Management and Mitigation of Vibriosis in Aquaculture: Nanoparticles as Promising Alternatives

Vibriosis is one of the most common diseases in marine aquaculture, caused by bacteria belonging to the genus Vibrio, that has been affecting many species of economically significant aquatic organisms around the world. The prevention of vibriosis in aquaculture is difficult, and the various treatments for vibriosis have their limitations. Therefore, there is an imperative need to find new alternatives. This review is based on the studies on vibriosis, specifically on the various treatments and their limitations, as well as the application of nanoparticles in aquaculture. One of the promising nanoparticles is graphene oxide (GO), which has been used in various applications, particularly in biological applications such as biosensors, drug delivery, and potential treatment for infectious diseases. GO has been shown to have anti-bacterial properties against both Gram-positive and Gram-negative bacteria, but no research has been published that emphasizes its impact on Vibrio spp. The review aims to explore the potential use of GO for treatment against vibriosis.

Short-chain fatty acids: possible regulators of insulin secretion

The benefits of gut microbiota-derived short-chain fatty acids (SCFAs) towards health and metabolism have been emerging since the past decade. Extensive studies have been carried out to understand the mechanisms responsible in initiating the functionalities of these SCFAs towards body tissues, which greatly involves the SCFA-specific receptors free fatty acid receptor 2 (FFAR2) and free fatty acid receptor 3 (FFAR3). This review intends to discuss the potential of SCFAs particularly in regulating insulin secretion in pancreatic β-cells, by explaining the production of SCFAs in the gut, the fate of each SCFAs after their production, involvement of FFAR2 and FFAR3 signalling mechanisms and their impacts on insulin secretion. Increased secretion of insulin after SCFAs treatments were reported in many studies, but contradicting evidence also exist in several other studies. Hence, no clear consensus was achieved in determining the true potential of SCFA in regulating insulin secretion. In this review, we explore how such differences were possible and hopefully be able to shed some perspectives in understanding SCFAs-signalling behaviour and preferences.

Stability, Toxicity, and Antibacterial Potential of Gallic Acid-Loaded Graphene Oxide (GAGO) Against Methicillin-Resistant Staphylococcus aureus (MRSA) Strains

Background

The impetuous usage of antibiotics has led to the perpetual rise of methicillin-resistant Staphylococcus aureus (MRSA), which has garnered the interest of potential drug alternatives, including nanomaterials.

Purpose

The present study investigates the stability, toxicity, and antibacterial potential of gallic acid-loaded graphene oxide (GAGO) on several MRSA strains.

Methods

The stability of a synthesized and characterized GAGO was monitored in different physiological media. The toxicity profile of GAGO was evaluated in 3T3 murine fibroblast cells and the embryonic zebrafish model. The antibacterial activity of GAGO against MRSA, methicillin-susceptible S. aureus (MSSA), and community-acquired MRSA; with or without Panton-valentine leucocidin gene (MRSA-pvl+ and MRSA-pvl-) was investigated through disk diffusion, CFU counting method, time-kill experiment, and high-resolution transmission electron microscopy (HRTEM) observation.

Results

A stable GAGO nanocomposite has shown an improved toxicity profile in 3T3 murine fibroblast cells and zebrafish embryos, besides exhibiting normal ROS levels than graphene oxide (GO) and GA (gallic acid). The nanocomposite inhibited the growth of all bacterial strains employed. The effectiveness of the GAGO nanocomposite was comparable to cefoxitin (CFX), at ≥150 µg/mL in MRSA and MSSA. GAGO exhibited a significantly delayed response towards MRSA-pvl+ and MRSA-pvl-, with increased inhibition following 8 to 24 h of exposure, while comparable activity to native GA was only achieved at 24 h. Meanwhile, for MRSA and MSSA, GAGO had a comparable activity with native GA and GO as early as 2 h of exposure. HRTEM observation further reveals that GAGO-exposed cells were membrane compromised.

Conclusion

In summary, the present study indicates the antibacterial potential of GAGO against MRSA strains, but further study is warranted to understand the mechanism of action of GAGO and its resistance in MRSA strains.

