of BMP9. This was mediated by an increased level of intracellular Ca 2+ through the PLC pathway. A neutralizing anti-BMP9 antibody decreased mineral deposition, which was stimulated by CTF for almost 45% indicating a role of BMP9 in an in vitro mineralization. Collectively, our findings suggest an essential modulatory role of CTF in the homeostasis and regeneration of the periodontium.

Structural modification and characterization of bacterial cellulose-alginate composite scaffolds for tissue engineering.

A novel bacterial cellulose-alginate composite scaffold (N-BCA) was fabricated by freeze drying and subsequent crosslinking with Ca(2+). The N-BCA then underwent a second freeze drying step to remove water without altering the physical structure. A stable structure of N-BCA with open and highly interconnected pores in the range of 90-160 µm was constructed. The N-BCA was stable in both water and PBS. The swelling ability of N-BCA in water was approximately 50 times its weight, which was about 6.5 times that of the freeze dried bacterial cellulose pellicles. N-BCA demonstrated no cytotoxicity against L929 mouse fibroblast cells. For long-term culture, N-BCA supported attachment, spreading, and proliferation of human gingival fibroblast (GF) on the surface. However, under static conditions, the cell migration and growth inside the scaffold were limited. Because of its biocompatibility and open macroporous structure, N-BCA could potentially be used as a scaffold for tissue engineering.

TNF-α stimulates MMP-3 production via PGE2 signalling through the NF-kB and p38 MAPK pathway in a murine cementoblast cell line.

BACKGROUND: Cementoblasts are considered to play an important role in the homeostasis of periodontal tissues under both physiologic and pathologic conditions. Matrix metalloproteinases (MMPs) is the key family of enzymes participating in extracellular matrix remodelling. In the present study, the effects and regulatory mechanisms of tumour necrosis factor (TNF)-α on the expression of MMPs and their inhibitors (tissue inhibitor of metalloproteinases; TIMPs) were investigated. MATERIALS AND METHODS: OCCM-30, an immortalised murine cementoblast cell line, was stimulated with TNF-α at 1 and 10ng/ml for 24h. The expression of Mmp-2, Mmp-3, Mmp-13, Mmp-14, Timp-1, and Timp-2 as well as PGE2 was determined. Inhibitors of MAPKs, PI3K/Akt, NF-kB and Cox-2 were employed to reveal possible TNF-α induced regulatory signalling pathway(s). The mRNA and protein expression were analysed by (semi)quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: TNF-α dose-dependently stimulated MMP-3 expression by cementoblasts. This was found for mRNA as well as protein expression. No significant differences were found in the mRNA expression of Mmp-2, Mmp-13, Mmp-14, Timp-1, and Timp-2 upon TNF-α stimulation. The level of PGE2, however, was significantly increased along with MMP-3. Treatment with a selective Cox-2 inhibitor resulted in partial suppression of TNF-α-induced Mmp-3 mRNA expression. Addition of PGE2 enhanced Mmp-3 mRNA in a dose dependent manner, suggesting an inductive effect of TNF-α partly via PGE2. The up-regulation of Mmp-3 by TNF-α was completely suppressed by a combination of NF-kB and p38 MAPK inhibitors, while partial suppression was found with each inhibitor. The effect of PGE2 on Mmp-3 expression was abolished by treating cells with an NF-kB inhibitor; a p38 MAPK inhibitor had only a small effect. CONCLUSIONS: The present study indicates that cementoblasts respond to TNF-α by increasing MMP-3 production partially via PGE2 and signalling through the NF-kB and p38 MAPK pathway. MMP-3 may participate in periodontal tissue degradation/remodelling.

Biocompatibility and growth of human keratinocytes and fibroblasts on biosynthesized cellulose-chitosan film.

Bacterial cellulose (BC)-chitosan (BCC) films made via bio-co-polymerization by Acetobacter xylinum were developed and characterized for physical and biological properties. With the incorporation of chitosan MW 3 x 10(4) and 8 x 10(4) into bacterial cellulose, the modified films (BCC-MW 30,000 and BCC-MW 80,000, respectively) became denser, with a smaller average pore size of 13.1-15.3 nm in dry form. The BCC films have no toxicity against L929 mouse fibroblast cells. Tissue compatibility was then evaluated by growth and spreading of human skin keratinocytes and fibroblasts. The results revealed that the growth of human skin keratinocytes and fibroblasts on the BCC films was comparable to that on the BC film; however, improvement of cell adhesion and spreading on the BCC films was observed in human skin keratinocytes. The results of the biological response experiments showed no significant difference between BCC-MW 30,000 and BCC-MW 80,000.

