The therapeutic effect of florfenicol-loaded carboxymethyl chitosan-gelatin shell nanogels against Escherichia coli infection in mice

Gelatin/carboxymethyl chitosan/aloe juice hydrogels with skin-like endurance and quick recovery: Preparation, characterization, and properties

Gelatin-based hydrogels have gained considerable attention due to their resemblance to the extracellular matrix and hydrophilic three-dimensional network structure. Apart from providing an air-permeable and moist environment, these hydrogels optimize the inflammatory microenvironment of the wounds. These properties make gelatin-based hydrogels highly competitive in the field of wound dressings. In this study, a series of composite hydrogels were prepared using gelatin (Gel) and carboxymethyl chitosan (CMCh) as primary materials, glutaraldehyde as a crosslinker, and aloe vera juice as an anti-inflammatory component. The properties of the hydrogel, including its rheological properties, microscopic structures, mechanical properties, swelling ratios, thermal stability, antibacterial properties, and biocompatibility, were investigated. The results demonstrate that the gelatin-based hydrogels exhibit good elasticity and rapid self-healing ability. The hydrogels exhibited slight shear behavior, which is advantageous for skin care applications. Furthermore, the inclusion of aloe vera juice into the hydrogel resulted in a dense structure, improved mechanical properties and enhanced swelling ratio. The Gel/CMCh/Aloe hydrogels tolerate a compressive strength similar to that of human skin. Moreover, the hydrogels displayed excellent cytocompatibility with HFF-1 cells, and exhibited antibacterial activity against E. coli and S. aureus. Lomefloxacin was used as a model drug to study the releasing behavior of the Gel/CMCh/aloe hydrogels. The results showed that the drug was released rapidly at the initial stage, and could continue to be released for 12 h, the maximum releasing rate exceeded 20 %. These findings suggest that the gelatin-based hydrogels hold great promise as effective wound dressings.

Study on the Direct and Indirect Photolysis of Antibacterial Florfenicol in Water Using DFT/TDDFT Method and Comparison of Its Reactivity with Hydroxyl Radical under the Effect of Metal Ions

Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The focus of the study is to elucidate the direct photolysis mechanism of FLO in the water environment and the indirect photolysis of free radicals (·OH, ·NO3, and ·SO4-) as active species. The effect of metal ions Ca2+/Mg2+/Zn2+ on the indirect photolysis was also investigated. The results show that the direct photolysis of FLO involves C-C/C-N/C-S bond cleavage, the C5-S7 bond cleavage is most likely to occur, and the C17-C18 cleavage reaction is not easy to occur during the direct photodegradation of FLO. The indirect photolysis of FLO is more likely to occur in the environment than direct photolysis. The main indirect photolysis involves OH-addition, NO3-addition, and SO4-addition on benzene ring. The order of difficulty in the indirect photolysis with ·OH is C2 > C3 > C4 > C5 > C6 > C1, Ca2+ can promote the indirect photolysis with ·OH, and Mg2+/Zn2+ has a dual effect on the indirect photolysis with ·OH. In other words, Mg2+ and Zn2+ can inhibit or promote the indirect photolysis with ·OH. These studies provide important information for theoretical research on the environmental behavior and degradation mechanism of drug molecules.

Enhancement of dissolution rate and oral bioavailability of poorly soluble drug florfenicol by using solid dispersion and effervescent disintegration technology

OBJECTIVE

Florfenicol(FF) is an excellent veterinary antibiotic, limited by poor solubility and poor bioavailability.

SIGNIFICANCE

Here in, we aimed to explore the applicability of fast disintegrating tablets compressed from Florfenicol-loaded solid dispersions (FF-SD-FDTs) to improve the dissolution rate and oral bioavailability of Florfenicol.

METHODS

Utilizing selecting appropriate preparation methods and carriers, the solid dispersions of Florfenicol (FF-SDs) were prepared by solvent evaporation and the fast disintegrating tablets (FF-SD-FDTs) were prepared by the direct compression (DC) method.

RESULTS

The tablet properties including hardness, friability, disintegration time, weight variation, etc. all met the specifications of Chinese Veterinary Pharmacopeia(CVP). FF-SD-FDTs significantly improved drug dissolution and dispersion of FF in vitro compared to florfenicol conventional tablets (FF-CTs). A pharmacokinetics study in German shepherd dogs proved the AUC0-∞ and Cmax values of FF-SD-FDTs are 1.38 and 1.38 times more than FF-CTs, respectively.

CONCLUSIONS

Overall, it can be concluded that FF-SD-FDTs with excellent disintegration and dissolution properties were successfully produced, which greatly improved the oral bioavailability of the poorly soluble drug FF, and the study provided a new idea for a broader role of FF in pet clinics.

