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Updated: Aug 27, 2025
Evaluation of Antimicrobial Activities of Nanoparticles and Nanostructured Surfaces In Vitro
Published on: April 21, 2023
Antibacterial activity of florfenicol composite nanogels against Staphylococcus aureus small colony variants
Jinhuan Liu1, Mujie Ju1, Yifei Wu1
1Engineering Laboratory for Tarim Animal Diseases Diagnosis and Control, College of Animal Science, Tarim University, Alar, Xinjiang 843300, China.
Background:
Florfenicol might be ineffective for treating Staphylococcus aureus small colony variants (SCVs) mastitis.
Objectives:
In this study, florfenicol-loaded chitosan (CS)-sodium tripolyphosphate (TPP) composite nanogels were prepared to allow targeted delivery to SCV infected sites.
Methods:
The formulation screening, the characteristics, in vitro release, antibacterial activity, therapeutic efficacy, and biosafety of the florfenicol composite nanogels were studied.
Results:
The optimized formulation was obtained when the CS and TPP were 10 and 5 mg/mL, respectively. The encapsulation efficiency, loading capacity, size, polydispersity index, and zeta potential of the optimized florfenicol composite nanogels were 87.3% ± 2.7%, 5.8% ± 1.4%, 280.3 ± 1.5 nm, 0.15 ± 0.03, and 36.3 ± 1.4 mv, respectively. Optical and scanning electron microscopy showed that spherical particles with a relatively uniform distribution and drugs might be incorporated in cross-linked polymeric networks. The in vitro release study showed that the florfenicol composite nanogels exhibited a biphasic pattern with the sustained release of 72.2% ± 1.8% at 48 h in pH 5.5 phosphate-buffered saline. The minimal inhibitory concentrations of commercial florfenicol solution and florfenicol composite nanogels against SCVs were 1 and 0.25 µg/mL, respectively. The time-killing curves and live-dead bacterial staining showed that the florfenicol composite nanogels were concentration-dependent. Furthermore, the florfenicol composite nanogels displayed good therapeutic efficacy against SCVs mastitis. Biological safety studies showed that the florfenicol composite nanogels might be a biocompatible preparation because of their non-toxic effects on the renal tissue and liver.
Conclusions:
Florfenicol composite nanogels might improve the treatment of SCV infections.
Insights
Florfenicol composite nanogels show improved efficacy against Staphylococcus aureus small colony variants (SCVs) mastitis. This targeted delivery system enhances antibacterial activity and biosafety, offering a promising treatment for SCV infections.
Area of Science:
- Veterinary Medicine
- Nanotechnology
- Pharmacology
Background:
- Florfenicol's effectiveness is limited against Staphylococcus aureus small colony variants (SCVs) causing mastitis.
- SCVs present a therapeutic challenge due to their altered growth and metabolism.
Purpose of the Study:
- To develop and evaluate florfenicol-loaded chitosan-sodium tripolyphosphate (CS-TPP) composite nanogels.
- To enable targeted delivery of florfenicol to SCV-infected sites.
Main Methods:
- Formulation optimization of CS-TPP nanogels.
- Characterization of nanogel properties (size, zeta potential, morphology).
- In vitro release, antibacterial activity, therapeutic efficacy, and biosafety assessments.
Main Results:
- Optimized nanogels (CS 10 mg/mL, TPP 5 mg/mL) showed high encapsulation efficiency (87.3%) and sustained drug release.
- Nanogels exhibited enhanced antibacterial activity against SCVs (MIC 0.25 µg/mL vs. 1 µg/mL for commercial florfenicol).
- Demonstrated good therapeutic efficacy and biocompatibility with no observed toxicity in renal and liver tissues.
Conclusions:
- Florfenicol-loaded CS-TPP composite nanogels represent a viable strategy to improve SCV mastitis treatment.
- The nanogel formulation enhances drug delivery and efficacy while maintaining safety.
