1,3,5-Triazine-2,4,6-tribenzaldehyde derivative as a new crosslinking agent for synthesis of pH-thermo dual responsive chitosan hydrogels and their nanocomposites: Swelling properties and drug release behavior

The Use and Impact of Antibiotics in Plant Agriculture: A Review

Growers have depended on the specificity and efficacy of streptomycin and oxytetracycline as a part of their plant disease arsenal since the middle of the 20th century. With climate change intensifying plant bacterial epidemics, the established success of these antibiotics remains threatened. Our strong reliance on certain antibiotics for devastating diseases eventually gave way to resistance development. Although antibiotics in plant agriculture equal to less than 0.5% of overall antibiotic use in the United States, it is still imperative for humans to continue to monitor usage, environmental residues, and resistance in bacterial populations. This review provides an overview of the history and use, resistance and mitigation, regulation, environmental impact, and economics of antibiotics in plant agriculture. Bacterial issues, such as the ongoing Huanglongbing (citrus greening) epidemic in Florida citrus production, may need antibiotics for adequate control. Therefore, preserving the efficacy of our current antibiotics by utilizing more targeted application methods, such as trunk injection, should be a major focus. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Preparation of a modified silk-based gel/microsphere composite as a potential hepatic arterial embolization agent

Transcatheter arterial chemoembolization (TACE) is an effective method for treating hepatocellular carcinoma (HCC). In this study, chitosan (CS), sodium glycerophosphate (GP), and sodium alginate (SA) were used as the main raw materials to develop clinically non-degradable embolization microspheres (Ms). Chitosan/sodium alginate embolization Ms. were generated using an emulsification cross-linking method. The Ms. were then uniformly dispersed in CS/GP temperature-sensitive gels to produce Gel/Ms. composite embolic agents. The results showed that Gel/Ms. had good morphology and a neatly arranged three-dimensional structure, and the Ms. dispersed in the Gel as evidenced by SEM. Furthermore, Gel/Ms. has good blood compatibility, with a hemolysis rate of ≤5 %. The cytotoxicity experiments have also proven its excellent cell compatibility. The degradation rate of Gel/Ms. was 58.869 ± 1.754 % within 4 weeks, indicating that Gel/Ms. had good degradation performance matching its drug release purpose. The Gel/Ms. adheres better at the target site than Ms. alone and releases the drug steadily over a long period, and the maximum release rate of Gel/Ms. within 8 h was 38.33 ± 1.528 %, and within 168 h was 81.266 ± 1.193 %. Overall, Gel/Ms. demonstrate better slow drug release, reduced sudden drug release, prolonged drug action time at the target site, and reduced toxic side effects on the body compared to Gel alone.

Customizing nano-chitosan for sustainable drug delivery

Chitosan is a natural polymer with acceptable biocompatibility, biodegradability, and mechanical stability; hence, it has been widely appraised for drug and gene delivery applications. However, there has been no comprehensive assessment to tailor-make chitosan cross-linkers of various types and functionalities as well as complex chitosan-based semi- and full-interpenetrating networks for drug delivery systems (DDSs). Herein, various fabrication methods developed for chitosan hydrogels are deliberated, including chitosan crosslinking with and without diverse cross-linkers. Tripolyphosphate, genipin and multi-functional aldehydes, carboxylic acids, and epoxides are common cross-linkers used in developing biomedical chitosan for DDSs. Methods deployed for modifying the properties and performance of chitosan hydrogels, via their composite production (semi- and full-interpenetrating networks), are also cogitated here. In addition, recent advances in the fabrication of advanced chitosan hydrogels for drug delivery applications such as oral drug delivery, transdermal drug delivery, and cancer therapy are discussed. Lastly, thoughts on what is needed for the chitosan field to continue to grow is also debated in this comprehensive review article.

Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment

The systemic drug has historically been preferred for the treatment of the majority of pathological conditions, particularly liver cancer. Indeed, this mode of treatment is associated with adverse reactions, toxicity, off-target accumulation, and rapid hepatic and renal clearance. Numerous efforts have been made to design systemic therapeutic carriers to improve retention while decreasing side effects and clearance. Following systemic medication, local administration of therapeutic agents allows for higher 'effective' doses with fewer side effects, kidney accumulation, and clearance. Hydrogels are highly biocompatible and can be used for both imaging and therapy. Hydrogel-based drug delivery approach has fewer side effects than traditional chemotherapy and can deliver drugs to tumors for a longer time. The chemical and physical flexibility of hydrogels can be used to achieve disease-induced in situ accumulation as well as subsequent drug release and hydrogel-programmed degradation. Moreover, they can act as a biocompatible depot for localized chemotherapy when stimuli-responsive carriers are administrated. Herein, we summarize the design strategies of various hydrogels used for localized chemotherapy of liver cancer and their delivery routes, as well as recent research on smart hydrogels.

Injectable Nanocomposite Hydrogels for Cancer Therapy

Hydrogel is a kind of 3D polymer network with strong swelling ability in water and appropriate mechanical and biological properties, which make it feasible to maintain bioactive substances and has promising applications in the fields of biomaterials, soft machines, and artificial tissues. Unfortunately, traditional hydrogels prepared by chemical crosslinking have poor mechanical properties and limited functions, which limit their further application. In recent years, with the continuous development of nanoparticle research, more and more studies have combined nanoparticles with hydrogels to make up for the shortcomings of traditional hydrogels. In this article, the types and functions of hydrogels and nanomaterials are introduced first, as well as the functions and applications of injectable nanocomposite hydrogels (INHs), then the latest progress of INHs for cancer treatment is reviewed, some existing problems are summarized, and the application prospect of NHs is prospected.

