Preparation and characterization of microcapsules containing capsaicin

One-Step Encapsulation of Capsaicin into Chitosan-Oleic Acid Complex Particles: Evaluation of Encapsulation Ability and Stability

Capsaicin (CAP) demonstrates a potential for application in the food and pharmaceutical industries owing to its various attractive health benefits, including anti-cancer, anti-inflammatory, and antioxidant activities. However, the application of CAP is often limited by its low solubility in water, low bioavailability, and strong pungency. In this study, a simple one-step method for the stable encapsulation and dispersion of CAP in aqueous media was developed using polyelectrolyte complex particles formed by chitosan (CHI) and oleic acid (OA). Homogeneous particles with mean diameters below 1 μm were successfully prepared via spontaneous molecular complexation by mixing an aqueous solution of CHI with an ethanolic solution of OA and CAP. CAP was incorporated into the hydrophobic domains of the CHI-OA complex particles through hydrophobic interactions between the alkyl chains of OA and CAP. The factors affecting CAP encapsulation were investigated, and a maximum encapsulation yield of approximately 100% was obtained. The CHI-OA-CAP complex particles could be stored for more than 3 months at room temperature (22-26 °C) without resulting in macroscopic phase separation or degradation of CAP. We believe that our findings provide a useful alternative encapsulation technique for CAP and contribute to expanding its practical application.

Fabrication and Characterization of Whey Protein—Citrate Mung Bean Starch—Capsaicin Microcapsules by Spray Drying with Improved Stability and Solubility

Capsaicin was microencapsulated in six different wall systems by spray drying whey protein and citrate mung bean starch at various ratios (10:0, 9:1, 7:3, 5:5, 3:7, 1:9, 0:10) to improve its stability and water solubility and reduce its pungency. The morphological, rheological, storage stability, and physicochemical properties of capsaicin emulsion and capsaicin microcapsules were characterized. As a result, the yield of six capsaicin microcapsules was 19.63–74.99%, the encapsulation efficiency was 26.59–94.18%, the solubility was 65.97–96.32%, the moisture content was lower than 3.63% in all systems, and particle size was broadly distributed in the range of 1–60 μm. Furthermore, microcapsules with high whey protein content in the encapsulation system had an excellent emulsifier effect and wetness, smooth particle surface, and higher lightness (L*). Moreover, the system formed by composite wall materials at a ratio of whey protein to citrate mung bean starch of 7:3 had the highest retention rate and the best stability. The overall results demonstrate that whey protein combined with citrate mung starch through spray drying could be a promising strategy to produce microcapsules of poorly water-soluble compounds such as capsaicin.

Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

Carbon dots have demonstrated great potential as luminescent nanoparticles in bioapplications. Although such nanoparticles appear to exhibit low toxicity compared to other metal luminescent nanomaterials, today we know that the toxicity of carbon dots (C-dots) strongly depends on the protocol of fabrication. In this work, aqueous fluorescent C-dots have been synthesized from cinnamon, red chilli, turmeric and black pepper, by a one-pot green hydrothermal method. The synthesized C-dots were firstly characterized by means of UV-vis, fluorescence, Fourier transform infrared and Raman spectroscopy, dynamic light scattering and transmission electron microscopy. The optical performance showed an outstanding ability for imaging purposes, with quantum yields up to 43.6%. Thus, the cytotoxicity of the above mentioned spice-derived C-dots was evaluated in vitro in human glioblastoma cells (LN-229 cancer cell line) and in human kidney cells (HK-2 non-cancerous cell line). Bioimaging and viability studies were performed with different C-dot concentrations from 0.1 to 2 mg·mL^-1, exhibiting a higher uptake of C-dots in the cancer cultures compared to the non-cancerous cells. Results showed that the spice-derived C-dots inhibited cell viability dose-dependently after a 24 h incubation period, displaying a higher toxicity in LN-229, than in HK-2 cells. As a control, C-dots synthesized from citric acid did not show any significant toxicity in either cancerous or non-cancerous cells, implying that the tumour cell growth inhibition properties observed in the spice-derived C-dots can be attributed to the starting material employed for their fabrication. These results evidence that functional groups in the surface of the C-dots might be responsible for the selective cytotoxicity, as suggested by the presence of piperine in the surface of black pepper C-dots analysed by ESI-QTOF-MS.