The Mechanistic Action of Biosynthesised Silver Nanoparticles and Its Application in Aquaculture and Livestock Industries

Nanotechnology is a rapidly developing field due to the emergence of various resistant pathogens and the failure of commercial methods of treatment. AgNPs have emerged as one of the best nanotechnology metal nanoparticles due to their large surface-to-volume ratio and success and efficiency in combating various pathogens over the years, with the biological method of synthesis being the most effective and environmentally friendly method. The primary mode of action of AgNPs against pathogens are via their cytotoxicity, which is influenced by the size and shape of the nanoparticles. The cytotoxicity of the AgNPs gives rise to various theorized mechanisms of action of AgNPs against pathogens such as activation of reactive oxygen species, attachment to cellular membranes, intracellular damage and inducing the viable but non-culturable state (VBNC) of pathogens. This review will be centred on the various theorized mechanisms of actions and its application in the aquaculture, livestock and poultry industries. The application of AgNPs in aquaculture is focused around water treatment, disease control and aquatic nutrition, and in the livestock application it is focused on livestock and poultry.

In vitro drug release characteristic and cytotoxic activity of silibinin-loaded single walled carbon nanotubes functionalized with biocompatible polymers

In this paper, we demonstrate the preparation of silibinin-loaded carbon nanotubes (SWSB) with surface coating agents via non-covalent approach as an effective drug delivery system. The resulting surface-coated SWSB nanocomposites are extensively characterized by Fourier transform infrared (FTIR) and Raman spectroscopies, ultraviolet-visible (UV-Vis) spectrometry and field emission scanning electron microscopy (FESEM). The FTIR and Raman studies show that an additional layer is formed by these coating agents in the prepared nanocomposites during the coating treatment and these results are confirmed by FESEM. Drug loading and release profiles of the coated SWSB nanocomposites in phosphate buffered saline solution at pH 7.4 is evaluated by UV-Vis spectrometry. The in vitro results indicate that the surface-modified nanocomposites, with SB loading of 45 wt%, altered the initial burst and thus, resulted in a more prolonged and sustained release of SB. In addition, these nanocomposites exhibit a pseudo-second-order release kinetic which was driven by the ion exchange between the ionized SWSB and the anions in the release medium. The cytotoxicity effect of the resulting nanocomposites on normal mouse fibroblast cells is evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. It is observed that the surfactant and polymer coating improved the biocompatibility of the SWSB nanocomposites significantly, which deem further exploitation for their application as potential anticancer drug delivery system.

Biocompatible polymers coated on carboxylated nanotubes functionalized with betulinic acid for effective drug delivery

Chemically functionalized carbon nanotubes are highly suitable and promising materials for potential biomedical applications like drug delivery due to their distinct physico-chemical characteristics and unique architecture. However, they are often associated with problems like insoluble in physiological environment and cytotoxicity issue due to impurities and catalyst residues contained in the nanotubes. On the other hand, surface coating agents play an essential role in preventing the nanoparticles from excessive agglomeration as well as providing good water dispersibility by replacing the hydrophobic surfaces of nanoparticles with hydrophilic moieties. Therefore, we have prepared four types of biopolymer-coated single walled carbon nanotubes systems functionalized with anticancer drug, betulinic acid in the presence of Tween 20, Tween 80, polyethylene glycol and chitosan as a comparative study. The Fourier transform infrared spectroscopy studies confirm the bonding of the coating molecules with the SWBA and these results were further supported by Raman spectroscopy. All chemically coated samples were found to release the drug in a slow, sustained and prolonged fashion compared to the uncoated ones, with the best fit to pseudo-second order kinetic model. The cytotoxic effects of the synthesized samples were evaluated in mouse embryonic fibroblast cells (3T3) at 24, 48 and 72 h. The in vitro results reveal that the cytotoxicity of the samples were dependent upon the drug release profiles as well as the chemical components of the surface coating agents. In general, the initial burst, drug release pattern and cytotoxicity could be well-controlled by carefully selecting the desired materials to suit different therapeutic applications.

