Advanced functionalized nanographene oxide as a biomedical agent for drug delivery and anti-cancerous therapy: A review

Scientific Insights into the Quantum Dots (QDs)-Based Electrochemical Sensors for State-of-the-Art Applications

Size-dependent optical and electronic properties are unique characteristics of quantum dots (QDs). A significant advantage is the quantum confinement effect that allows their precise tuning to achieve required characteristics and behavior for the targeted applications. Regarding the aforementioned factors, QDs-based sensors have exhibited dramatic potential for the diverse and advanced applications. For example, QDs-based devices have been potentially utilized for bioimaging, drug delivery, cancer therapy, and environmental remediation. In recent years, use of QDs-based electrochemical sensors have been further extended in other areas like gas sensing, metal ion detection, monitoring of organic pollutants, and detection of radioactive isotopes. Objective of this study is to rationalize the QDs-based electrochemical sensors for state-of-the-art applications. This review article comprehensively illustrates the importance of aforementioned devices along with sources from which QDs devices have been formulated and fabricated. Other distinct features of QDs devices are associated with their extremely high active surfaces, inherent ability of reproducibility, sensitivity, and selectivity for the targeted analyte detection. In this review, major categories of QD materials along with justification of their key roles in electrochemical devices have been demonstrated and discussed. All categories have been evaluated with special emphasis on the advantages and drawbacks/challenges associated with QD materials. However, in the interests of readers and researchers, recent improvements also have been included and discussed. On the evaluation, it has been concluded that despite significant challenges, QDs-based electrochemical sensors exhibit excellent performances for state-of-the-art and targeted applications.

Magnetic and pH sensitive nanocomposite microspheres for controlled temozolomide delivery in glioblastoma cells

Controlled drug delivery systems have been intensively researched for cancer treatment to increase precision targeting and therapeutic efficacy. In this context, novel magnetic-/pH-sensitive graphene oxide/chitosan/iron oxide magnetic nanocomposite microspheres were synthesized. Fe3O4 (IO) nanoparticles (NPs) were synthesized via the green synthesis method in the presence of Salvia officinalis extract. The graphene oxide (GO) NPs were prepared using the Staudenmaier method, and synthesized materials were characterized. Chitosan (CS) was used to prepare microspheres. GO/CS/IO microspheres were investigated as prospective vehicles for controlled temozolomide delivery in the presence and absence of an external magnetic field. The release percentage of temozolomide molecules in the presence of 100 Hz reached a maximum in 90 min. This is approximately twice the amount of drug release in the absence of a magnetic field and more than that in the presence of a 50 Hz magnetic field. Also, the highest degree of swelling was observed at a pH of 4.5, higher than at a pH of 7.4. Also, the MTT assay results indicated the cytotoxicity of the synthesized microspheres for glioblastoma cells; notably, a significant difference was observed between the groups exposed to the magnetic field and those not, with exposure to the magnetic field further reducing survival. These results indicated that the magnetic microspheres potentially apply to controlled drug delivery systems.

UV-C driven reduction of nanographene oxide opens path for new applications in phototherapy

The main challenges associated to the application of graphene-based materials (GBM) in phototherapy are obtaining particles with lateral nanoscale dimensions and water stability that present high near-infrared (NIR) absorption. Nanosized graphene oxide (GOn) is stable in aqueous dispersion, due to the oxygen functionalities on its surface, but possesses low photothermal efficiency in NIR region. GOn total reduction originates reduced nanographene oxide (rGOn) that presents high NIR absorption, but poor water stability. In this work, we produced a partially reduced nanographene oxide (p-rGOn) by GOn photoreduction using ultraviolet radiation (UV-C), yielding nanometric particles that preserve the original water stability, but acquire high light-to-heat conversion efficiency. GOn and p-rGOn presented mean particle sizes of 170 ± 81 nm and 188 ± 99 nm, respectively. 8 h of UV-C irradiation allowed to obtain a p-rGOn stable for up 6 months in water, with a zeta potential of -32.3 ± 1.3 mV. p-rGOn water dispersions have shown to absorb NIR radiation, reaching 52.7 °C (250 µg mL-1) after 30 min NIR irradiation. Chemical characterization of p-rGOn showed a decrease in the number of characteristic oxygen functional groups, confirming GOn partial reduction. Furthermore, p-rGOn (250 µg mL-1) didn't cause any cytotoxicity (ISO10993-5:2009(E)) towards human skin fibroblasts (HFF-1) and human skin keratinocytes (HaCat), after 24 and 48 h incubation. An innovative custom-built NIR LED-system has been developed and validated for p-rGOn photothermal effect evaluation. Finally, exposure to p-rGOn+NIR-LEDs has caused no cytotoxicity towards HFF-1 or HaCat cells, revealing its potential to be used as a safe therapy.

