Tropical sharks feasting on and swimming through microplastics: First evidence from Malaysia.

Plastic can be degraded into microplastic (<5 mm) and has been polluting worldwide marine environment and negatively impact human health. Microplastics in marine organisms are still understudied in Malaysia, let alone from a subclass Elasmobranchii. Five tropical shark species (Carcharhinus dussumieri, Carcharhinus sorrah, Chiloscyllium hasseltii, Chiloscyllium punctatum, and Scoliodon laticaudus) were examined for the presence of microplastics. 74 sharks were sampled from the local wet market and 100 % of samples contained microplastics. A total of 2211 plastic particles were found in gastrointestinal tracts (GIT) and gills, where 29.88 ± 2.34 particles per shark (mean ± SEM). Black (40.07 %) and fiber (84.44 %) microplastics were the most dominant. Extracted microplastic sizes ranged from 0.007 mm to 4.992 mm. This study suggests that microplastic uptake is gender-related for some shark species. A subsample of microplastics (10 %) was used for polymer type identification, where polyester was recorded the highest (43.95 %).

Occurrence, distribution and characteristics of microplastics in gastrointestinal tract and gills of commercial marine fish from Malaysia.

Microplastics are tiny plastic particles with size below 5 mm, prevalence in marine environments and the occurrence have been reported in commercial marine fish worldwide. Microplastics' abilities to absorb various marine contaminants raised considerable concern on their role as a vector to spread harmful pollutants to the alienated environment. This study focussed on the occurrence of microplastics in gastrointestinal tract (GIT) and gills of 158 fishes across 16 species from two locations in Malaysia coastal waters. Microplastics were detected approximately 86% in the GIT and 92% in the gills of examined fish. High incident of microplastics was detected in fishes from the area that is close to an urban area with average microplastics incident reaching up to 9.88 plastics items/individuals. Meanwhile, only 5.17 microplastics per individual were recorded in fishes from a less urbanised area. Isolated microplastics comprised 80.2% of fibres, 17.7% of fragments and the remaining was derived from filaments (3.1%). Infrared and Raman spectroscopy analysis of selected microplastics revealed the chemical composition of microplastics which comprised of polyethene (PE), polypropylene (PP), acrylonitrile butadiene styrene (ABS), polystyrene (PS) and polyethylene terephthalates (PET). FESEM images indicate, different surface characteristics of microplastics as a result of environmental exposure. Further, elemental analysis using EDX for green PE fragments showed the uneven distribution of chromium (Cr) and iron (Fe) on the surface, suggesting the adherence of heavy metals on the surface of microplastics. Overall findings indicate the widespread distribution of microplastics in commercial marine fishes from Malaysia waters and could potentially lead to human exposure through fish consumption.

Sago starch nanocrystal-stabilized Pickering emulsions: Stability and rheological behavior.

This study presents the isolation of SNC from sago starch and its performance as proficient particle emulsifier. It highlights the impact of SNC on the stability and rheological properties of oil-in-water (o/w) emulsions. The percentage yield of the SNC obtained was equivalent to 25 ± 0.1% (w/w) with particle diameters ranging from 25 to 100 nm. A series of Pickering emulsion at different ratios of oil (5%-35% v/v) and SNC (1%-4% w/v) was prepared for further investigations. The mean droplet diameter of emulsions obtained was ranged from 19.12 to 35.96 µm, confirming the effects of both SNC and oil content on the droplet's diameter distribution. Formulations with 4.0 wt% of SNC exhibited the maximum stability against coalescence. Results obtained have justified that the SNC can be used as an alternative solid emulsifier in producing stable emulsion with desired properties for various applications.

Improving the efficiency of post-digestion method in extracting microplastics from gastrointestinal tract and gills of fish.