Loading of curcumin in polyelectrolyte multilayers.

Polyelectrolyte multilayer (PEM) thin films prepared using the layer-by-layer technique are proposed as a matrix for the immobilization of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-2,5-dione (curcumin), a lipophilic model drug. The PEM assembly was based on the layer-by-layer deposition of cationic poly(diallyldimethyl-ammonium chloride) (PDADMAC) and anionic poly(4-styrene sulfonate, sodium salt) (PSS) onto a quartz slide. Curcumin was loaded by dipping the PEM film into a dilute solution of curcumin dispersed in an 80/20% v/v water/ethanol solution. Within a few minutes, the film turned bright yellow as a result of the curcumin loading. The effect of the solvent composition, curcumin concentration and film thickness on the final concentration of curcumin in the PEM films was measured by UV-vis spectroscopy. The loading of curcumin was driven by its partitioning in the PEM film, and its partitioning coefficient between the 80/20 solvent and the PEM thin film was found to have a value of 2.07 x 10(5). The extinction coefficient of curcumin loaded into PEM was calculated to 64,000 M(-1) cm(-1). Results show that the loading of curcumin into the PEM films increased with the number of deposited layers, implying that curcumin partitioned into the bulk of the thin film. The maximum curcumin dose in the PEM film was measured by exposing films of various thicknesses to a high concentration (0.01% w/v) of curcumin and recording the maximum absorbance after saturation. The films thicknesses were controlled by the number of deposited PDADMAC/PSS layers (10, 20, 30, 40, 50, and 60). Results show that increasing amounts of curcumin could be loaded into the film with an increasing number of layers and up to 8 microg/cm(2) of curcumin could be loaded into a 20-layer film. These results demonstrate that the loading of lipophilic curcumin in PEM thin films is done through a partitioning mechanism and that the PDADMAC/PSS film can be used as a loading matrix for lipophilic drugs.

Fibronectin supports TNF-alpha-induced osteopontin expression through beta1 integrin and ERK in HN-22 cells.

The extracellular matrix (ECM), in collaboration with intracellular signal, plays a critical role in the modulation of cellular behavior and function. Herein, we investigated the influence of fibronectin (FN) and tumor necrosis factor-alpha (TNF-alpha) on OPN expression in HN-22, a human head and neck squamous cell carcinoma (HNSCC) cell line. The data showed that TNF-alpha significantly increased OPN expression only in the FN-coated condition. Application of function-blocking antibody directed against beta1 integrin abolished this OPN induction. Moreover, TNF-alpha when added together with activating beta1 integrin antibody is sufficient to induced OPN expression. The combination effect of FN and TNF-alpha was significantly deteriorated by a MEK inhibitor, but not NF-kappaB inhibitor. We further demonstrated that the phosphorylation of ERK1/2 was strongly enhanced by TNF-alpha and FN compared to the application of either one alone. Synergistic effect on ERK1/2 phosphorylation was also detected by TNF-alpha and activating beta1 integrin antibody, whereas inhibitory antibody to beta1 integrin attenuated FN and TNF-alpha-induced phosphorylation of ERK1/2. Our results indicate that FN coordinates TNF-alpha-mediated OPN induction via beta1 integrin-dependent signaling mechanism that activates ERK. The results suggest the critical role of tumor micro-environment signaling networks on the regulation of cytokine expression profiles during tumor progression.

TGF-beta1 induced MMP-9 expression in HNSCC cell lines via Smad/MLCK pathway.

Matrix metalloproteinase-9 (MMP-9) plays roles in cancer progression by degrading the extracellular matrix and basement membrane. Many growth factors including Transforming growth factor-beta1 (TGF-beta1) could induce MMP-9 expression. We demonstrated that TGF-beta1 induced MMP-9 mRNA and protein in human head and neck squamous cell carcinoma cell lines. Application of TGF-beta receptor type I inhibitor (SB505124) reduced the MMP-9 expression markedly. Whilst, inhibitor of Myosin light chain kinase (MLCK) could reduce the level of secreted MMP-9 in both the supernatants and cell lysate but not the level of MMP-9 mRNA. These suggested that MLCK might regulate MMP-9 expression post-transcriptionally. Application of SB505124 and siRNA Smad2/3 reduced the phosphorylation of myosin light chain (MLC) suggested that MLC is downstream to TbetaRI/Smad2/3 signaling pathway. In conclusion, these results describe a novel mechanism for the potentiation of TGF-beta1 signaling to induce MMP-9 expression via Smad and MLCK.

