Preparation and properties evaluation of Lactobacillus rhamnosus polylactic acid porous microspheres

Oral probiotics are susceptible to the gastrointestinal environment, so the number of probiotics reaching the intestine is small and difficult to colonize, limiting the application of probiotic therapy. In this study, Lactobacillus rhamnosus (LGG), a common probiotic, was chosen as a model, and layer-by-layer encapsulated LGG-loaded porous microspheres with glycol chitosan (GCS) and sodium alginate (SA) were prepared to investigate it's in vitro properties. Poly-L-lactic acid porous microspheres (PLPM) were prepared by the complex milk-solvent evaporation method, with rounded morphology, uniform size, open and connected porous structure, and the average particle size of 138.5 μm. The PLPM were co-incubated with LGG for 8 h at 37 ℃ to obtain the LGG-loaded porous microspheres (LPM) with high bacterial loadings. The surface of the LPM were wrapped with GCS and SA layer by layer by electrostatic action to obtain the layer-by-layer encapsulated LGG-loaded porous microspheres with GCS and SA (AGLPM). In vitro experiments demonstrated that AGLPM could tolerate simulated gastric fluid at pH 1.2 and simulated intestinal fluid at pH 7.4 for 2 h, and its stability was significantly better than that of bare LGG. AGLPM was a better probiotic dosage form.