Post-digestion treatment is an important step during sample preparation to facilitate the removal of undigested materials for better detection of ingested microplastics. Sieving, density separation with zinc chloride solution (ZnCl2), and oil extraction protocol (OEP) have been introduced in separating microplastics from sediments. The clean-up methods are rarely highlighted in previous studies, especially in the separation of microplastics from marine biota. Thus, this study proposed and compared the suitability of three techniques, which can reduce the number of undigested particles from the digestate of GIT and gills. Our result has shown excellent removal of non-plastics materials and reduces the coloration of filter paper in all treated samples. Both sieving and density separation achieved optimum post-digestion efficiencies of >95% for both GIT and gill samples, which former showed no effect on polymer integrity. Additionally, high recovery rate was obtained for the larger size microplastics (>500 µm) with approximately 97.7% (GIT) and 95.7% (gill), respectively. Exposure to the ZnCl2 solution led to a significant loss of smaller size PET and changed the absorption spectrums of all tested polymers. Particle morphology determined by SEM revealed such exposure eroded the surface of PET fragments and elemental analysis has shown detectable peaks of zinc and chlorine appeared. Low microplastics recoveries were achieved through OPE and residue of oil was observed from the infrared spectrum of all tested polymer. The findings demonstrate sieving with size fractioning can provide exceptional removal of non-plastics materials from the digestate of GIT and gill samples.

Comprehensive spectroscopic studies of synergism between Gadong starch based carbon dots and bovine serum albumin.

Carbon dots (C-dots) were used to study the binding mechanisms with serum protein, bovine serum albumin (BSA) by using two notable binding systems known as non-covalent and covalent interaction. Interaction between C-dots and BSA were estimated by Stern-Volmer equation and Double Log Regression Model (DLRM). According to the fluorescent intensity, quenching of model carrier protein by C-dots was due to dynamic quenching for non-covalent and static quenching for covalent binding. The binding site constant, KA and number of binding site, for covalent interaction is 1754.7L/mol and n≈1 (0.6922) were determined by DLRM on fluorescence quenching results. The blue shift of the fluorescence spectrum, from 450nm to 421nm (non-covalent) and 430nm (covalent) and suggested that both the microenvironment of C-dots and protein changed in relation to the protein concentration. The fluorescence intensity results show that protein structure has a significant role in Protein-C-dots interactions and type of binding influence physicochemical properties of C-dots differently. Understanding to this bio interface is important to utilize both quantum dots and biomolecules for biomedical field. It can be a useful guideline to design further applications in biomedical and bioimaging.

Cytotoxicity and Toxicity Evaluation of Xanthone Crude Extract on Hypoxic Human Hepatocellular Carcinoma and Zebrafish (Danio rerio) Embryos.

Xanthone is an organic compound mostly found in mangosteen pericarp and widely known for its anti-proliferating effect on cancer cells. In this study, we evaluated the effects of xanthone crude extract (XCE) and α-mangostin (α-MG) on normoxic and hypoxic human hepatocellular carcinoma (HepG2) cells and their toxicity towards zebrafish embryos. XCE was isolated using a mixture of acetone and water (80:20) and verified via high performance liquid chromatography (HPLC). Both XCE and α-MG showed higher anti-proliferation effects on normoxic HepG2 cells compared to the control drug, 5-fluorouracil (IC50 = 50.23 ± 1.38, 8.39 ± 0.14, and 143.75 ± 15.31 µg/mL, respectively). In hypoxic conditions, HepG2 cells were two times less sensitive towards XCE compared to normoxic HepG2 cells (IC50 = 109.38 ± 1.80 µg/mL) and three times less sensitive when treated with >500 µg/mL 5-fluorouracil (5-FU). A similar trend was seen with the α-MG treatment on hypoxic HepG2 cells (IC50 = 10.11 ± 0.05 µg/mL) compared to normoxic HepG2 cells. However, at a concentration of 12.5 µg/mL, the α-MG treatment caused tail-bend deformities in surviving zebrafish embryos, while no malformation was observed when embryos were exposed to XCE and 5-FU treatments. Our study suggests that both XCE and α-MG are capable of inhibiting HepG2 cell proliferation during normoxic and hypoxic conditions, more effectively than 5-FU. However, XCE is the preferred option as no malformation was observed in surviving zebrafish embryos and it is more cost efficient than α-MG.

Methylene blue removal by using pectin-based hydrogels extracted from dragon fruit peel waste using gamma and microwave radiation polymerization techniques.

