RESUMO
Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging nosocomial pathogen among hospitalized patients, with high morbidity and mortality rates. The discovery of a novel antibacterial is urgently needed to address this resistance problem. The present study aims to explore the antibacterial potential of three depsidone compounds: 2-clorounguinol (1), unguinol (2), and nidulin (3), isolated from the marine sponge-derived fungus Aspergillus unguis IB1, both in vitro and in silico. The antibacterial activity of all compounds was evaluated by calculating the Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) against MRSA using agar diffusion and total plate count methods, respectively. Bacterial cell morphology changes were studied for the first time using scanning electron microscopy (SEM). Molecular docking, pharmacokinetics analysis, and molecular dynamics simulation were performed to determine possible protein-ligand interactions and the stability of the targeting penicillin-binding protein 2a (PBP2a) against 2-clorounguinol (1). The research findings indicated that compounds 1 to 3 exhibited MIC and MBC values of 2 µg/mL and 16 µg/mL against MRSA, respectively. MRSA cells displayed a distinct shape after the addition of the depsidone compound, as observed in SEM. According to the in silico study, 2-chlorounguinol exhibited the highest binding-free energy (BFE) with PBP2a (-6.7 kcal/mol). For comparison, (E)-3-(2-(4-cyanostyryl)-4-oxoquinazolin-3(4H)-yl) benzoic acid inhibits PBP2a with a BFE less than -6.6 kcal/mol. Based on the Lipinski's rule of 5, depsidone compounds constitute a class of compounds with good pharmacokinetic properties, being easily absorbed and permeable. These findings suggest that 2-chlorounguinol possesses potential antibacterial activity and could be developed as an antibiotic adjuvant to reduce antimicrobial resistance.
RESUMO
BACKGROUND: This study aimed to analyze the effect of a high-fat and high-fructose diet (HFFD) on the digesta weight and shortchain fatty acid (SCFA) levels of cecal digesta in rats. METHODS: This study was an experimental study with a posttest-only control group design with male Sprague-Dawley strain rats as the samples. A total of 36 rats were divided into two groups with normal diet (N) and modified HFFD. The data of energy intake, nutrients and fiber, body weight, Lee index, abdominal circumference, digesta weight, and SCFA levels of cecal digesta were collected. RESULTS: The results showed an 11.94% increase in body weights of rats with HFFD. The total energy intake of the HFFD group was significantly higher than that of N (p = 0.000). The fiber intake and cecal digesta weight in group N were higher than that in the HFFD group (p = 0.00 and p = 0.02, respectively). The concentrations of acetate, butyrate, propionate, and total SCFA in the N group were significantly higher than in the HFFD (p = 0.041,,p = 0.004, p = 0.040, p = 0.013, respectively). A significant negative relationship was observed between the abdominal circumference and cecal digesta concentration (p = 0.029; r = -0.529) and between the Lee index and the SCFA concentration of cecal digesta (p = 0.036, r = -0.206).
Assuntos
Frutose , Propionatos , Acetatos , Animais , Butiratos , Dieta , Dieta Hiperlipídica , Ácidos Graxos , Ácidos Graxos Voláteis , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Sponge-derived fungi have recently attracted attention as an important source of interesting bioactive compounds. Aspergillus nomius NC06 was isolated from the marine sponge Neopetrosia chaliniformis. This fungus was cultured on rice medium and yielded four compounds including three new oxisterigmatocystins, namely, J, K, and L (1, 2, and 3), and one known compound, aspergillicin A (4). Structures of the compounds were elucidated by 1D and 2D NMR spectroscopy and by high-resolution mass spectrometry. The isolated compounds were tested for cytotoxic activity against HT 29 colon cancer cells, where compounds 1, 2, and 4 exhibited IC50 values of 6.28, 15.14, and 1.63 µM, respectively. Under the fluorescence microscope by using a double staining method, HT 29 cells were observed to be viable, apoptotic, and necrotic after treatment with the cytotoxic compounds 1, 2, and 4. The result shows that compounds 1 and 2 were able to induce apoptosis and cell death in HT 29 cells.
