pH-Responsive Deacetylated Sphingan WL Gum-Based Microgels for the Oral Delivery of Ciprofloxacin Hydrochloride

Sphingan WL gum (WL) is an extracellular polysaccharide with a carboxyl group produced by <i>Sphingomonas</i> sp. WG. Recently, we have successfully obtained deacetylated WL (DWL) with good water solubility by alkaline treatment. In this study, a DWL-based microgel (named DWLM) with semi-interpenetrating network structure was constructed for the first time and used to deliver the oral drug ciprofloxacin hydrochloride (CIP). DLS results suggested that DWLM had a dual response to pH and temperature. The <i>in vitro</i> cumulative drug release curves showed that the amount of CIP released from the microgel was higher at pH 6.8 than that at pH 3.0. Biocompatibility assessments using HEK293T showed that cell viability was 75.9 ± 1.7% at the DWLM-CIP concentration of 4 mg/mL. While, the cell viability of CIP at the same concentration was only 54.9 ± 1.0%, indicating that DWLM-CIP has good biocompatibility. Antimicrobial performance tests revealed that DWLM-CIP at a concentration of 1 mg/mL could effectively inhibit the growth of <i>Escherichia coli</i> for up to 4 days. When the concentration of DWLM-CIP reached 4 mg/mL, the growth of <i>Staphylococcus aureus</i> was effectively suppressed for up to 3 days, demonstrating the long-lasting antimicrobial efficacy of DWLM-CIP. All of these results indicate that DWL-based microgels have great potential as oral drug delivery carriers.