Ultrahigh-Efficacy VEGF Neutralization Using Carbonized Nanodonuts: Implications for Intraocular Anti-Angiogenic Therapy.

Ocular angiogenesis, associated with diseases such as retinopathy of prematurity and diabetic retinopathy, is a leading cause of irreversible vision loss. Herein, carbon nanodonuts (CNDs) with a donut-shaped structure are synthesized using sodium alginate (SA) and 1,8-diaminooctane (DAO) through a one-step thermal process. The formation of SA/DAO-CNDs occurs through a crosslinking reaction between SA and DAO, creating amide bonds followed by partial carbonization. In human retinal pigment epithelial cells exposed to H2 O2 or lipopolysaccharide, the SA/DAO-CNDs display a more than fivefold reduction in reactive oxygen species and proinflammatory cytokines, such as IL-6 and IL-1ß, when compared to carbonized nanomaterials produced exclusively from SA. Furthermore, the CNDs effectively inhibit vascular endothelial growth factor A-165 (VEGF-A165 )-induced cell migration and tube formation in human umbilical vein endothelial cells due to their strong affinity for VEGF-A165 , with a dissociation constant of 2.2 × 10-14  M, over 1600 times stronger than the commercial drug bevacizumab (Avastin). Trypsin digestion coupled with LC-MS/MS analysis reveals that VEGF-A165 interacts with SA/DAO-CNDs through its heparin-binding domain, leading to activity loss. The SA/DAO-CNDs demonstrate excellent biocompatibility and potent anti-angiogenic effects in chicken embryos and rabbit eyes. These findings suggest that SA/DAO-CNDs hold promise as a therapeutic agent for treating various angiogenesis-related ocular diseases.

In Situ Hybridization of Polymeric Curcumin to Arginine-Derived Carbon Quantum Dots for Synergistic Treatment of Bacterial Infections.

Effective infectious keratitis treatment must eliminate the pathogen, reduce the inflammatory response, and prevent persistent damage to the cornea. Infectious keratitis is generally treated with broad-spectrum antibiotics; however, they have the risk of causing corneal epithelial cell damage and drug resistance. In this study, we prepared a nanocomposite (Arg-CQDs/pCur) from arginine (Arg)-derived carbon quantum dots (Arg-CQDs) and polymeric curcumin (pCur). Partial carbonization of arginine hydrochloride in the solid state by mild pyrolysis resulted in the formation of CQDs, which exhibited enhanced antibacterial activity. pCur was formed by the polymerization of curcumin, and further crosslinking reduced its cytotoxicity and improved antioxidative, anti-inflammatory, and pro-proliferative activities. The pCur in situ conjugated with Arg-CQDs to form the Arg-CQDs/pCur nanocomposite, which showed a minimum inhibitory concentration of ca. 10 µg mL-1, which was >100-fold and >15-fold lower than that of the precursor arginine and curcumin, respectively, against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The Arg-CQDs/pCur nanocomposite with combined antibacterial, antioxidative, anti-inflammatory, pro-proliferative properties, and long-term retention on cornea enabled synergistic treatment of bacterial keratitis. In a rat model, it can effectively treat P. aeruginosa-induced bacterial keratitis at a concentration 4000-fold lower than the commercially used drug, Sulmezole eye drops. Arg-CQDs/pCur nanocomposites have great potential for application in antibacterial and anti-inflammatory nanoformulations for clinical use to treat infectious diseases.

Alleviation of dry eye syndrome with one dose of antioxidant, anti-inflammatory, and mucoadhesive lysine-carbonized nanogels.

Most dry eye syndromes (DES) are caused by oxidative stress and an overactive inflammatory response, leading to tear deficiency and excessive tear evaporation. Conventional eye drops for DES treatment require high doses and frequent administration due to their insufficient precorneal residence time. To overcome these problems, in this study, we have developed carbonized nanogels (CNGs) via the straightforward pyrolysis of lysine hydrochloride (Lys) to provide a long-lasting eye drop formulation for topical DES therapy. This methodology thermally converts Lys-into nitrogen-doped crosslinked polymers with embedded nanographitic structures, which enable efficient free radical scavenging. The cationic and crosslinked polymeric features of the Lys-CNGs also prolong the precorneal retention time and improve ocular bioavailability. These Lys-CNGs exhibit high biocompatibility with corneal epithelial cells both in vitro and in vivo, indicating their safety as eye drops. In a DES rabbit model, a single dose of Lys-CNGs (50 µg mL-1) can effectively alleviate the signs of DES within 4 days, whereas multiple treatments of 10-fold higher concentration of cyclosporine A are needed to achieve similar therapeutic effects (one dose every 12 h; 500 µg mL-1). The topical administration of Lys-CNGs enable a reduced therapeutic dose and extended dosing interval, thereby demonstrating a superior therapeutic efficacy compared to the commercial cyclosporine A eye drops. These Lys-CNGs, which exhibit significant free radical scavenging, anti-inflammatory activity, high biocompatibility, and a remarkable ocular bioadhesive property, hold great potential as a long-lasting eye drop formulation for the treatment of dry eye disease. STATEMENT OF SIGNIFICANCE: Multifunctional nanobiomaterial-based eye drops can render an ideal pharmaceutical formulation for the treatment of a variety of ocular surface diseases. To our knowledge, this is the first report describing the development of carbonized nanogels as topically administered therapeutics for alleviating dry eye syndrome (DES). We present evidence that the thermal transformation of lysine hydrochloride into carbonized nanogels (Lys-CNGs) endows superior antioxidant, anti-inflammatory, and bioadhesive properties. While a single dose of Lys-CNGs (50 µg mL-1) is sufficient to relieve the symptoms of DES for 4 days, multiple treatments of 10-fold higher concentration of commercially available cyclosporine eye drops are needed to achieve similar therapeutic outcomes (one dose every 12 h; 500 µg mL-1), suggesting an effective and long-lasting ocular carbonized nanomedicine.