Assuntos
Antineoplásicos/farmacologia , Aspergillus , Poríferos , Animais , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Organismos Aquáticos , Linhagem Celular Tumoral/efeitos dos fármacos , HumanosRESUMO
The evidence on the role of diets in the production of short-chain fatty acids (SCFAs) was limited. The aim of this study was to assess the potential effects of high-fat high-fructose (HFHF), high-fat, and Western diets on the levels of SCFA. A research experiment employing a post-test-only control group design was carried out from January to April 2022. A total of 27 rats were randomly allocated to each study group. SCFA was measured two weeks after diet administration. Analysis of variance (ANOVA) test was used to analyze the differences among groups, and the effect estimate of each group was analyzed using post hoc Tukey. The concentrations of SCFAs post HFHF diets were recorded as follows: acetic acid at 54.60±10.58 mmol/g, propionic acid at 28.03±8.81 mmol/g, and butyric acid at 4.23±1.68 mmol/g. Following the high-fat diet, acetic acid measured 61.85±14.25 mmol/gr, propionic acid measured 25.19±5.55 mmol/gr, and butyric acid measured 6.10±2.93 mmol/gr. After the administration of Western diet, the levels of SCFA were 68.18±25.73, 29.69±12.76, and 7.48±5.51 mmol/g for acetic acid, propionic acid, and butyric acid, respectively. The level of butyric acid was significantly lower in HFHF diet group compared to the normal diet (mean difference (MD) 6.34; 95%CI: 0.61, 12.04; p=0.026). The levels of acetic acid (p=0.419) and propionic acid (p=0.316) were not statistically different among diet types (HFHF, high-fat, and Western diet). In conclusion, HFHF diet is associated with a lower level of butyric acid than the normal diet in a rat model.
Assuntos
Dieta Hiperlipídica , Dieta Ocidental , Modelos Animais de Doenças , Ácidos Graxos Voláteis , Frutose , Hepatopatia Gordurosa não Alcoólica , Animais , Ratos , Dieta Hiperlipídica/efeitos adversos , Ácidos Graxos Voláteis/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/patologia , Frutose/administração & dosagem , Dieta Ocidental/efeitos adversos , Masculino , Ratos Sprague-Dawley , Ácido AcéticoRESUMO
The research aims to identify the chemical constituents of endophytic fungi associated with Gynura japonica and their biological activities. Two endophytic fungi, labelled as GS-1 and GS-2, have been isolated from the leaves of G. japonica. They were cultivated on white rice media for their optimum cultivation time. Cultivated fungi were extracted with ethyl acetate and concentrated to give a crude extract. All crude extracts were evaluated for their phytochemical screening and assayed for their antibacterial and antioxidant activities. Based on the results, fungal GS-1 was the most potential fungus to produce bioactive secondary metabolites and identified as Dimorphiseta acuta. A bioactive compound was isolated from crude extract of fungal D. acuta and identified as emodin. To the best of our knowledge, the study of secondary metabolite and its biological activity of endophytic fungus colonised with the leaves of G. japonica is reported here for the first time.
RESUMO
The physical and mechanical properties of biopolymers can be improved by heating technologies. In this research, we improved the properties of Polyvinyl alcohol (PVA)/Uncaria gambir extract (UGE) blend films by post-heating method. After post-heating, the blend film exhibited higher resistance to UV light and improved contact angle performance, while water vapor permeability and moisture absorption decreased. The tensile strength and toughness of the PVA/UGE blend film with a post-heating duration of 40 min were 68.8 MPa and 57.7 MPa, respectively, an increase of 131 % and 127 %, compared to films without post-heating. This facile and cost-effective fabrication method, with environmentally friendly properties, can be applied to biodegradable PVA/UGE blend films to achieve desired properties for optical devices or food packaging materials.