Anticancer nanodelivery system with controlled release property based on protocatechuate-zinc layered hydroxide nanohybrid

BACKGROUND

We characterize a novel nanocomposite that acts as an efficient anticancer agent.

METHODS

This nanocomposite consists of zinc layered hydroxide intercalated with protocatechuate (an anionic form of protocatechuic acid), that has been synthesized using a direct method with zinc oxide and protocatechuic acid as precursors.

RESULTS

The resulting protocatechuic acid nanocomposite (PAN) showed a basal spacing of 12.7 Å, indicating that protocatechuate was intercalated in a monolayer arrangement, with an angle of 54° from the Z-axis between the interlayers of the zinc layered hydroxide, and an estimated drug loading of about 35.7%. PAN exhibited the properties of a mesoporous type material, with greatly enhanced thermal stability of protocatechuate as compared to its free counterpart. The presence of protocatechuate in the interlayers of the zinc layered hydroxide was further supported by Fourier transform infrared spectroscopy. Protocatechuate was released from PAN in a slow and sustained manner. This mechanism of release was well represented by a pseudo-second order kinetics model. PAN has shown increased cytotoxicity compared to the free form of protocatechuic acid in all cancer cell lines tested. Tumor growth suppression was extensive, particularly in HepG2 and HT29 cell lines.

CONCLUSION

PAN is suitable for use as a controlled release formulation, and our in vitro evidence indicates that PAN is an effective anticancer agent. PAN may have potential as a chemotherapeutic drug for human cancer.

Solubilization and binding of DNA-CTAB complex with SDS in aqueous media

Extent of binding (gamma 2(1)) of sodium dodecyl sulphate (SDS) to the binary complex formed between calfthymus DNA and cetyltrimethylammonium bromide (CTAB) has been measured in mole per mole of nucleotide in the complex as function of concentration of SDS by using equilibrium dialysis technique at different temperatures and pH. Binding of SDS to thermally denatured DNA-CTAB complex has also been studied. The most interesting aspect to be noted in this experiment is that the water insoluble DNA-CTAB binary complex gets solubilized in the ternary mixture in presence of SDS but when DNA is thermally denatured, the ternary system DNA-CTAB-SDS remains insoluble. Significant change in the extent of binding has been noted with the variation of the relative composition of DNA and CTAB in their binary mixture. The data of binding of SDS to DNA-CTAB complex are compared more precisely in terms of the standard Gibbs' free energy decrease (-delta G degree) for the saturation of the binding sites in the complex with the change of SDS activity from zero to unity in the rational mole fraction scale.

Binding of cationic surfactants to DNA, protein and DNA-protein mixtures

Extent of binding (gamma 2(1)) of cationic surfactants cetyltrimethyl ammonium bromide (CTAB), myristyltrimethyl ammonium bromide (MTAB) and dodecyl trimethyl ammonium bromide (DTAB) to calf-thymus DNA, bovine serum albumin (BSA) and to their binary mixture respectively have been measured as function of bulk concentration of the surfactant by using equilibrium dialysis technique. Binding of CTAB has been studied at different pH, ionic strength (mu), temperature and biopolymer composition and with native and denatured states of the biopolymers. The chain-length of different long chain amines plays a significant role in the extent of binding under identical solution condition. The binding ratios for CTAB to collagen, gelatin, DNA-collagen and DNA-gelatin mixtures respectively have also been determined. The conformational structures of different biopolymers are observed to play significant role in macromolecular interactions between protein and DNA in the presence of CTAB. From the experimental values of the maximum binding ratio (gamma 2m) at the saturation level for each individual biopolymer, ideal values (gamma 2m)id have been theoretically calculated for binary mixtures of biopolymers using additivity rule. The protein-DNA-CTAB interaction in mixture has been explained in terms of the deviation (delta) of (gamma 2m) from (gamma 2m)id in the presence of a surfactant in bulk. The binding of surfactants to biopolymers and to their binary mixtures are compared more precisely in terms of the Gibbs' free energy decrease (-delta G degree) for the saturation of the binding sites in the biopolymers or biopolymer mixtures with the change of the bulk surfactant activity from zero to unity in the rational mole fraction scale.