Green synthesis of catalytic gold/bismuth oxyiodide nanocomposites with oxygen vacancies for treatment of bacterial infections.

We have developed a simple and green solution for the synthesis of catalytic gold-doped bismuth oxyiodide (Au/BiOI) nanocomposites at room temperature from an aqueous mixture of gold ions, bismuth ions, and iodide ions. Au nanoparticles (NPs) were formed in situ and doped into BiOI nanosheets. The oxygen vacancies generated in BiOI give rise to its oxidase-like activity, and Au doping facilitated the reaction leading to a 4-fold higher oxidase-like activity of the Au/BiOI nanocomposite. The Au/BiOI nanocomposites showed wide spectrum antimicrobial activity not only against non-multidrug-resistant E. coli, K. pneumoniae, S. enteritidis, S. aureus, and B. subtilis bacteria, but also against multidrug-resistant bacteria, methicillin-resistant S. aureus (MRSA). The gold doping reduced the minimal inhibitory concentration value by ∼2000-fold for the Au/BiOI nanocomposite, in comparison with only BiOI nanoparticles. The bactericidal property of the Au/BiOI nanocomposite arose from the combined effect of the disruption of the bacterial membrane through a strong interaction of the nanocomposite with the bacteria and the generation of reactive oxygen species. Also, the Au/BiOI nanocomposite is highly biocompatible, which has been demonstrated in vitro by analysis of cytotoxicity and hemolysis, and in vivo by evaluating ocular tissue responses. Furthermore, intrastromal administration of Au/BiOI nanocomposites can effectively alleviate S. aureus-induced bacterial keratitis in rabbits, suggesting a significant disinfectant benefit in preclinical studies. The Au/BiOI nanocomposites show great potential for the inactivation of bacterial pathogens in an aqueous environment and treatment of bacterial infection-induced diseases.

Super-Cationic Carbon Quantum Dots Synthesized from Spermidine as an Eye Drop Formulation for Topical Treatment of Bacterial Keratitis.

We have developed a one-step method to synthesize carbon quantum dots (CQDPAs) from biogenic polyamines (PAs) as an antibacterial agent for topical treatment of bacterial keratitis (BK). CQDs synthesized by direct pyrolysis of spermidine (Spd) powder through a simple dry heating treatment exhibit a solubility and yield much higher than those from putrescine and spermine. We demonstrate that CQDs obtained from Spds (CQDSpds) possess effective antibacterial activities against non-multidrug-resistant Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica serovar Enteritidis bacteria and also against the multidrug-resistant bacteria, methicillin-resistant S. aureus. The minimal inhibitory concentration (MIC) of CQDSpds is ∼2500-fold lower than that of spermidine alone, demonstrating their strong antibacterial capabilities. Investigation of the possible mechanisms behind the antibacterial activities of the as-synthesized CQDSpds indicates that the super-cationic CQDSpds with small size (diameter ca. 6 nm) and highly positive charge (ζ-potential ca. +45 mV) cause severe disruption of the bacterial membrane. In vitro cytotoxicity, hemolysis, hemagglutination, genotoxicity, and oxidative stress and in vivo morphologic and physiologic cornea change evaluations show the good biocompatibility of CQDSpds. Furthermore, topical ocular administration of CQDSpds can induce the opening of the tight junction of corneal epithelial cells, thereby leading to great antibacterial treatment of S. aureus-induced BK in rabbits. Our results suggest that CQDSpds are a promising antibacterial candidate for clinical applications in treating eye-related bacterial infections and even persistent bacteria-induced infections.

Ultrastrong trapping of VEGF by graphene oxide: Anti-angiogenesis application.

Angiogenesis is the process of formation of new blood vessels, which is essential to human biology, and also plays a crucial role in several pathologies such as tumor growth and metastasis, exudative age-related macular degeneration, and ischemia. Vascular endothelial growth factor (VEGF), in particular, VEGF-A165 is the most important pro-angiogenic factor for angiogenesis. Thus, blocking the interaction between VEGFs and their receptors is considered an effective anti-angiogenic strategy. We demonstrate for that first time that bovine serum albumin-capped graphene oxide (BSA-GO) exhibits high stability in physiological saline solution and possesses ultrastrong binding affinity towards VEGF-A165 [dissociation constant (Kd) ∼3 × 10-12 M], which is at least five orders of magnitude stronger than that of high-abundant plasma proteins such as human serum albumin, fibrinogen, transferrin, and immunoglobulin G. Due to the surprising binding specificity of BSA-GO for VEGF-A165 in complex plasma fluid, we have also studied the anti-angiogenic effects in vitro and in vivo. Results show that BSA-GO not only effectively inhibits the proliferation, migration and tube formation of human umbilical vein endothelial cells, but also strongly disturbs the physiological process of angiogenesis in chick chorioallantoic membrane and blocks VEGF-A165-induced blood vessel formation in rabbit corneal neovascularization. Our findings indicate that GO nanomaterials can potentially act as therapeutic anti-angiogenic agents via ultrastrong VEGF adsorption and its activity suppression.