RESUMO
Background: Consumed fructose enters enterocytes of the intestinal epithelial apical membrane mediated by glucose transporter 5 (GLUT5). Aim: To determine the effects of Lombok Island's local Moringa leaf powder on reducing liver fructose levels and GLUT5 expression in the small intestine of albino rats (Rattus novergicus) fed a high-fructose diet. Methods: Moringa leaf (Moringa oleifera) was obtained from Lombok Island, Indonesia. Subsequently, 30 male albino rats (R. novergicus) were used, divided into the normal group (NG), treatment group 1 (T1G), treatment group 2 (T2G), Quercetin group (QG), Moringa group (MG). Quercetin and moringa leaf powder (M. oleifera) was administered at 50 and 500 mg/kgbw for 28 days. Enzyme-linked immunosorbent assay (Elisa) method was used to examine liver fructose levels. The observation of GLUT5 expression in the small intestine was performed by the Immunofluorescence method. Results: The ANOVA test proved that there are significant differences (p < 0.005) in liver fructose levels in all groups. Further post hoc tests show no significant difference (p > 0.005) in liver fructose levels in rats fed a high fructose diet in T1G and T2G with QG and MG rats. However, Moringa leaf powder reduces liver fructose levels by 32.1% and 17.2% in T1G and T2G rats, respectively. The ANOVA test showed a significant difference (p < 0.005) in the expression of GLUT5 in all groups. Further post hoc tests showed a significant difference (p < 0.005) in the expression of GLUT5 in the duodenum, jejunum, and ileum between the NG and the T1G rats. Meanwhile, in T2G rats, significant differences were only found in the jejunum. Moringa leaf powder reduces GLUT5 expression in T1G rats by 44.5%, 59.5%, and 57.2% in the duodenum, jejunum, and ileum, whereas in T2G rats is by 33.5%, 50.2%, and 48.1%, respectively. Conclusion: The administration of local moringa (M. oleifera) leaf powder in Lombok Island had an effect on reducing GLUT5 expression in the small intestine, however, did not in liver fructose levels of albino rats (R. novergicus) fed a high-fructose diet.
Assuntos
Moringa oleifera , Moringa , Masculino , Animais , Ratos , Pós , Quercetina , Fígado , Dieta/veterinária , Frutose/farmacologia , Folhas de PlantaRESUMO
Background: The spectrum of non-alcoholic fatty liver disease (NAFLD), known as non-alcoholic steatohepatitis (NASH), can lead to advanced liver disease. It is known that a variety of diets play a significant role in the development of NAFLD/NASH. The goal of this study was to determine the most appropriate composition of diet to induce NASH in an animal model. Methods: This research used Rattus norvegicus strain Wistar (n=27), which were divided into four groups and given each diet for 12 weeks: normal diet (ND, n=7), high-fat diet (HFD, n=6), western diet (WD, n=7), and high-fat-high-fructose diet (HFHFD, n=7). Subjects were monitored for changes in body weight. Blood samples were collected for biochemical analysis, including low-density lipoprotein (LDL), triglyceride, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), hepatic lipase, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and lipopolysaccharide (LPS). Fecal samples were taken for short-chain fatty acid (SCFA) analysis. Liver histology was assessed using NAS (NAFLD activity score). A statistical comparison test was carried out using the one-way ANOVA or Kruskal-Wallis test. Results: The highest average body weight was observed in the WD group (346.14 g). Liver enzymes, LDL, triglyceride, propionic acid, and acetic acid did not show significantly differences among the groups. TNF-α, IL-6, and hepatic lipase were significant (p = 0.000; p = 0.000; p = 0.004) and the highest level recorded in the HFD group. Butyrate acid level also showed significances (p = 0.021) with the lowest concentration seen in the HFHFD group (4.77 mMol/g). Only WD and HFHFD had a NAS ≥ 5 (14% and 14%). The highest percentage of borderline NAS was found in WD (57%). Conclusions: WD feeding is the most appropriate diet type to induce NASH in rats as it influences metabolic, inflammatory, dysbiosis, and liver histology of rats.
