Nano-in-micro drug delivery system for bacterial pigment violacein

LUCIA S. CARNAGHI; RIVERO BERTI, IGNACIO; CASTRO, GUILLERMO R.; ISLAN, GERMAN A.

Buenos Aires

Workshop; Fronteras en la Nanobiotecnología III; 2022

Violacein (VIOL) is a bacterial pigment produced, among several other strains, by Chromobacterium violace-um. It has been shown that VIOL have many potential pharmacological applications, as trypanocidal, immuno-modulator, antibacterial and antitumoral drug 1. Since VIOL posses a poor solubility in water, a drug deliverysystem is required. VIOL was encapsulated into Nanostructured Lipid Carrier (NLC), following our previouswork2. Briefly, VIOL and a melted lipid phase consisting in cetyl-palmitate and capric-caprylic triglyceridesare mixed with an aqueous phase consisting of 3,0% Poloxamer P188 solution, and then sonicated in a probeultrasonic processor for 10min. VIOL in NLC encapsulation efficiency (EE, %) was higher than 99% with adrug/lipid ratio of 0.5 μmol/mg lipid and nanoparticles with a mean diameter around 200 nm (determined byDLS).To create a nano-in-micro drug delivery system (NiM), NLC-VIOL were incorporated by precipitation incalcium carbonate microparticles according to a previous paper3 with a few modifications. This could give thesystem a pH dependent behavior. Briefly 9.0ml of Na2CO3 (3.2%, w/v) were mixed with a solution containinga biopolymer, alginate (Alg), or high methoxyl pectin (HMP) from two different sources, critic pectin DM:65%HMP1 (GELFIX®), and Apple pectin DM:75% HMP2 (Sigma), and the NLC-VIOL. Then 9,0ml of glycinebuffer (pH=10.0) and 3.2% (w/v) CaCl2 were added, and the mixture stirred 5min in an ice bath, followed by10min at 1000rpm. Additionally, a preparation without biopolymer (NiM-SB) was performed. The precipitatedproduct was collected by centrifugation, washed with ultrapure water, and freeze-dried for storage. The EE(%)was measured by a direct method, extracting all VIOL in the particles with isopropanol. The EE was 17.0% forNiM-SB, 14.7% for NiM-Alg, but 49.4% or 45.4% for NiM-HMP1 and HMP2 respectively. These results in-dicate a relationship between biopolymer hydrophobicity and NLC-VIOL retention within the matrix. Opticalmicroscopy images of the NiM particles showed an average size of 2.0±0.2μm and 2.4±0.4μm for both HMPformulations, 1.2±0.5μm for NiM-SB and 2.3±0.3μm for NiM-Alg. All the formulations showed a NLC-Violcontrolled release profiles in a pH dependent behavior. NLC was effectively encapsulated in a microparticulat-ed system, forming a nano-in-micro drug delivery platform.