Basic concepts, recent advances, and future perspectives in the diagnosis of bovine mastitis

Mastitis is one of the most widespread infectious diseases that adversely affects the profitability of the dairy industry worldwide. Accurate diagnosis and identification of pathogens early to cull infected animals and minimize the spread of infection in herds is critical for improving treatment effects and dairy farm welfare. The major pathogens causing mastitis and pathogenesis are assessed first. The most recent and advanced strategies for detecting mastitis, including genomics and proteomics approaches, are then evaluated . Finally, the advantages and disadvantages of each technique, potential research directions, and future perspectives are reported. This review provides a theoretical basis to help veterinarians select the most sensitive, specific, and cost-effective approach for detecting bovine mastitis early.

Brucellae as resilient intracellular pathogens: epidemiology, host-pathogen interaction, recent genomics and proteomics approaches, and future perspectives

Brucellosis is considered one of the most hazardous zoonotic diseases all over the world. It causes formidable economic losses in developed and developing countries. Despite the significant attempts to get rid of Brucella pathogens in many parts of the world, the disease continues to spread widely. Recently, many attempts proved to be effective for the prevention and control of highly contagious bovine brucellosis, which could be followed by others to achieve a prosperous future without rampant Brucella pathogens. In this study, the updated view for worldwide Brucella distribution, possible predisposing factors for emerging Brucella pathogens, immune response and different types of Brucella vaccines, genomics and proteomics approaches incorporated recently in the field of brucellosis, and future perspectives for prevention and control of bovine brucellosis have been discussed comprehensively. So, the current study will be used as a guide for researchers in planning their future work, which will pave the way for a new world without these highly contagious pathogens that have been infecting and threatening the health of humans and terrestrial animals.

Recent Advances in Fluorescent Nanoprobes for Food Safety Detection

Fluorescent nanoprobes show similar fluorescence properties to traditional organic dyes, but the addition of nanotechnology accurately controls the size, shape, chemical composition, and surface chemistry of the nanoprobes with unique characteristics and properties, such as bright luminescence, high photostability, and strong biocompatibility. For example, modifying aptamers or antibodies on a fluorescent nanoprobe provides high selectivity and specificity for different objects to be tested. Fluorescence intensity, life, and other parameters of targets can be changed by different sensing mechanisms based on the unique structural and optical characteristics of fluorescent nanoprobes. What's more, the detection of fluorescent nanoprobes is cost-saving, simple, and offers great advantages in rapid food detection. Sensing mechanisms of fluorescent nanoprobes were introduced in this paper, focusing on the application progress in pesticide residues, veterinary drug residues, heavy metals, microbes, mycotoxins, and other substances in food safety detection in recent years. A brief outlook for future development was provided as well.

Guar gum modified tilmicosin-loaded sodium alginate/gelatin composite nanogels for effective therapy of porcine proliferative enteritis caused by Lawsonia intracellularis

In order to overcome the treatment difficulty of Lawsonia intracellularis (L.intracellularis) using antibiotics, the tilmicosin (TIL)-loaded sodium alginate (SA)/gelatin composite nanogels modified with bioadhesive substances were designed. The optimized nanogels were prepared by electrostatic interaction between SA and gelatin at a mass ratio of 1:1 and CaCl₂ as an ionic crosslinker and further modified with guar gum (GG). The optimized TIL-nanogels modified with GG had a uniform spherical shape with a diameter of 18.2 ± 0.3 nm, LC of 29.4 ± 0.2 %, EE of 70.4 ± 1.6 %, PDI of 0.30 ± 0.04, and ZP of -32.2 ± 0.5 mv. The FTIR, DSC, and PXRD showed that GG was covered on the surface of TIL-nanogels in a pattern of staggered arrangements. The TIL-nanogels modified with GG had the strongest adhesive strength amongst those with I-carrageenan and locust bean gum and the plain nanogels, and thus significantly enhanced the cellular uptake and accumulation of TIL via clathrin-mediated endocytosis. It exhibited an increased therapeutic effect against L.intracellularis in vitro and in vivo. This study will provide guidance for developing nanogels for intracellular bacterial infection treatment.

Gelatin as a bioactive nanodelivery system for functional food applications

Gelatin has long been used as an encapsulant agent in the pharmaceutical and biomedical industries because of its low cost, wide availability, biocompatibility, and degradability. However, the exploitation of gelatin for nanodelivery application is not fully achieved in the functional food filed. In this review article, we highlight the latest work being performed for gelatin-based nanocarriers, including polyelectrolyte complexes, nanoemulsions, nanoliposomes, nanogels, and nanofibers. Specifically, we discuss the applications and challenges of these nanocarriers for stabilization and controlled release of bioactive compounds. To achieve better efficacy, gelatin is frequently used in combination with other biomaterials such as polysaccharides. The fabrication and synergistic effects of the newly developed gelatin composite nanocarriers are also present.