Assuntos
Biomarcadores , Dieta Hiperlipídica , Modelos Animais de Doenças , Disbiose , Fígado , Hepatopatia Gordurosa não Alcoólica , Ratos Wistar , Animais , Hepatopatia Gordurosa não Alcoólica/patologia , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/metabolismo , Dieta Hiperlipídica/efeitos adversos , Fígado/patologia , Fígado/metabolismo , Ratos , Masculino , Biomarcadores/sangue , Inflamação/patologiaRESUMO
OBJECTIVES: Adipogenesis is the fat cell formation process regulated by peroxisome proliferator-activated receptors (PPARγ). The insulin-responsive glucose transporter 4 (GLUT4) has a major role in glucose uptake and metabolism in insulin target tissues (i.e., adipose and muscle cells). The interplay between PPARγ and GLUT4 is essential for proper glucose homeostasis. This study aimed to isolate, elucidate, and investigate the effect of an isolated compound from Penicillium citrinum XT6 on adipogenesis, PPARγ, and GLUT4 expression in 3T3-L1 adipocytes. METHODS: The isolated compound was determined by analyzing spectroscopic data (LC-MS, FT-IR, Spectrophotometry UV-Vis, and NMR). The adipogenesis activity of the isolated compound in 3T3-L1 cells was determined by the Oil Red O staining method. RT-PCR was used to analyze the gene expression of PPARγ and GLUT4. RESULTS: Di-(2-ethylhexyl)-phthalate (DEHP) was the isolated compound from P.citrinum XT6. The results revealed adipogenesis stimulation and inhibition, as well as PPARγ and GLUT4 expressions. CONCLUSIONS: DEHP showed a non-monotonic dose-response (NMDR) effect on adipogenesis and PPARγ and GLUT4 expression. It is the first study that reveals DEHP's NMDR effects on lipid and glucose metabolism in adipocytes.
Assuntos
Adipogenia , Dietilexilftalato , Camundongos , Animais , PPAR gama/genética , PPAR gama/metabolismo , PPAR gama/farmacologia , Células 3T3-L1 , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Glucose/metabolismo , Glucose/farmacologia , Adipócitos/metabolismoRESUMO
Purpose: During Plasmodium berghei (P. berghei) infection, infected erythrocytes are sequestered in gut tissues through microvascular circulation, leading to dysbiosis. This study aimed to investigate the effect of Lactobacillus casei (L. casei) and Bifidobacterium longum (B. longum) administration on the parasitemia level, gut microbiota composition, expression of cluster of differentiation 103 (CD103) in intestinal dendritic and T regulatory cells (T reg), plasma interferon gamma (IFN-γ) and tumor necrosis factor (TNF-α) levels in P. berghei infected mice. Methods: P. berghei was inoculated intraperitoneally. Infected mice were randomly divided into 5 groups and treated with either L. casei, B. longum, or the combination of both for 5 days before up to 6 days post-infection (p.i). The control group was treated with phosphate-buffered saline (PBS), while uninfected mice were used as negative control. Levels of CD103 and forkhead box P3 (FoxP3) expression were measured by direct immunofluorescense, while plasma IFN-γ and TNF-α level were determined using enzyme-linked immunosorbent assay (ELISA). Results: All treated groups showed an increase in parasitemia from day 2 to day 6 p.i, which was significant at day 2 p.i (p = 0.001), with the group receiving B. longum displaying the lowest degree of parasitemia. Significant reduction in plasma IFN-γ and TNF-α levels was observed in the group receiving B. longum (p = 0.022 and p = 0.026, respectively). The CD103 and FoxP3 expression was highest in the group receiving B. longum (p = 0.01 and p = 0.02, respectively). Conclusion: B. longum showed the best protective effect against Plasmodium infection by reducing the degree of parasitemia and modulating the gut immunity. This provides a basis for further research involving probiotic supplementation in immunity modulation of infectious diseases.
