Intratumor delivery of amino-modified graphene oxide as a multifunctional photothermal agent for efficient antitumor phototherapy.

Due to the high selectivity and non-invasive property, phototherapy has attracted increasing attention in the treatment of cancer. Targeted delivery and retention of photoactive agents in tumor tissue is of great significance and importance for safe and efficient phototherapy. Herein, we report a multifunctional nanomaterial photothermal agent, namely amino-modified graphene oxide (AGO) for anti-oral cancer photothermal therapy (PTT). Compared to the parental graphene oxide (GO) which has a negative charge and weak photothermal effect, AGO possesses a positive charge (∼+50 mV) and the significantly enhanced photothermal effect. Positive charge allows AGO to efficiently interact with tumor cells and retain in tumor tissue after intratumor injection. The enhanced photothermal effect allows AGO to achieve the tunable and efficient PTT. In vitro results show that AGO (15 µg/mL) reduces the viability of HSC-3 cells (oral squamous cell carcinoma cell line) to 5% under near infrared (NIR) irradiation (temperature increased to 58.4 °C). In vivo antitumor study shows that intratumor delivery of AGO (200 µg/mouse) has no inhibition effects on tumor growth (454% of initial tumor size) without NIR. With a single dose of NIR irradiation, however, AGO significantly reduces the tumor size to 25% of initial size in 1 of 4 mice, and even induces the complete tumor ablation in 3 of 4 mice. Furthermore, the injected AGO falls off along with the scab after PTT. Our findings indicate that AGO is a potential nano-photothermal agent for tunable, convenient and efficient anticancer PTT.

Nanomaterials-based photosensitizers and delivery systems for photodynamic cancer therapy.

The increasing cancer morbidity and mortality requires the development of high-efficiency and low-toxicity anticancer approaches. In recent years, photodynamic therapy (PDT) has attracted much attention in cancer therapy due to its non-invasive features and low side effects. Photosensitizer (PS) is one of the key factors of PDT, and its successful delivery largely determines the outcome of PDT. Although a few PS molecules have been approved for clinical use, PDT is still limited by the low stability and poor tumor targeting capacity of PSs. Various nanomaterial systems have shown great potentials in improving PDT, such as metal nanoparticles, graphene-based nanomaterials, liposomes, ROS-sensitive nanocarriers and supramolecular nanomaterials. The small molecular PSs can be loaded in functional nanomaterials to enhance the PS stability and tumor targeted delivery, and some functionalized nanomaterials themselves can be directly used as PSs. Herein, we aim to provide a comprehensive understanding of PDT, and summarize the recent progress of nanomaterials-based PSs and delivery systems in anticancer PDT. In addition, the concerns of nanomaterials-based PDT including low tumor targeting capacity, limited light penetration, hypoxia and nonspecific protein corona formation are discussed. The possible solutions to these concerns are also discussed.

Ti3C2Tx MXene loaded with indocyanine green for synergistic photothermal and photodynamic therapy for drug-resistant bacterium.

Infections caused by antibiotic-resistant bacteria are a critical threat to human health. Considering the difficulties and time-consuming nature of synthesizing new antibiotics, it is of great significance and importance to develop the antibiotic-independent antibacterial approaches against drug-resistant bacteria. Nanomaterials-based photothermal therapy (PTT) and photodynamic therapy (PDT) have attracted much attention due to their broad-spectrum bactericidal activity, low toxicity, and drug-free feature. In this work, we loaded indocyanine green (ICG) on the Ti3C2Tx MXene nanosheets (454 nm) so as to combine the photothermal effect of MXene with the photodynamic effect of ICG. Without near-infrared (NIR) irradiation, MXene (20 µg/mL), ICG (5 µg/mL) or ICG-loaded MXene (ICG-MXene) showed no significant antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Under NIR, however, the viability loss of MRSA remarkably increased to 45% for MXene, 66% for ICG and 100% for ICG-MXene. We further found that the great anti-MRSA activity of ICG-MXene under NIR was attributed to the combination of photothermal effect of MXene (high temperature) and photodynamic effect of ICG (high level of reactive oxygen species). Our findings indicate that MXene can be used as both the photothermal agent and the carrier of photosensitizers to achieve the synergistic PTT/PDT therapy for bacterial infections.

Graphene Oxide Nanosheets with Efficient Antibacterial Activity Against Methicillin-Resistant Staphylococcus aureus (MRSA).

The development of drug-resistant bacteria has become a public health problem, among which methicillin-resistant Staphylococcus aureus (MRSA) leads to various life-threatening diseases. Graphene oxide (GO) is a two-dimensional nanomaterial with potential in the anti-MRSA treatment. This study prepared GO nanosheets with fixed lamellar size, investigated its antibacterial activity against MRSA, and analyzed the related antibacterial mechanisms. We found that the fabrication of GO with stable dispersion was workable. Furthermore, such GO had superior antibacterial performance against MRSA at low concentrations with the dose-dependent anti-MRSA effect. The GO-MRSA interaction also provided fundamental support for the antibacterial mechanisms with cleavage and encapsulation effects. In conclusion, GO nanosheets may be a promising antimicrobial agent against MRSA.