Carbon dots derived from Sanguisorbae Radix mitigate intestinal injury after severe burns: mechanisms involving barrier enhancement and oxidative stress amelioration.

BACKGROUND: As of now, effective clinical treatments for burn-induced intestinal injury are still limited. Carbon dots (CDs), recognized for their unique biological activities, present a promising avenue for the development of innovative nanomedicine-based therapies aimed at addressing intestinal barrier dysfunction following burns.

METHODS: This study reports the successful synthesis of a novel class of CDs-specifically derived from Sanguisorbae Radix carbonisata (SRC-CDs)-through a green, one-step pyrolysis method, using Sanguisorbae Radix as the sole precursor. A comprehensive suite of analytical techniques, including high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), fluorescence spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy, was employed to meticulously characterize the physicochemical properties, particle morphology, surface chemistry, and optical features of the synthesized SRC-CDs. Furthermore, the intestinal protective efficacy of SRC-CDs fabricated at varying pyrolysis temperatures (260 °C, 310 °C, 360 °C, and 410 °C) was evaluated in a murine model of 30% total body surface area (TBSA) full-thickness scald injury. Assessments included intestinal permeability biomarkers, tight junction protein expression, inflammatory cytokine levels, and oxidative stress parameters.

RESULTS: Notably, SRC-CDs synthesized across a spectrum of pyrolysis temperatures (260 °C, 310 °C, 360 °C, and 410 °C) consistently exhibited particle diameters within a defined nanoscale range (2.0-8.0 nm) and featured a rich surface chemistry characterized by diverse functional groups, irrespective of the specific thermal conditions employed. Importantly, in vivo administration of SRC-CDs conferred significant protection against burn-induced intestinal injury. This protective effect was manifested through the substantial mitigation of histopathological damage and the functional restoration of the intestinal barrier. Mechanistically, SRC-CDs treatment effectively restored intestinal barrier integrity, as demonstrated by a marked reduction in circulating levels of permeability markers, intestinal fatty acid binding protein (I-FABP) and diamine oxidase (DAO), coupled with a robust upregulation of key tight junction proteins, ZO-1 and occludin, within the intestinal mucosa. At a molecular level, SRC-CDs exerted pronounced anti-inflammatory and antioxidant actions, significantly suppressing the levels of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and the lipid peroxidation product malondialdehyde (MDA), while concurrently enhancing the activities of the endogenous antioxidant enzymes superoxide dismutase (SOD) and glutathione (GSH).

CONCLUSION: This study developed biocompatible SRC-CDs via green pyrolysis, demonstrating their efficacy in mitigating burn-induced intestinal injury. SRC-CDs enhanced barrier integrity, reduced inflammation and oxidative stress, with the 360 °C-synthesized variant showing optimal bioactivity, thereby supporting the traditional use of SR and proposing a novel nanomaterial strategy for managing critical burn complications.