Ultrasonic Synthesis of Nanochitosan and Its Size Effects on Turbidity Removal and Dealkalization in Wastewater Treatment

Acute Phytotoxicity and Antifungal Effect of Nanochitosan Particles on Colletotrichum fructicola with Low Susceptibility to Chitosan

Colletotrichum fungus complex affects several crops and tropical products, which suffer significant losses due to anthracnose. The use of chitosan nanoparticles (CNPs), alone or in combination with bioactive compounds, has been recommend for agronomic applications. However, there is very little information on their phytotoxicity, and there is no information about the effect on microorganisms with low susceptibility to chitosan. This work aims to compare their antifungal effect against isolates of C. fructicola with low susceptibility to chitosan and to study the toxicological effects of CNPs on the germination of lettuce (Lactuca sativa) and radish (Raphanus sativus) seeds. Levels of phytotoxicity of high-to-very high and moderate-to-very high were observed for lettuce and radish seeds, respectively, with greater detrimental effects on the radicle elongation after exposure to CNPs concentrations of 4-5 g L-1. For the three C. fructicola isolates, the CNPs did not inhibit the fungal growth; however, the cell viability decreased as the CNPs concentration increased, and a complete inhibition of the viability was found for H4-1 and 003 isolates at a CNPs concentration of 5 g L-1. Morphometric alterations characterized by a reduction in the average length of the terminal hyphae, distortion, and a higher number of branches in the hyphae, were observed. To our knowledge, this is the first report where the effect of nanochitosan particles in Colletotrichum fructicola, with experimentally proven low sensitivity to chitosan, was studied.

Novel algae-mediated biosynthesis approach of chitosan nanoparticles using Ulva fasciata extract, process optimization, characterization and their flocculation performance

Chitosan nanoparticles (CNPs) are promising biopolymeric nanoparticles with excellent physicochemical, antimicrobial, and biological properties. In this investigation, CNPs were produced using Ulva fasciata biomass extract as a reducing agent. The SEM micrograph revealed that the biosynthesized CNPs appeared to be spheres with a mean size of 32.49 nm. The ζ-potential pattern of CNPs has a single peak at +33.1 mV, indicating a positively charged surface. The X-ray diffraction pattern of the biosynthesized CNPs exhibited three different peaks at 2θ = 25.24, 52.96, and 72.28°. The FTIR analysis identifies various functional groups. The thermogravimetric analyses demonstrate that CNPs have high thermal stability. Additionally, the highest biosynthesis of CNPs (8.96 mg CNPs/mL) was obtained via FCCD when the initial pH level was 4, Ulva fasciata extract concentration was 45 %, v/v, and chitosan concentration was 0.9 %. Algae-mediated synthesized CNPs were used as coagulating/flocculating agents. By using the jar test, CNPs exhibited superior flocculation performance compared to commercial coagulants like alum, FeCl3, and chitosan in bulk form. Further, different parameters were screened, and the maximum flocculating activity (FA) recorded was 83.58 ± 0.47 % at 500 mg/L of CNPs, 1-5 % clay suspension at pH and temperature ranges of 6-8 and 10-80 °C, respectively. CNPs displayed eminent performance in water clarification.

Nanoparticle-mediated dsRNA delivery for precision insect pest control: a comprehensive review

Nanoparticle-based delivery systems have emerged as powerful tools in the field of pest management, offering precise and effective means of delivering double-stranded RNA (dsRNA), a potent agent for pest control through RNA interference (RNAi). This comprehensive review aims to evaluate and compare various types of nanoparticles for their suitability in dsRNA delivery for pest management applications. The review begins by examining the unique properties and advantages of different nanoparticle materials, including clay, chitosan, liposomes, carbon, gold and silica. Each material's ability to protect dsRNA from degradation and its potential for targeted delivery to pests are assessed. Furthermore, this review delves into the surface modification strategies employed to enhance dsRNA delivery efficiency. Functionalization with oligonucleotides, lipids, polymers, proteins and peptides is discussed in detail, highlighting their role in improving stability, cellular uptake, and specificity of dsRNA delivery.This review also provides valuable guidance on choosing the most suitable nanoparticle-based system for delivering dsRNA effectively and sustainably in pest management. Moreover, it identifies existing knowledge gaps and proposes potential research directions aimed at enhancing pest control strategies through the utilization of nanoparticles and dsRNA.