RESUMO
This work characterized bacterial cellulose (BC)/Uncaria gambir (G) biocomposite film prepared with ultrasonication treatment. Films were prepared from BC powder suspensions in distilled water without and with various loadings (0.05 g, 0.1 g, 0.2 g, 2 g) of G powder then treated using an ultrasonic probe at 1000 W for one hour. The results revealed that the ultrasonication treatment of the suspension greatly increased tensile strength (TS), elongation at break (EB), and toughness (TN) of a BC film by 3097%, 644%, and 32,600%, respectively, compared to non-sonicated BC film. After adding 0.05 g G into the sonicated BC powder suspension, TS, EB, and TN of the biocomposite film were improved to 105.6 MPa, 14.3%, and 8.7 MJ/m3, respectively. The addition of the G increased in antimicrobial activity of the film. This study indicates that biocomposite film is potentially useful for nanopaper production with good antimicrobial and high tensile properties.
Assuntos
Uncaria , Antibacterianos/farmacologia , Celulose , Polímeros , Pós , Resistência à TraçãoRESUMO
OBJECTIVES: Gestational diabetes (GDM) complications affect maternal and fetus in utero. GDM's vascular dysfunction showed inducible nitric oxide synthase (iNOS) alteration and was linked to the higher production of nitrogen species, leading to diabetic embryopathy. Ocimum basilicum (O. basilicum) has been reported for its anti-inflammatory and anti-diabetic effects. Thus, the present study investigates the anti-diabetic effect, lipid-lowering effect, and iNOS expression in GDM animal models treated with O. basilicum extract. EXPERIMENTAL PROCEDURES: Four groups of pregnant rats consist of control and GDM groups. One GDM group was set for control positive. Two GDM groups were treated with O. basilicum extract in two doses (100 and 200 mg/kg BW) for 14 days. Blood glucose of all groups was observed at 72 h after STZ injection and 14 days after administration of O. basilicum extract. Lipid profile and iNOS expression using real-time PCR were measured afterward. RESULTS: O. basilicum extract lowered blood glucose levels in both doses, from 262.60 mg/dL±6.89-136.80 mg/dL ± 15.6 mg/dL and 113.20 mg/dL±5.25 mg/dL. Total cholesterol, LDL and triglyceride showed a reduction, especially in 200 mg/kg BW dose extract from 122.37 mg/dL ± 14.84 mg/dL, 69.75 mg/dL±3.78 mg/dL and 137.51 mg/dL ± 8.12-74.64 mg/dL±8.71 mg/dL, 40.26 mg/dL±3.31 mg/dL and 87.57 mg/dL±6.29 mg/dL, respectively. iNOS expression downregulated in both doses, from 2.17±0.39 to 0.94±0.3 and 0.41±0.08. CONCLUSIONS: This study showed that O. basilicum extract has a potential therapeutic activity in lowering blood glucose, improved lipid profile, and downregulating iNOS in GDM.