Molecular mechanism of plant elicitor daphnetin-carboxymethyl chitosan nanoparticles against Ralstonia solanacearum by activating plant system resistance

The exploration of biopolymer-based materials to avoid hazardous chemicals in agriculture has gained enormous importance for sustainable crop protection. Due to its good biocompatibility and water solubility, carboxymethyl chitosan (CMCS) has been widely applied as a pesticide carrier biomaterial. However, the mechanism by which carboxymethyl chitosan-grafted natural product nanoparticles induce tobacco systemic resistance against bacterial wilt remains largely unknown. In this study, water-soluble CMCS-grafted daphnetin (DA) nanoparticles (DA@CMCS-NPs) were successfully synthesized, characterized, and assessed for the first time. The grafting rate of DA in CMCS was 10.05 %, and the water solubility was increased. In addition, DA@CMCS-NPs significantly increased the activities of CAT, PPO and SOD defense enzymes, activated the expression of PR1 and NPR1, and suppressed the expression of JAZ3. DA@CMCS-NPs could induce immune responses against R. solanacearum in tobacco, including increases in defense enzymes and overexpression of pathogenesis-related (PR) proteins. The application of DA@CMCS-NPs effectively suppressed the development of tobacco bacterial wilt in pot experiments, and the control efficiency was as high as 74.23 %, 67.80 %, 61.67 % at 8, 10, and 12 days after inoculation. Additionally, DA@CMCS-NPs has excellent biosafety. Therefore, this study highlighted the application of DA@CMCS-NPs in manipulating tobacco to generate defense responses against R. solanacearum, which can be attributed to systemic resistance.

Intelligent-Responsive Enrofloxacin-Loaded Chitosan Oligosaccharide-Sodium Alginate Composite Core-Shell Nanogels for On-Demand Release in the Intestine

Simple Summary

Novel pharmaceutical formulations are attracting interest in their potential to overcome the poor palatability and strong gastric irritation of enrofloxacin. To overcome the difficulty of treating intestinal Escherichia coli infections, an oral intelligent-responsive chitosan-oligosaccharide (COS)–sodium alginate (SA) composite core-shell nanogel loaded with enrofloxacin was designed and systematically evaluated. Scanning electron microscopy images revealed that enrofloxacin nanogels were incorporated into the nano-sized cross-linked networks. The physical state and molecular interaction among the components of the nanogel and the enrofloxacin were evaluated by Fourier transform infrared spectroscopy. Furthermore, their biocompatible structure, high drug loading efficacy, ideal stability, “on-demand” release at the target site, and antibacterial activity were confirmed. Thus, the present study may serve as a fruitful platform to explore nanogel to resolve the challenge of enrofloxacin formulation development and the fight against intestinal bacterial infections.

Abstract

Enrofloxacin has a poor palatability and causes strong gastric irritation; the oral formulation of enrofloxacin is unavailable, which limits the treatment of Escherichia coli (E. coli) infections via oral administration. To overcome the difficulty in treating intestinal E. coli infections, an oral intelligent-responsive chitosan-oligosaccharide (COS)–sodium alginate (SA) composite core-shell nanogel loaded with enrofloxacin was explored. The formulation screening, characteristics, pH-responsive performance in gastric juice and the intestinal tract, antibacterial effects, therapeutic effects, and biosafety level of the enrofloxacin composite nanogels were investigated. The optimized concentrations of COS, SA, CaCl₂, and enrofloxacin were 8, 8, 0.2, and 5 mg/mL, respectively. The encapsulation efficiency, size, loading capacity, zeta potential, and polydispersity index of the optimized formulation were 72.4 ± 0.8%, 143.5 ± 2.6 nm, 26.6 ± 0.5%, −37.5 ± 1.5 mV, and 0.12 ± 0.07, respectively. Scanning electron microscopy images revealed that enrofloxacin-loaded nanogels were incorporated into the nano-sized cross-linked networks. Fourier transform infrared spectroscopy showed that the nanogels were prepared by the electrostatic interaction of the differently charged groups (positive amino groups (-NH₃⁺) of COS and the negative phenolic hydroxyl groups (-COO⁻) of SA). In vitro, pH-responsive release performances revealed effective pH-responsive performances, which can help facilitate targeted “on-demand” release at the target site and ensure that the enrofloxacin has an ideal stability in the stomach and a responsive release in the intestinal tract. The antibacterial activity study demonstrated that more effective bactericidal activity against E. coli could have a better treatment effect than the enrofloxacin solution. Furthermore, the enrofloxacin composite nanogels had great biocompatibility. Thus, the enrofloxacin composite core-shell nanogels might be an oral intelligent-responsive preparation to overcome the difficulty in treating intestinal bacterial infections.