Iron-Reduced Graphene Oxide Core-Shell Micromotors Designed for Magnetic Guidance and Photothermal Therapy under Second Near-Infrared Light.

Core-shell micro/nanomotors have garnered significant interest in biomedicine owing to their versatile task-performing capabilities. However, their effectiveness for photothermal therapy (PTT) still faces challenges because of their poor tumor accumulation, lower light-to-heat conversion, and due to the limited penetration of near-infrared (NIR) light. In this study, we present a novel core-shell micromotor that combines magnetic and photothermal properties. It is synthesized via the template-assisted electrodeposition of iron (Fe) and reduced graphene oxide (rGO) on a microtubular pore-shaped membrane. The resulting Fe-rGO micromotor consists of a core of oval-shaped zero-valent iron nanoparticles with large magnetization. At the same time, the outer layer has a uniform reduced graphene oxide (rGO) topography. Combined, these Fe-rGO core-shell micromotors respond to magnetic forces and near-infrared (NIR) light (1064 nm), achieving a remarkable photothermal conversion efficiency of 78% at a concentration of 434 µg mL-1. They can also carry doxorubicin (DOX) and rapidly release it upon NIR irradiation. Additionally, preliminary results regarding the biocompatibility of these micromotors through in vitro tests on a 3D breast cancer model demonstrate low cytotoxicity and strong accumulation. These promising results suggest that such Fe-rGO core-shell micromotors could hold great potential for combined photothermal therapy.

Graphene-Based Nanomaterials for Photothermal Therapy in Cancer Treatment.

Graphene-based nanomaterials (GBNMs), specifically graphene oxide (GO) and reduced graphene oxide (rGO), have shown great potential in cancer therapy owing to their physicochemical properties. As GO and rGO strongly absorb light in the near-infrared (NIR) region, they are useful in photothermal therapy (PTT) for cancer treatment. However, despite the structural similarities of GO and rGO, they exhibit different influences on anticancer treatment due to their different photothermal capacities. In this review, various characterization techniques used to compare the structural features of GO and rGO are first outlined. Then, a comprehensive summary and discussion of the applicability of GBNMs in the context of PTT for diverse cancer types are presented. This discussion includes the integration of PTT with secondary therapeutic strategies, with a particular focus on the photothermal capacity achieved through near-infrared irradiation parameters and the modifications implemented. Furthermore, a dedicated section is devoted to studies on hybrid magnetic-GBNMs. Finally, the challenges and prospects associated with the utilization of GBNM in PTT, with a primary emphasis on the potential for clinical translation, are addressed.

The Influence of Size and Chemical Composition of Silver and Gold Nanoparticles on in vivo Toxicity with Potential Applications to Central Nervous System Diseases.

The physicochemical and optical properties of silver nanoparticles (SNPs) and gold nanoparticles (GNPs) have allowed them to be employed for various biomedical applications, including delivery, therapy, imaging, and as theranostic agents. However, since they are foreign body systems, they are usually redistributed and accumulated in some vital organs, which can produce toxic effects; therefore, this a crucial issue that should be considered for potential clinical trials. This review aimed to summarize the reports from the past ten years that have used SNPs and GNPs for in vivo studies on the diagnosis and treatment of brain diseases and those related to the central nervous system, emphasizing their toxicity as a crucial topic address. The article focuses on the effect of the nanoparticle´s size and chemical composition as relevant parameters for in vivo toxicity. At the beginning of this review, the general toxicity and distribution studies are discussed separately for SNPs and GNPs. Subsequently, this manuscript analyzes the principal applications of both kinds of nanoparticles for glioma, neurodegenerative, and other brain diseases, and discusses the advances in clinical trials. Finally, we analyze research prospects towards clinical applications for both types of metallic nanoparticles.

Reduced Graphene Oxides: Influence of the Reduction Method on the Electrocatalytic Effect towards Nucleic Acid Oxidation.

For the first time a critical analysis of the influence that four different graphene oxide reduction methods have on the electrochemical properties of the resulting reduced graphene oxides (RGOs) is reported. Starting from the same graphene oxide, chemical (CRGO), hydrothermal (hTRGO), electrochemical (ERGO), and thermal (TRGO) reduced graphene oxide were produced. The materials were fully characterized and the topography and electroactivity of the resulting glassy carbon modified electrodes were also evaluated. An oligonucleotide molecule was used as a model of DNA electrochemical biosensing. The results allow for the conclusion that TRGO produced the RGOs with the best electrochemical performance for oligonucleotide electroanalysis. A clear shift in the guanine oxidation peak potential to lower values (~0.100 V) and an almost two-fold increase in the current intensity were observed compared with the other RGOs. The electrocatalytic effect has a multifactorial explanation because the TRGO was the material that presented a higher polydispersity and lower sheet size, thus exposing a larger quantity of defects to the electrode surface, which produces larger physical and electrochemical areas.

Acoustically Propelled Nanomotors for Intracellular siRNA Delivery.

An effective intracellular gene silencing strategy based on acoustically propelled nanowires modified with an interfering RNA's (siRNA) payload is described. The gold nanowires (AuNW) are wrapped with a Rolling Circle Amplification (RCA) DNA strand, which serves to anchor the siRNA therapy. The ultrasound (US)-powered propulsion of the AuNW leads to fast internalization and rapid intracellular movement and hence to an accelerated siRNA delivery and silencing response. To optimize the micromotor gene silencing procedure, the influence of motion, time, and siRNA dosage was investigated, leading up to a 94% silencing after few minutes treatment with US-propelled siRNA-AuNWs, and to a dramatic (∼13-fold) improvement in the silencing response compared to the static modified nanowires. The ability of the nanomotor-based method for gene silencing has been demonstrated by measuring the GFP silencing response in two different cell lines (HEK-293 and MCF-7) and using detailed control experiments. The viability of the cells after the nanomotors treatment was examined using the MCF-7 cancer cell line. The use of DNA structures carried by the US-propelled nanomotors for gene silencing represents an efficient tool that addresses the challenges associated with RNA transportation and intracellular delivery. Future implementation of nanomachines in gene therapy applications can be expanded into a co-delivery platform for therapeutics.