Assuntos
Diabetes Gestacional , Ocimum basilicum , Animais , Anti-Inflamatórios , Glicemia , LDL-Colesterol , Diabetes Gestacional/tratamento farmacológico , Feminino , Humanos , Óxido Nítrico Sintase Tipo II/genética , Nitrogênio , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Gravidez , Ratos , TriglicerídeosRESUMO
BACKGROUND: Diabetes mellitus is a metabolic disorder whose prevalence increases globally. Medical nutrition therapy (MNT) is one of the DM management pillars to control blood glucose. Local Indonesian brown rice is proven to contain high fiber and magnesium levels thus could improve obesity, fasting blood glucose, and HbA1c This study aims to prove the benefits of brown rice on anthropometric parameters and blood glucose control. DESIGN AND METHODS: Respondents were overweight women older than 40 years with type 2 diabetes who were given three main meals and three snacks six days a week for 12 weeks. Anthropometric and blood glucose control data were collected before and after the intervention. Diet and intake data before the intervention were obtained through a semi quantitate food frequency questionnaire. Intake data during the intervention were recorded using the 24-hour food record and analyzed using modified NutriSurvey 2007 software. RESULTS: Brown rice intervention significantly reduced body weight, BMI, body fat percentage, and abdominal circumference (p<0.05), also in fasting blood glucose (FBG), 2-h postprandial blood glucose (PBG), and HbA1c (p<0.05). From the Pearson's test results, an increase in fiber intake correlated with a decrease in BMI and abdominal circumference (p=0.03; r = -0.511 and p=0.006; r = -0.619, respectively). Meanwhile, magnesium intake and changes in BMI showed a negative correlation. CONCLUSIONS: The substitution of brown rice as a staple food for 12 weeks improves anthropometric parameters and blood glucose control in respondents with type 2 diabetes.
RESUMO
BACKGROUND: Dietary fats and fructose have been responsible for inducing obesity and body tissues damage due to the consequence of metabolic syndrome through several mechanisms. The body fat index (BFI) is one of the anthropometric measures used to detect obesity in rats. This study aims to examine the correlation between high-fat high-fructose diet and liver steatosis cell count, early atherosclerosis characteristics, and BFI in Sprague Dawley Rats. DESIGN AND METHODS: This was an experimental design using 2 groups of 12-weeks-old Sprague Dawley (SD) rats. The control group received a standard diet and tap water beverages for 17 weeks. The intervention group was fed with high-fat diet from modified AIN 93-M and additional 30% fructose drink. We analyzed the foam cell count, aortic wall thickness, cardiac histopathology, and liver steatosis cell count after the sacrifice process. RESULTS: The rats in the intervention group had a higher aortic wall thickness, liver steatosis, and foam cell count (+125%, p<0.01; +317%, p<0.01 and +165%, p<0.01 respectively) compared to the control group. The intervention group also showed higher mononuclear inflammatory and hypertrophic cell count. A significant positive correlation was found between dietary fructose with premature atherosclerosis by increasing foam cell count (r=0.66) and aortic wall thickness (r=0.68). In addition, 30% dietary fructose increased liver steatosis (r =0.69) and mononuclear inflammatory cardiac cell count (r=0.61). Interestingly, the intervention had no effect on BFI (p>0.5; r=0.13). CONCLUSIONS: Dietary fat and fructose consumption for 17 weeks promote atherosclerosis, liver steatosis, and cardiac histopathology alteration without increasing BFI.
RESUMO
Transparent film with high thermal resistance and antimicrobial properties has many applications in the food packaging industry particularly packaging for reheatable food. This work investigates the effects of heat treatment on the thermal resistance, stability of transparency and antimicrobial activity of transparent cellulose film. The film from ginger nanocellulose fibers was prepared with chemicals and ultrasonication. The dried film was heated at 150⯰C for 30, 60, 90, or 120â¯min. The unheated and sonicated film had the lowest crystallinity index and the lowest thermal properties. After heating, the film became brownish-yellow resulting from thermal oxidation. The reheated film had higher thermal resistance than unheated film. Heating led to further relaxation of cellulose network evidenced by shifting of the XRD peak positions toward lower values. The antimicrobial activity decreased due to heating. Average opacity value increases after short heating durations. It was relatively stable for further heating.
