Creation of a new proof-of-concept pectin/lysozyme nanocomplex as potential β-lactose delivery matrix: Structure and thermal stability analyses

Lactose is a disaccharide and has many uses in food and non-food formulations. Its anomeric form, beta-lactose, is a natural inhibitor of the galectin-3 protein, which is responsible for several pathological effects (e.g., colon cancer cell proliferation). However, lactose cannot be orally administered since it is rapidly hydrolyzed by intestinal lactases. Therefore, the development of nanosystems from food hydrocolloids is of particular interest as oral delivery systems for beta-lactose to enhance its chemical stability, bioaccessibility, and bioavailability. This report describes a new proof-of-concept assembling of high methoxyl pectin (HMP) and lysozyme (Ly) complexes loaded with beta-lactose produced under appropriate solution conditions (ratio, pH, and temperature) without toxic solvents. Under optimized conditions, the prepared nanoparticles had a spherical shape (81.20 +/- 0.34 nm), negative surface charge (similar to 30 mV), homogeneous size distribution (PDI <0.2), and smooth surface, as evidenced by dynamic light scattering, scanning, and transmission electron microscopes. The encapsulation efficiency of beta-lactose was greater than 96%. The particle size and morphology of the nanoparticles hardly changed with the incorporation of beta-lactose. The interaction between the compounds was evidenced by Fourier transform infrared spectroscopy and differential scanning calorimetry, indicating that intermolecular electrostatic interactions and hydrogen bonds were the driving forces to form nanoparticles and suggesting the absence of free beta-lactose on the surface of nanoparticles. Colorectal cancer cells treated with the nanocomplexes showed time-dependent incorporation of nanocomplexes. The results demonstrate a newly proof-of-concept pectin/lysozyme nanocomplexes loaded with beta-lactose, with acid galacturonans covering the nanoparticles and maintaining the thermal stability, being relevant for future application of these complexes as potential oral delivery vehicles in food matrices for low molecular weight sugars.