Photochemical synthesis, characterization, and electrochemical sensing properties of CD-AuNP nanohybrids

Among the existing nanosystems used in electrochemical sensing, gold nanoparticles (AuNPs) have attracted considerable attention owing to their intriguing chemical and physical properties such as good electrical conductivity, high electrocatalytic activity, and high surface-to-volume ratio. However, despite these useful characteristics, there are some issues due to their instability in solution that can give rise to aggregation phenomena and the use of hazardous chemicals in the most common synthetic procedures. With an aim to find a solution to these issues, recently, we prepared and characterized carbon dots (CDs), from olive solid wastes, and employed them as reducing and capping agents in photo-activated AuNP synthesis, thus creating CD-Au nanohybrids. These nanomaterials appear extremely stable in aqueous solutions at room temperature, are contemporary, and have been obtained using CDs, which are exclusively based on non-toxic elements, with an additional advantage of being generated from an otherwise waste material. In this paper, the synthesis and characterization of CD-Au nanohybrids are described, and the electrochemical experiments for hydroquinone detection are discussed. The results indicate that CD-Au acts as an efficient material for sensing hydroquinone, matching a wide range of interests in science from industrial processes to environmental pollution.

Carbon Dots: An Innovative Tool for Drug Delivery in Brain Tumors

Brain tumors are particularly aggressive and represent a significant cause of morbidity and mortality in adults and children, affecting the global population and being responsible for 2.6% of all cancer deaths (as well as 30% of those in children and 20% in young adults). The blood-brain barrier (BBB) excludes almost 100% of the drugs targeting brain neoplasms, representing one of the most significant challenges to current brain cancer therapy. In the last decades, carbon dots have increasingly played the role of drug delivery systems with theranostic applications against cancer, thanks to their bright photoluminescence, solubility in bodily fluids, chemical stability, and biocompatibility. After a summary outlining brain tumors and the current drug delivery strategies devised in their therapeutic management, this review explores the most recent literature about the advances and open challenges in the employment of carbon dots as both diagnostic and therapeutic agents in the treatment of brain cancers, together with the strategies devised to allow them to cross the BBB effectively.

Carbon Dots as Promising Tools for Cancer Diagnosis and Therapy

Simple Summary

Diagnostic approaches and chemotherapeutic delivery based on nanotechnologies, such as nanoparticles (NPs), could be promising candidates for the new era of cancer research. Recently great attention has been received by carbon-based nanomaterials such as Carbon Dots (CDs), due their variegated physical-chemical properties that makes these systems appealing for multiple use from bioimaging, biosensing, nano-carriers for drug delivery systems to innovative therapeutic agents in photodynamic (PDT) and photothermal therapy (PTT). In this review, we report the last evidence on the application and prospects of CDs as useful nano theranostics tools for cancer diagnosis and therapy.

Abstract

Carbon Dots (CDs) are the latest members of carbon-based nanomaterials, which since their discovery have attracted notable attention due to their chemical and mechanical properties, brilliant fluorescence, high photostability, and good biocompatibility. Together with the ease and affordable preparation costs, these intrinsic features make CDs the most promising nanomaterials for multiple applications in the biological field, such as bioimaging, biotherapy, and gene/drug delivery. This review will illustrate the most recent applications of CDs in the biomedical field, focusing on their biocompatibility, fluorescence, low cytotoxicity, cellular uptake, and theranostic properties to highlight above all their usefulness as a promising tool for cancer diagnosis and therapy.

A new Ag-nanostructured hydroxyapatite porous scaffold: Antibacterial effect and cytotoxicity study

We report a new chemical method for the functionalization of Mg-hydroxyapatite (Mg-HA) scaffold with Ag nanoparticles (Ag NPs) integrating in one step both the synthesis of the Ag NPs and their nano-structuring into the HA matrix (Ag-Mg-HA scaffold). This method exploits a green photochemical synthesis and allows the direct growth of Ag NPs on the Mg-HA surface. The surface structure of Ag-Mg-HA scaffold, investigated by scanning electron microscopy, shows no significant changes in the morphology upon Ag NPs incorporation. The presence of Ag was confirmed by EDX analysis. TEM and spectroscopic investigations show Ag NPs spherical shaped with a mean diameter of about 20 nm exhibiting the typical plasmon absorption band with maximum at 420 nm. The antibacterial properties of Ag-Mg-HA scaffolds were tested against two bacterial strains, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results show excellent antibacterial properties achieving up to 99% and 100% reduction of colonies for both bacteria cultures after 24 h of incubation and 100% of reduction after 48 h of incubation. The cytotoxicity of Ag-Mg-HA was also in deep investigated assessing both cell proliferation and differentiation using hADSCs (human Adipose Derived Stem Cells) and testing data point at 0, 7, 14 and 24 days. The results show cytotoxic effect with cell proliferation decreasing up to 90% at 24 days and osteogenic differentiation inhibition. The observed cytotoxicity can be probable ascribed to the oxidative stress by ROS. Indeed, considering the effectiveness of the nanofunctionalization method and the excellent antibacterial properties showed by the Ag-Mg-HA scaffold, future works will be devoted to create nanofunctionalized scaffold satisfying both antimicrobial and osteo-regenerative properties.