Anti-bacterial dynamic hydrogels prepared from O-carboxymethyl chitosan by dual imine bond crosslinking for biomedical applications

Imine dynamic hydrogels are synthesized via dual-imine bond crosslinking from O-carboxymethyl chitosan (CMCS) and a water soluble dynamer using a 'green' approach. Three dynamers are prepared through reaction of benzene-1,3,5-tricarbaldehyde and di-amino Jeffamine with molar mass of 500, 800 and 1900, respectively. Hydrogels, namely H500, H800 and H1900 are then obtained by mixing CMCS and dynamer aqueous solutions. FT-IR confirms the formation of hydrogels via imine bonding. H1900 presents larger pore size and higher storage modulus as compared to H500 and H800 due to the higher molar mass of Jeffamine linker. The hydrogels exhibit pH sensitive swelling behavior due to electrostatic attraction or repulsion in the pH range from 3 to 10. The highest swelling ratio is obtained at pH 8, reaching 7500% for H800. Self-healing of hydrogels is evidenced by rheological measurements with alternatively applied low and high strains, and by using a macroscopic approach with re-integration of injected filaments. Furthermore, the H1900 membrane exhibits outstanding antibacterial activity against an E. coli suspension at 10⁸ CFU mL^-1. Therefore, dynamic hydrogels synthesized from CMCS and Jeffamine present outstanding rheological, swelling, self-healing and antibacterial properties, and are most promising as healthcare material in wound dressing, drug delivery and tissue engineering.

Design of nanostructure chitosan hydrogels for carrying zinc phthalocyanine as a photosensitizer and difloxacin as an antibacterial agent

Here, we develop homogeneous hydrogel networks containing zinc tetraamino-phthalocyanine (ZnTAPc) as photosensitizer cross-linked with glutaraldehyde. The cross-linking process occurs via imine bond formation by reaction of NH₂ groups of ZnTAPc and chitosan with aldehyde groups of the glutaraldehyde. Insertion of ZnTAPc interestingly increases its solubility in water medium. 2.0% and 4% w/w of the ZnTAPc were used with respect to chitosan polymer to generate hydrogel photosensitizer. FT-IR and UV-Vis spectroscopy, scanning electron microscopy, and rheological measurements were applied to evaluate the properties of the prepared hydrogels. Finally, difloxacin HCl was selected as a fluoroquinolone drug for the assessment of the drug release features of the made hydrogels. The difloxacin release was affected by the amount of ZnTAPc and pH medium. The activity of the hydrogels in photosensitizing process was considered by computing the rate of 1,3-diphenylisobenzofuran adsorption reduction as a singlet oxygen chemical quencher.

Evaluation of baiting fipronil-loaded silica nanocapsules against termite colonies in fields

Various pesticide nanocarriers have been developed. However, their pest-control applications remain limited in laboratories. Herein, we developed silica nanocapsules encapsulating fipronil (SNC) and their engineered form, poly(ethyleneimine)-coated SNC (SNC-PEI), based on recombinant catalytic modular protein D4S2 and used them against termite colonies Coptotermes lacteus in fields. To achieve this, an integrated biomolecular bioprocess was developed to produce D4S2 for manufacturing SNC containing fipronil with high encapsulation efficiency of approximately 97% at benign reaction conditions and at scales sufficient for the field applications. PEI coating was achieved via electrostatic interactions to yield SNC-PEI with a slower release of fipronil than SNC without coating. As a proof-of-concept, bait toxicants containing varied fipronil concentrations were formulated and exposed to nine termite mounds, aiming to prolong fipronil release hence allowing sufficient time for termites to relocate the baits into and distribute throughout the colony, and to eliminate that colony. Some baits were relocated into the mounds, but colonies were not eliminated due to several reasons. We caution others interested in producing bait toxicants to be aware of the multilevel resistance mechanisms of the Coptotermes spp. "superorganism".

Nano-based smart pesticide formulations: Emerging opportunities for agriculture

The incorporation of nanotechnology as a means for nanopesticides is in the early stage of development. The main idea behind this incorporation is to lower the indiscriminate use of conventional pesticides to be in line with safe environmental applications. Nanoencapsulated pesticides can provide controlled release kinetics, while efficiently enhancing permeability, stability, and solubility. Nanoencapsulation can enhance the pest-control efficiency over extended durations by preventing the premature degradation of active ingredients (AIs) under harsh environmental conditions. This review is thus organized to critically assess the significant role of nanotechnology for encapsulation of AIs for pesticides. The smart delivery of pesticides is essential to reduce the dosage of AIs with enhanced efficacy and to overcome pesticide loss (e.g., due to leaching and evaporation). The future trends of pesticide nanoformulations including nanomaterials as AIs and nanoemulsions of biopesticides are also explored. This review should thus offer a valuable guide for establishing regulatory frameworks related to field applications of these nano-based pesticides in the near future.