This research aims to compare the ability of smart hydrogel in removing the methylene blue prepared by using two different radiation methods. The extracted pectin from the dragon fruit peel (Hylocereus polyrhizus) was used with acrylic acid (AA) to produce a polymerized hydrogel through gamma and microwave radiation. The optimum hydrogel swelling capacity was obtained by varying the dose of radiation, pectin to AA ratio and pH used. From the array of samples, the ideal hydrogel was obtained at pH 8 with a ratio of 2:3 (pectin: AA) using 10 kGy and 400 W radiated gamma and microwave respectively. The performance of both hydrogels namely as Pc/AA(G) (gamma) and Pc/AA(Mw) (microwave) were investigated using methylene blue (MB) adsorption studies. In this study, three variables were manipulated, pH and MB concentration and hydrogel mass in order to find the optimum condition for the adsorption. Results showed that 20 mg of Pc/AA(G) performed the highest MB removal which was about 45% of 20 mg/L MB at pH 8. While 30 mg of Pc/AA(Mw) able to remove up to 35% of 20 mg/L MB at the same pH condition. To describe the adsorption mechanism, both kinetic models pseudo-first-order, pseudo-second-order were employed. The results from kinetic data showed that it fitted the pseudo-first-order as compared to pseudo-second-order model equation. This study provides alternative of green, facile and affective biomaterial for dye absorbents that readily available.

Modified Dioscorea hispida starch-based hydrogels and their in-vitro cytotoxicity study on small intestine cell line (FHS-74 Int).

Starch-based hydrogels are promising smart materials for biomedical and pharmaceutical applications, which offer exciting perspectives in biophysical research at molecular level. This work was intended to develop, characterize and explore the properties of hydrogel from starch extracted from new source, Dioscorea hispida Dennst. Starch-mediated hydrogels were successfully synthesized via free radical polymerization method with varying concentrations of acrylic acid (AA),N,N'-methylenebisacrylamide (MBA) and sodium hydroxide (NaOH) in aqueous system. The grafting reaction between starch and AA was examined by observing the decline in intensity peak of hydrogel FTIR spectrum at 3291cm-1 and peak around 1600-1680cm-1, indicating the stretching of hydroxyl group (OH) and stretching of carbon-carbon double bond (CC) respectively. The effects of cross-linker, monomer and NaOH concentration on swelling ratio and gel content in different medium and conditions were also evaluated. The thermal stability and structural morphology of as-synthesized hydrogels were studied by thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). In-vitro cytotoxicity study using small intestine cell line (FHS-74 Int) revealed that the as-formulated eco-friendly-hydrogel was free from any harmful material and safe to use for future product development.

Varieties, production, composition and health benefits of vinegars: A review.

Vinegars are liquid products produced from the alcoholic and subsequent acetous fermentation of carbohydrate sources. They have been used as remedies in many cultures and have been reported to provide beneficial health effects when consumed regularly. Such benefits are due to various types of polyphenols, micronutrients and other bioactive compounds found in vinegars that contribute to their pharmacological effects, among them, antimicrobial, antidiabetic, antioxidative, antiobesity and antihypertensive effects. There are many types of vinegars worldwide, including black vinegar, rice vinegar, balsamic vinegar and white wine vinegar. All these vinegars are produced using different raw materials, yeast strains and fermentation procedures, thus giving them their own unique tastes and flavours. The main volatile compound in vinegar is acetic acid, which gives vinegar its strong, sour aroma and flavour. Other volatile compounds present in vinegars are mainly alcohols, acids, esters, aldehydes and ketones. The diversity of vinegars allows extensive applications in food.

Physicochemical Properties of Starch from Dioscorea pyrifolia tubers.