Graphene family in cancer therapy: recent progress in cancer gene/drug delivery applications

In the past few years, the development in the construction and architecture of graphene based nanocomplexes has dramatically accelerated the use of nano-graphene for therapeutic and diagnostic purposes, fostering a new area of nano-cancer therapy. To be specific, nano-graphene is increasingly used in cancer therapy, where diagnosis and treatment are coupled to deal with the clinical difficulties and challenges of this lethal disease. As a distinct family of nanomaterials, graphene derivatives exhibit outstanding structural, mechanical, electrical, optical, and thermal capabilities. Concurrently, they can transport a wide variety of synthetic agents, including medicines and biomolecules, such as nucleic acid sequences (DNA and RNA). Herewith, we first provide an overview of the most effective functionalizing agents for graphene derivatives and afterward discuss the significant improvements in the gene and drug delivery composites based on graphene.

Polymerization and Applications of Poly(methyl methacrylate)-Graphene Oxide Nanocomposites: A Review

Graphene oxide (GO)-incorporated poly(methyl methacrylate) (PMMA) nanocomposites (PMMA-GO) have demonstrated a wide range of outstanding mechanical, electrical, and physical characteristics. It is of interest to review the synthesis of PMMA-GO nanocomposites and their applications as multifunctional structural materials. The attention of this review is to focus on the radical polymerization techniques, mainly bulk and emulsion polymerization, to prepare PMMA-GO polymeric nanocomposite materials. This review also discusses the effect of solvent polarity on the polymerization process and the types of surfactants (anionic, cationic, nonionic) and initiator used in the polymerization. PMMA-GO nanocomposite synthesis using radical polymerization-based techniques is an active topic of study with several prospects for considerable future improvement and a variety of possible emerging applications. The concentration and dispersity of GO used in the polymerization play critical roles to ensure the functionality and performance of the PMMA-GO nanocomposites.

Fabrication of r-GO/GO/α-Fe2O3/Fe2TiO5 Nanocomposite Using Natural Ilmenite and Graphite for Efficient Photocatalysis in Visible Light

Hematite (α-Fe₂O₃) and pseudobrookite (Fe₂TiO₅) suffer from poor charge transport and a high recombination effect under visible light irradiation. This study investigates the design and production of a 2D graphene-like r-GO/GO coupled α-Fe₂O₃/Fe₂TiO₅ heterojunction composite with better charge separation. It uses a simple sonochemical and hydrothermal approach followed by L-ascorbic acid chemical reduction pathway. The advantageous band offset of the α-Fe₂O₃/Fe₂TiO₅ (TF) nanocomposite between α-Fe₂O₃ and Fe₂TiO₅ forms a Type-II heterojunction at the Fe₂O₃/Fe₂TiO₅ interface, which efficiently promotes electron-hole separation. Importantly, very corrosive acid leachate resulting from the hydrochloric acid leaching of ilmenite sand, was successfully exploited to fabricate α-Fe₂O₃/Fe₂TiO₅ heterojunction. In this paper, a straightforward synthesis strategy was employed to create 2D graphene-like reduced graphene oxide (r-GO) from Ceylon graphite. The two-step process comprises oxidation of graphite to graphene oxide (GO) using the improved Hummer's method, followed by controlled reduction of GO to r-GO using L-ascorbic acid. Before the reduction of GO to the r-GO, the surface of TF heterojunction was coupled with GO and was allowed for the controlled L-ascorbic acid reduction to yield r-GO/GO/α-Fe₂O₃/Fe₂TiO₅ nanocomposite. Under visible light illumination, the photocatalytic performance of the 30% GO/TF loaded composite material greatly improved (1240 Wcm^-2). Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) examined the morphological characteristics of fabricated composites. X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), X-ray fluorescence (XRF), and diffuse reflectance spectroscopy (DRS) served to analyze the structural features of the produced composites.

