RESUMEN
Biocompatible graphene quantum dots (GQDs), obtained from extracts of neem root, are found to be suitable for structured illumination microscopy and two-photon microscopy (TPM). Results of TPM and confocal luminescence microscopy ensure lysosome specificity in live cells and tissue-dependent localization in zebrafish, respectively, of GQDs.
Asunto(s)
Materiales Biocompatibles/química , Grafito/química , Imagen Óptica , Fotones , Puntos Cuánticos/química , Animales , Azadirachta/química , Materiales Biocompatibles/aislamiento & purificación , Grafito/aislamiento & purificación , Humanos , Lisosomas/química , Células MCF-7 , Ratones , Microscopía Confocal , Microscopía Fluorescente , Estructura Molecular , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Raíces de Plantas/química , Células RAW 264.7 , Pez CebraRESUMEN
Melatonin is a secretory product of the pineal gland that regulates circadian rhythm. It is also well-known for its anti-inflammatory and antioxidant properties against the damaging influences of reactive oxygen species. To improve its therapeutic efficacy, a new formulation with melatonin loaded in a stimuli-responsive polymeric nanocapsule has been prepared following an inverse mini-emulsion technique. The colloidal stability of the melatonin-loaded nanocapsules (MNCs) is studied using dynamic light scattering, while the morphology of these MNCs is characterized using various electron microscopies. These MNCs have an inner diameter of 80-120 nm with a cell wall thickness of 29 ± 11 nm. The emission band maximum for melatonin appears at 350 nm following excitation at 305 nm (quantum yield, Φ350 = 0.13). The self-quenching nature of the entrapped melatonin molecules inside the nanocapsules attributes to a lower Φ350 value for the MNCs. The controlled release of melatonin from MNCs in an in vitro condition is achieved by inducing a rupture of the polymeric backbone through maintaining a certain media pH (â¼2.0-4.0) as an external stimulus, and this accounts for a significant enhancement in its characteristic luminescence. The H,K-ATPase, an integral membrane protein, maintains this specific pH range in the interior of the gastrointestinal tract. This methodology is adopted for developing an efficient drug delivery process in the gastric environment. A significant improvement in the AGS cell survival under oxidative stress conditions is observed during preincubation with MNCs compared to free melatonin. In a murine model of the stress-induced gastric ulcer, MNCs outperformed free melatonin in terms of drug efficacy. The value for the gastric ulcer index is reduced from â¼30 to â¼15 by free melatonin and from â¼30 to â¼8 by MNCs treatments, respectively. Such formulation could be a step forward for developing more efficient melatonin-based gastroprotective supplements.