Starch from Dioscorea pyrifolia tubers was characterized for its proximate composition, physicochemical properties and toxicity. This starch contains 44.47±1.86% amylose, 4.84±0.29% moisture, 0.88±0.21% ash, 1.34±0.11% proteins and 92.73±0.48% carbohydrates. X-ray diffraction (XRD) analysis showed a type-C starch with a relative crystallinity of 23.31±2.41%. The starch granules are polyhedral, with a diameter of 2.8 to 5.6µm and average size of 3.93±1.47µm. Initial, peak and finishing gelatinization temperatures for the starch were 71.51±0.07, 75.05±0.15, and 78.25±0.18°C, respectively; the gelatinization enthalpy was 3.86±0.02J/g, and the peak height index was 1.09±0.05. Thermogravimetric analysis showed a weight loss of 85.81±0.52% and a decomposition temperature of 320.16±0.35°C, which indicated that there was good thermal stability of the starch. Fish embryo toxicity (FET) showed that the starch was not toxic and that it was suitable for food and non-food industries.

Transformation of crystalline starch nanoparticles into highly luminescent carbon nanodots: Toxicity studies and their applications.

Being abundant in many tropical part of the world, Dioscorea sp. as food is limited due to its toxicity. However polysaccharides derive from these tubers could be important for other applications. Here we developed a Highly Luminescent Carbon Nanodots (C-dots) via acid hydrolysis of Gadong starch (GS). The hydrolysis rate of GS increased from 49% to 86% within 7 days while the X-ray diffraction showed the native GS particle is a C-crystalline type. The GS particles were either round or oval with diameters ranging from 50-90 nm. Further acid dehydration and surface oxidation reduced the size of GS nanoparticles to 6-25 nm. The C-dots produced a fluorescent emission at wavelength 441 nm. Toxicity tests demonstrate that zebrafish embryo were able to tolerate the C-dots for 48 h after exposure. This study has successfully demonstrated a novel approach of converting GS into excellent fluorescent C-dot.

Synthesis of a novel acrylated abietic acid-g-bacterial cellulose hydrogel by gamma irradiation.

Acrylated abietic acid (acrylated AbA) and acrylated abietic acid-grafted bacterial cellulose pH sensitive hydrogel (acrylated AbA-g-BC) were prepared by a one-pot synthesis. The successful dimerization of acrylic acid (AA) and abietic acid (AbA) and grafting of the dimer onto bacterial cellulose (BC) was confirmed by 13C solid state NMR as well as FT-IR. X-ray diffraction analysis showed characteristic peaks for AbA and BC; further, there was no effect of increasing amorphous AA content on the overall crystallinity of the hydrogel. Differential scanning calorimetry revealed a glass transition temperature of 80°C. Gel fraction and swelling studies gave insight into the features of the hydrogel, suggesting that it was suitable for future applications such as drug delivery. Scanning electron microscopy observations showed an interesting interpenetrating network within the walls of hydrogel samples with the lowest levels of AA and gamma radiation doses. Cell viability test revealed that the synthesized hydrogel is safe for future use in biomedical applications.

Controlling gold nanoparticle stability with triggerable microgels.

The interaction of a photodegradable surfactant (PS, 4-hexylphenylazosulfonate, C(6)PAS) with microgels (MGs) of poly(2-vinyl pyridine) (MGA) in the protonated state (pH 3) has been investigated. Electrophoretic mobility measurements confirm that negatively charged PS interacts with positively charged MGA to form mixed PS-MG complexes. This was sensed by a decrease in the effective PS-MGA charge and a switch in sign of electrophoretic mobility, from positive to negative, with increasing PS concentration. After the addition of extra positive microgels (MGB), the system undergoes coflocculation. Incident UV irradiation was used to photolyze the anionic PS, effectively eliminating the headgroups, thereby lowering the electrostatic interactions between PS and MGA microgel networks. Consequently, a reversal of MGA charge occurred, leading to electrostatic repulsions and causing the MGs to reswell and redisperse, with both MGA and MGB now being positively charged and hence stabilized against coflocculation. Extending this approach, negatively charged gold nanoparticles (AuMES) have been incorporated into the PS-MGA complexes. Atomic absorption spectroscopy (AAS) showed that 100% of the AuMES particles were recovered after coflocculation of (PS-MGA)-AuMES complexes with MGB. Furthermore, approximately 75% of the AuMES could be redispersed after UV irradiation to restabilize the dispersion. This system provides an interesting method for phase separation and gold nanoparticle recovery for reuse and recycling.