Preparation and characterization of dopamine-loaded bacterial cargo for anti-inflammatory applications

Inflammation in the gastrointestinal tract is developing predominantly because of autoimmune responses and microbiome imbalance. Owing to the reoccurrence of behavior, the treatment is highly complicated and ineffective. Hence, this study aimed to prepare a gastrointestinal drug delivery system targeting intestinal inflammation based on heat-killed Lactobacillus rhamnosus (LR-T) to deliver the neuronal transmitter dopamine for effective treatment. The heat-killing process did not influence the intact structure of LR but decreased their length significantly. Besides, the surface functional properties of live LR (LR-C) were similar to LR-T determined in FTIR. However, the surface charge was more negative in LR-T (−25.26 ± 0.41 mV) compared to LR-C (−10.33 ± 0.32 mV). Further, the loading of DA (−17.06 ± 4.39 mV) increased the zeta potential of LR-T (−39.93 ± 1.25 mV). Besides, LR-T exhibits a higher loading (14.57 ± 0.89 %) and encapsulation (59.46 ± 0.8 %) efficiency of DA with an optimum ratio of 1:0.3. The release pattern of DA depends on the time and pH. The cytotoxic analysis confirmed that LR-T has significantly attenuated the toxicity of higher concentration DA. Furthermore, this study confirmed that LR-T decreased cell toxicity (cell death and mitochondrial membrane potential loss) compared to LR-C. In addition, LR-T-DA induced higher cell proliferation in NIH3T3 cells. Hence, this preliminary investigation confirmed that heat-killed or inactivated LR could be used for inexpensive oral delivery of therapeutics.