Iron increases MMP-9 expression through activation of AP-1 via ERK/Akt pathway in human head and neck squamous carcinoma cells.

Head and neck squamous cell carcinoma (HNSCC) is a highly invasive cancer that is capable of distant metastasis and is a cause of great morbidity and mortality worldwide. Over-expression of matrix metalloproteinase-9 (MMP-9) is implicated in the invasion and metastasis of HNSCC. There is increasing evidence of an association between iron overload and cancer progression. However, the effect of iron on MMP-9 expression in HNSCC has not been studied. In the present study, we examined the effect of iron on MMP-9 expression in head and neck squamous carcinoma cell lines (OM-2 and HN-22). Ferric ammonium citrate (FAC), a source of iron, at 15 microg/ml increased MMP-9 in both cell lines in a dose-dependent manner as shown by reverse transcription polymerase chain reaction and gelatin zymography analyses. Studies using specific inhibitors of extracellular signal-regulated kinase (ERK1/2) and of Akt (SH-5) demonstrated that iron regulated MMP-9 through ERK1/2 and Akt, and that ERK1/2 was an upstream activator of Akt. Analysis of electrophoretic mobility shift assay revealed that iron induces MMP-9 expression by activation of activated protein-1 (AP-1). Application of neutralizing antibody against transferrin receptor could not abolish the stimulated MMP-9 expression, suggesting that iron uptake is non-transferrin dependent. In conclusion, this study is the first to demonstrate that MMP-9 was up-regulated by iron in HNSCC cell lines. We suggest that iron may be one of several factors that cause an increase of MMP-9, which is necessary for the development and progression of HNSCC.

The influence of molecular weight of chitosan on the physical and biological properties of collagen/chitosan scaffolds.

Biopolymer blends between collagen and chitosan have the potential to produce cell scaffolds with biocompatible properties. However, the relationship between the molecular weight of chitosan and its effect on physical and biological properties of collagen/chitosan scaffolds has not been elucidated yet. Porous scaffolds were fabricated by freeze-drying the solution of collagen and chitosan, followed by cross-linking by dehydrothermal treatment. Various types of scaffolds were prepared using chitosan with various molecular weights and blending ratios. Fourier transform infrared spectroscopy proved that collagen and chitosan scaffolds at all blending ratios contained mainly electrostatic interactions at the molecular level. The compressive modulus decreased with increasing the concentration of chitosan. Equilibrium swelling ratios of approximately 6-8, determined in phosphate-buffered saline at physiological pH (7.4), were found in case of collagen-dominated scaffolds. The lysozyme biodegradation test demonstrated that the presence of chitosan, especially the high-molecular-weight species, could significantly prolong the biodegradation of collagen/chitosan scaffolds. In vitro culture of L929 mouse connective tissue fibroblast evidenced that low-molecular-weight chitosan was more effective to promote and accelerate cell proliferation, particularly for scaffolds containing 30 wt% chitosan. The results elucidated that the blends of collagen with low-molecular-weight chitosan have a high potential to be applied as new materials for skin-tissue engineering.

In vitro biocompatibility of electrospun poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) fiber mats.

In the present contribution, the potential for use of the ultrafine electrospun fiber mats of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as scaffolding materials for skin and nerve regeneration was evaluated in vitro using mouse fibroblasts (L929) and Schwann cells (RT4-D6P2T) as reference cell lines. Comparison was made with PHB and PHBV films that were prepared by solution-casting technique. Indirect cytotoxicity assessment of the as-spun PHB and PHBV fiber mats with mouse fibroblasts (L929) and Schwann cells (RT4-D6P2T) indicated that the materials were acceptable to both types of cells. The attachment of L929 on all of the fibrous scaffolds was significantly better than that on both the film scaffolds and tissue-culture polystyrene plate (TCPS), while RT4-D6P2T appeared to attach on the flat surfaces of TCPS and the film scaffolds much better than on the rough surfaces of the fibrous scaffolds. For L929, all of the fibrous scaffolds were superior in supporting the cell proliferation to the film counterparts, but inferior to TCPS at days 3 and 5, while, for RT4-D6P2T, the rough surfaces of the fibrous scaffolds appeared to be very poor in supporting the cell proliferation when comparing with the smooth surfaces of TCPS and the film scaffolds. Scanning electron microscopy was also used to observe the behavior of both types of cells that were cultured on both the fibrous and the film scaffolds and glass substrate for 24 h.

