Design of Fluorescent Carbon Dots (CDs) for the Selective detection of Metal-Containing Ions.

The pollution caused by heavy metals (HMs) may occur through both natural processes and anthropogenic activities and is found in complex media. The purpose of this review is to summarize the state-of-art of fluorescent CDs and the sensing applications in a systematic manner. This review intends to provide clues on the origin on the observed selectivity in chemiluminiscence sensors, which was until now a stated but unaddressed question, and still remains open for debate. Indeed, it is tempting to think that CDs possessing functional groups with soft bases at the surface are able to detect soft metal acids, while the opposite is to be suspected for hard acid-base pairs. However, the literature shows several examples where this trend does not hold. We found that such observation is explained by the involvement of dynamic quenching, which does not involve the formation of a non-fluorescent complex, as in the case of static quenching. We have provided an interpretation of published data that was not provided by the original authors and offer guidelines to enable the design of CDs to target ions in solution.

Novel Iron Oxide Nanoparticles Induce Ferroptosis in a Panel of Cancer Cell Lines.

The use of nanomaterials rationally engineered to treat cancer is a burgeoning field that has reported great medical achievements. Iron-based polymeric nano-formulations with precisely tuned physicochemical properties are an expanding and versatile therapeutic strategy for tumor treatment. Recently, a peculiar type of regulated necrosis named ferroptosis has gained increased attention as a target for cancer therapy. Here, we show for the first time that novel iron oxide nanoparticles coated with gallic acid and polyacrylic acid (IONP-GA/PAA) possess intrinsic cytotoxic activity on various cancer cell lines. Indeed, IONP-GA/PAA treatment efficiently induces ferroptosis in glioblastoma, neuroblastoma, and fibrosarcoma cells. IONP-GA/PAA-induced ferroptosis was blocked by the canonical ferroptosis inhibitors, including deferoxamine and ciclopirox olamine (iron chelators), and ferrostatin-1, the lipophilic radical trap. These ferroptosis inhibitors also prevented the lipid hydroperoxide generation promoted by the nanoparticles. Altogether, we report on novel ferroptosis-inducing iron encapsulated nanoparticles with potent anti-cancer properties, which has promising potential for further in vivo validation.

DNA-Iron Oxide Nanoparticles Conjugates: Functional Magnetic Nanoplatforms in Biomedical Applications.

The use of magnetic nanoparticles (MNPs), such as iron oxide nanoparticles (IONPs), in biomedicine is considered to be a valuable alternative to the more traditional materials due to their chemical stability, cost-effectiveness, surface functionalization, and the possibility to selectively attach and transport targeted species to the desired location under a magnetic field. One of the many main applications of MNPs is DNA separation, which enables genetic material manipulation; consequently, MNPs are used in numerous biotechnological methods, such as gene transfection and molecular recognition systems. In addition, the interaction between the surfaces of MNPs and DNA molecules and the magnetic nature of the resulting composite have facilitated the development of safe and effective gene delivery vectors to treat significant diseases, such as cancer and neurological disorders. Furthermore, the special recognition properties of nucleic acids based on the binding capacity of DNA and the magnetic behavior of the nanoparticles allowing magnetic separation and concentration of analytes have led to the development of biosensors and diagnostic assays; however, both of these applications face important challenges in terms of the improvement of selective nanocarriers and biosensing capacity. In this review, we discuss some aspects of the properties and surface functionalization of MNPs, the interactions between DNA and IONPs, the preparation of DNA nanoplatforms and their biotechnological applications, such as the magnetic separation of DNA, magnetofection, preparation of DNA vaccines, and molecular recognition tools.

Gold, Silver and Iron Oxide Nanoparticles: Synthesis and Bionanoconjugation Strategies Aimed at Electrochemical Applications.

Nanomaterials have revolutionized the sensing and biosensing fields, with the development of more sensitive and selective devices for multiple applications. Gold, silver and iron oxide nanoparticles have played a particularly major role in this development. In this review, we provide a general overview of the synthesis and characteristics of gold, silver and iron oxide nanoparticles, along with the main strategies for their surface functionalization with ligands and biomolecules. Finally, different architectures suitable for electrochemical applications are reviewed, as well as their main fabrication procedures. We conclude with some considerations from the authors' perspective regarding the promising use of these materials and the challenges to be faced in the near future.

Facile immobilization of Trametes versicolor laccase on highly monodisperse superparamagnetic iron oxide nanoparticles.

HYPOTHESIS: The development of enzymatic conjugates with industrial applications require approaches with good scalability and batch-to-batch reproducibility. Hereof, nearly monodisperse iron oxide nanoparticles can be synthesized by thermal decomposition with high yields. A mixture of gallic and polyacrylic acid is used for the direct water transfer and later immobilization of laccase (Trametes versicolor). EXPERIMENTS: Nanoparticles were synthesized by thermal decomposition (13.1 nm by TEM, 50 nm by DLS) and later transferred to water by a ligand exchange method with polyacrylic acid and a polyacrylic acid/gallic acid mixture. Laccase was immobilized on water dispersions of both nanoparticles via a carbodiimide coupling. FINDINGS: The nanoparticles exhibited superparamagnetic behavior with insignificant values of iHc. The presence of gallic acid hindered the formation of multiple polyacrylic acid layers, therefore improving the colloidal stability of the nanoparticles (100 nm by DLS) after weeks of storage. Nanoparticles containing only polyacrylic acid showed poor activity (60% loading, 4.5% activity), while nanoparticles with both polyacrylic and gallic acids showed enzymatic activity values 4.4 times higher than the free enzyme (13% loading, 57% activity). The nanoparticles improved the storage stability (8 times) of the enzyme, its thermoresistance (4 times), and its reactivity against azo dyes Camalgite and Congo Red (21 and 27% increase, respectively). In addition to some improved catalytic properties in comparison to similar works, this is the first report of the use of gallic acid for both the direct transfer to water and enzyme immobilization on highly monodisperse, batch-to-batch reproducible superparamagnetic nanoparticles.