Efficiency of chitosan nanoparticle with polyaluminum chloride in dye removal from aqueous solutions: Optimization through response surface methodology (RSM) and central composite design (CCD)

According to the widespread use of polyaluminum chloride (PAC) in wastewater treatment and residual aluminum left in treated water, there is an urgent need to use environmentally friendly natural coagulants with conventional chemical coagulants to reduce their consumption. In this investigation, chitosan (CS) nanoparticles prepared as natural coagulant by ion gelation were applied to remove anionic dyes from aqueous solutions. For the characterization of the synthesized CS nanoparticles, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and zeta analyzer were used. The effects of different parameters, including pH, initial concentration of dye in addition to CS nanoparticles, and PAC dosages on adsorption efficiency were studied via response surface methodology (RSM) to determine the optimum conditions for maximum color removal. Results of the tests indicate that the use of CS nanoparticles and PAC with an interval of 30 s effectively increases the efficiency of color removal. The usage of PAC (80 mg/L) and CS nanoparticles (150 mL/L) at pH = 6.6 reaches the maximum color removal efficiency of 92 %. Accordingly, the use of CS nanoparticles as coagulant aid reduced the amount of needed PAC and enhanced the color removal efficiency. Furthermore, the exclusive effect of CS nanoparticles in the adsorption of dye revealed that the adsorption followed the Langmuir type II model, with an adsorption capacity of 1100 mg/g. The resulting data from the kinetic study indicated that the pseudo-second-order type II model was the most suitable model to describe the adsorption process of dye on CS nanoparticles. Based on the results, the CS nanoparticles have adequate potential to reduce the amount of needed PAC dosage for the treatment of water contaminated with anionic dyes.

Characterization and antimicrobial activity of a chitosan-selenium nanocomposite biosynthesized using Posidonia oceanica

Nanobiotechnological approaches can provide effective solutions for overcoming food products' contamination and spoilage. The development of rapid and eco-friendly approaches for synthesizing nanocomposites from chitosan nanoparticles (Cht), Neptune grass "Posidonia oceanica" extract (NG), and NG-mediated selenium nanoparticles (SeNPs) was targeted, with their investigation as potential antimicrobial, antioxidant, and biopreservatives of fresh chicken fillets. SeNPs were biosynthesized with NG, and their conjugates with Cht were composited. Characterization approaches, including infrared analysis, physiognomic analysis, and electron microscopy of synthesized nanomaterials and composites, were applied. The nanomaterials' antibacterial properties were assessed against Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli qualitatively, quantitatively, and with ultrastructure imaging. The antimicrobial and antioxidant potentialities of nanomaterials were employed for preserving chicken fillets, and the sensorial and microbiological parameters were assessed for coated fillets. SeNPs were effectively biosynthesized by NG, with mean diameters of 12.41 nm; the NG/SeNPs had homogenous spherical shapes with good distribution. The prepared Cht/NG/SeNPs nanoconjugates had a mean diameter of 164.61 nm, semi-spherical or smooth structures, and charges of +21.5 mV. The infrared analyses revealed the involvement of biochemical groups in nanomaterial biosynthesis and interactions. The antibacterial actions of nanomaterials were proven against the entire challenged strains; Cht/NG/SeNPs was the most active agent, and Salmonella typhimurium was the most susceptible bacteria. Scanning micrographs of Cht/NG/SeNPs-treated Staphylococcus aureus and Salmonella typhimurium indicate the severe time-dependent destruction of bacterial cells within 8 h of exposure. The antioxidant potentiality of Cht/NG/SeNPs was the highest (91.36%), followed by NG/SeNPs (79.45%). The chicken fillets' coating with Cht, NG, NG/SeNPs, and Cht/NG/SeNPs resulted in a remarkable reduction in microbial group count and raised the sensorial attributes of coated fillets after 14 days of cold storage, with increased potentialities in the order: Cht/NG/SeNPs > NG/SeNPs > NG > Cht > control. The inventive, facile biosynthesis of Cht, NG, and SeNPs could provide effective antimicrobial and antioxidant nanocomposites for prospective applications in food biopreservation.

Chitosan-Based Formulations Intended as Protective Spray for Mask Surfaces in Prevention of Coronavirus Dissemination

The extraordinary occurrence of COVID-19 by the fast expansion of viral infections has propelled particular interest in developing novel antiviral and virucidal agents to guarantee personal security. The main objective of this work is to propose novel formulations able to optimize the use of personal protection elements. In recent years, chitosan (CH) has attracted attention for being an interesting multifunctional, biodegradable, non-antigenic, non-toxic, and biocompatible natural polymer with antimicrobial properties. In this work, formulations based on a CH matrix containing silver, and Copper based nanoparticles have been developed. The novelty of this proposal is that almost liquid formulations have been reached, possessing verified properties to inhibit evolved virus such as herpes simplex type 1 (HSV-1) and bovine betacoronavirus (BCoV), the latter belonging to the same family of the well-known the well-known SARS-CoV-2. Besides antibacterial bioactivity; as well as the ability of these formulations to be easily sprayed on various surfaces, including conventional face masks, have been verified and discussed. The results presented in this contribution provide strong evidence on CH films as an ideal biosafe surface-protective for several daily used materials including the conventional face masks.