Growth of human keratinocytes and fibroblasts on bacterial cellulose film.

Thin films of bacterial cellulose (BC) from a nata de coco culture system were developed, characterized, and investigated for the growth of human keratinocytes and fibroblasts. The average pore diameter and total surface area of the dried BC films estimated by BET were 224 A and 12.62 m(2)/g, respectively. With an film thickness of 0.12 mm, the average tensile strength and break strain of the dried films were 5.21 MPa and 3.75%, whereas those of the wet films were 1.56 MPa and 8.00%, respectively. The water absorption capacity of air-dried film was 5.09 g water/g dried films. For uses in the therapy of skin wounds, the potential biological mechanism of action of BC film was evaluated by using human keratinocytes and fibroblasts. Our results were the first direct demonstration that BC film supported the growth, spreading, and migration of human keratinocytes but not those of human fibroblasts. Expressions of E-cadherin and the alpha-3 chain of laminin confirmed the phenotype of human keratinocytes on BC film.

Novel bone scaffolds of electrospun polycaprolactone fibers filled with nanoparticles.

Novel bone scaffolding materials were successfully fabricated by electrospinning from polycaprolactone (PCL) solutions containing nanoparticles of calcium carbonate (CaCO3) or hydroxyapatite (HA). The potential use of the electrospun fibrous scaffolds for bone regeneration was evaluated in vitro with human osteoblasts (SaOS2) in terms of attachment, proliferation, and alkaline phosphatase (ALP) activity of the cells that were cultured directly on the scaffolds. The results were compared with those on corresponding solution-cast film scaffolds and tissue-culture polystyrene plate (TCPS). It was found that all of the fibrous scaffolds promoted much better adhesion and proliferation of cells than the corresponding film scaffolds and TCPS. Interestingly, the cells that were seeded on all of the fibrous scaffolds appeared to be well-expanded and attach on the fiber surface very well even only about 1 hr in culture, while those seeded on all of the film scaffolds and the glass substrate were still in round shape. Among the various fibrous scaffolds investigated, the one that was filled with 1.0% HA showed the highest ALP activity. Finally, all of the fibrous scaffolds exhibited much greater tensile strength at yield than all of the corresponding film scaffolds.

Preparation and characterization of novel bone scaffolds based on electrospun polycaprolactone fibers filled with nanoparticles.

Novel bone-scaffolding materials were successfully fabricated by electrospinning from polycaprolactone (PCL) solutions containing nanoparticles of calcium carbonate (CaCO(3)) or hydroxyapatite (HA). The diameters of the as-spun fibers were found to increase with the addition and increasing amounts of the nanoparticles. The observed increase in the diameters of the as-spun fibers with the addition and increasing amounts of the nanoparticulate fillers was responsible for the observed increase in the tensile strength of the obtained fiber mats. An increase in the concentration of the base PCL solution caused the average diameter of the as-spun PCL/HA composite fibers to increase. Increasing applied electrical potential also resulted in an increase in the diameters of the obtained PCL/HA composite fibers. Lastly, indirect cytotoxicity evaluation of the electrospun mats of PCL, PCL/CaCO(3), and PCL/HA fibers based on human osteoblasts (SaOS2) and mouse fibroblasts (L929) revealed that these as-spun mats posed no threat to the cells, a result that implied their potential for utilization as bone-scaffolding materials.

Preparation and characterization of microwave-treated carboxymethyl chitin and carboxymethyl chitosan films for potential use in wound care application.

CM-chitin and CM-chitosan films were successfully crosslinked by microwave treatment. Crosslinking of the microwave-treated CM-chitin films involved mainly the carboxylate and the secondary alcohol groups, while crosslinking of microwave-treated CM-chitosan films involved the carboxylate and the amino groups. In addition, the crystallinity of CM-chitin increased with increasing microwave treatment time, whereas an increase in the crystallinity of the microwave-treated CM-chitosan films was not observed. At a similar percentage of weight loss, the crosslinking of either CM-chitin or CM-chitosan films by microwave treatment required much less stringent condition when compared with the crosslinking by autoclave treatment. Based on both direct and indirect cytotoxicity assays, the cytotoxicity of the microwave-treated CM-chitin films was negative, while that of the microwave-treated CM-chitosan films was positive. Human fibroblasts adhered on the surface of microwave-treated CM-chitosan films much better than on the surface of microwave-treated CM-chitin films.