Aptasensing of ciprofloxacin residue using graphene oxide modified with gold nanoparticles and branched polyethyleneimine

Precise monitoring of antibiotic residues in aqueous solution is of vital significance for safeguarding the environment and food resources. Herein, a convenient platform was fabricated for the electrochemical assay of ciprofloxacin (CFX) in real milk samples using aminated aptamer and graphene oxide nanogold-functionalized branched polyethyleneimine (GO-PEI-AuNPs) nanocomposite. For the first time, a gold electrode was modified with GO-PEI-AuNPs. The modified surface endowed excellent electrochemical substrates with large surface areas, excellent electron transfer rates, and suitable capabilities to firmly attach high amounts of aptamer. After further modification of substrate with CFX specific aptamer a recognition probe enabling selective and sensitive determination of CFX was realized. All of the aptasensor fabrication steps were surveyed via cyclic voltammetry techniques. The construction and morphology of the GO-PEI-AuNPs composite were evaluated by UV-Vis spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy. Under optimal conditions, the suggested scaffold can offer an acceptable linear range of 0.001 to 100 μM and a low limit of quantification of 0.001 μM for selective and sensitive monitoring of CFX in real samples. The effectiveness of the apta-assay was confirmed by detection of CFX in pasteurized and local milk samples for which suitable analytical results were achieved. It is expected that the developed substrate can be facilely extended to other aptamer-based multiplex screening platforms in actual food and environmental samples.

A convenient platform was fabricated for the electrochemical assay of ciprofloxacin using aminated aptamer immobilized in GO-PEI-AuNPs nanocomposite.

Nanosponges: An overlooked promising strategy to combat SARS-CoV-2

Among explored nanomaterials, nanosponge-based systems have exhibited inhibitory effects for the biological neutralization of, and antiviral delivery against, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). More studies could pave the path for clarification of their biological neutralization mechanisms as well as the assessment of their long-term biocompatibility and biosafety issues before clinical translational studies. In this review, we discuss recent advances pertaining to antiviral delivery and inhibitory effects of nanosponges against SARS-CoV-2, focusing on important challenges and opportunities. Finally, as promising approaches for recapitulating the complex structure of different organs/tissues of the body, we discuss the use of 3D in vitro models to investigate the mechanism of SARS-CoV-2 infection and to find therapeutic targets to better manage and eradicate coronavirus 2019 (COVID-19).

Design and development of biomimetic electrospun sulphonated polyether ether ketone nanofibrous scaffold for bone tissue regeneration applications: in vitro and in vivo study

Bone defect restoration remains challenging in orthopedic medical practices. In this study an attempt is carried out to probe the use of new biomimetic SPEEK (sulfonated polyether ether ketone) based nanofibrous scaffold to deliver amine functionalized hydroxyapatite nanoparticles loaded resveratrol for its potent functionality in osteogenic differentiation. SPEEK polymer with reactive functional group SO₃H was synthesized through process of sulphonation reaction. Amine functionalized nanoparticles with protonated amino groups revamp the molecular interaction by the formation of hydrogen bonds that in turn intensify the bioactivity of the nanofibrous scaffold. Osteoconductive functionalized nanohydroxyapatite enhances the cell proliferation and osteogenicity with improved cell attachment and spreading. The results of FT-IR, XRD, Carbon-Silica NMR and EDX analysis confirmed the amine functionalization of the hydroxyapatite nanoparticles. Surface morphological analysis of the fabricated nanofibers through SEM and AFM analysis shows vastly interconnected porous structure that mimics the bone extracellular matrix, which enhances the cell compatibility. Cell adhesion and live dead assay of the nanoscaffolds express less cytotoxicity. Mineralization and alkaline phosphatase assay establish the osteogenic differentiation of the nanofibrous scaffold. The in vitro biocompatibility studies reveal that the fabricated scaffold was osteo-compatible with MG63 cell lines. Hemocompatibility study further proved that the designed biomimetic nanofibrous scaffold was highly suitable for bone tissue engineering. The results of in vivo analysis in zebrafish model for the fabricated nanofibers demonstrated significant increase in the caudal fin regeneration indicating mineralization of osteoblast. Thus, the commending results obtained instigate the potentiality of the composite nanofibrous scaffold as an effective biomimetic substrate for bone tissue regeneration.