Carbon-in-carbon: Hybrid carbonized nanomaterials with multifunctional activities for the treatment of endophthalmitis

Infectious endophthalmitis (EO) is a severe eye condition characterized by inflammation of the eye's internal fluids and tissues, often resulting from infection by bacteria or fungi. Patients with EO typically experience reduced vision, pain, and conjunctival infection. Despite the use of antibiotics, challenges such as inflammation and drug resistance remain. In this work, we have developed dextran/aliphatic diamines carbonized nanogels (DEX/ADA-CNGs) as board-spectrum antimicrobial agents by a one-step mild carbonization procedure. The CNGs exhibit not only antimicrobial properties but also show good drug delivery potential. Curcumin-based carbon quantum dots (Cur-CQDs) as an anti-inflammatory agent are loaded into DEX/ADA-CNGs to form hybrid carbon-in-carbon nanocomposites (Cur-CQDs@DEX/ADA-CNGs), showing combined antimicrobial, antioxidative, and anti-inflammatory activities. Impressively, CQDs@DEX/ADA-CNGs maintain strong antibacterial effectiveness against drug-resistant strains, with minimum inhibitory concentrations below 110 µg mL⁻¹. The Cur-CQDs@DEX/ADA-CNGs have demonstrated high biocompatibility both in vitro and in vivo. In a rat model of EO, they rapidly (less than 5 days) reduce microbial infection and inflammation in the eye. Given these promising results, Cur-CQDs@DEX/ADA-CNGs show great potential as an enduring intravitreal treatment option for infectious EO.