Assuntos
Anti-Infecciosos , Celulose , Nanofibras , Zingiber officinale , Bactérias/crescimento & desenvolvimento , Candida albicans/crescimento & desenvolvimento , Embalagem de Alimentos , Temperatura Alta , TubérculosRESUMO
With the increasing demand for simple, efficient, environmentally friendly preparation methods to produce cellulose nanofibers for reinforcing a biodegradable film is increased, the role of nanofibers from the pure cellulose produced by bacteria becomes more important. This work characterized bacterial cellulose nanofibers disintegrated using a high shear homogenizer. These nanofibers, in 2.5, 5, and 7.5â¯mL suspensions, were mixed with PVA gel using ultrasonication. The resulting dried bionanocomposite film was also characterized. Adding nanofiber significantly increases (pâ¯≤â¯0.05) on tensile strength, thermal resistance, water vapor impermeability, and moisture resistance of PVA film but not strain at break. Tensile strength, tensile modulus, and elongation at the break of the 7.5â¯mL nanofiber reinforced film were 37.9â¯MPa (increased by 38%), 547.8â¯MPa (increased by 26%), and 10.7% (decreased from 17.2% for pure PVA), respectively compared to pure PVA. Transparency decreases slightly with increased nanofiber content. These properties indicate that this bionanocomposite film has potential in food packaging applications.
Assuntos
Celulose/química , Nanocompostos/química , Nanofibras/química , Álcool de Polivinil/química , Sonicação , Fenômenos Ópticos , Permeabilidade , Vapor , Temperatura , Resistência à TraçãoRESUMO
This paper reports the characterization of polyvinyl alcohol (PVA)/cassava starch biocomposites. The cassava starch gel with or without ultrasonic probe treatment was mixed with PVA gel then short bacterial cellulose fibers were added. The presence of the sonicated starch gel in the PVA resulted in low thermal and moisture resistance, and low transparency of the blend film. After adding the fibers thermal and moisture resistance of the sonicated biocomposite increased due to stronger hydrogen bonding between the fibers and the matrix. Tensile strength of sonicated biocomposite with 10 g fibers increased 215% compared to the sonicated blend. However, addition of the fibers to the non-sonicated blend did not significantly increase mechanical and thermal properties or moisture resistance of the biocomposite. Opacity of the non-sonicated biocomposite was lower than that of the sonicated one.
RESUMO
As more applications for nano-sized natural particles are discovered, simple, environmentally friendly ways to produce these particles become more important. This work prepares and characterizes nano-size bacterial cellulose particles using ultrasonication. Pellicle from nata de coco containing nanofibers was broken up in an electrical blender, then sonicated using an ultrasonic probe at 20â¯kHz and 3â¯W/mL for 30, 60 and 90â¯min. Transmission electron microscope observations indicate the particles become nano-sized after 60â¯min ultrasound. The maximum decomposition temperature before sonication was 373⯰C, decreased to 357⯰C after 60â¯min ultrasonication. Moisture absorption of the 90â¯min sonicated particles film is 60% slower compared to non-sonicated particles. After ultrasonication, the crystallinity index of the cellulose decreases. The functional groups of non-sonicated and sonicated cellulose remain the same. This study promotes a potential method of fabrication of nano-sized particles from pure bacterial cellulose.
RESUMO
This paper reported the results of the characterization of jicama (Pachyrhizus erosus) starch based biocomposite reinforced with varied nanofiber fractions, i.e. 35.4, 70.8 and 106.2⯵g per 10â¯g of starch. The nanofiber was isolated from oil palm empty fruit bunches. During preparation, the biocomposite in form of gel was sonicated using an ultrasonic probe at various powers, i.e. 0, 480, 600, 720 watt at 20â¯kHz for 5â¯min. The results show that ultrasonication results in a significant improvement in biocomposite properties for each of the nanofiber fractions. The tensile strength, moisture resistance of the 35.4⯵g nanofibers biocomposite increase significantly 278, 11% respectively after 600 watt ultrasonication. Field emission scanning electron microscopy of the fracture surface of the film showed ultrasonication resulted in it becoming smoother and more compact. These results indicate that ultrasonication improves the performance of the film.