In this study, two green procedures for Silver-Graphene Oxide (Ag-GO) nanocomposite synthesis were investigated. As a common method, AgNO
3
was first loaded on the GO surface and then was reduced and stabilized by walnut green husk extract, producing Ag-GO-І. As an innovative approach, GO was first exposed to the extract and then the AgNO
3
was added as the second step, producing Ag-GO-П. Physicochemical properties, antibacterial and cytotoxicity activity of both nanocomposites were subsequently studied comparing with free silver nanoparticles (AgNPs) and pure GO. Based on the results, exposure of GO to the extract, as a reducing agent, at the first/last step of the synthesis process resulted in the fundamental differences in the final products. So that, high amounts of agglomerated silver nanoparticles were formed between the GO sheets, when using the common method, whereas in Ag-GO-П, small AgNPs were formed on the GO sheets without aggregation, entirely covering the sheets. Antibacterial and cytotoxic behavior of these nanomaterials could be compared as AgNPs > Ag-GO-П > Ag-GO-І. It is assumed that these differences are due to control of unwanted nucleation in the synthesis process that Ag nanoparticles are smaller with less agglomeration when the GO surfaces are pre-treated with reducing agent.
Organoids are powerful systems to facilitate the study of individuals' disorders and personalized treatments. This emerging technology has improved the chance of translatability of drugs for preclinical therapies and mimicking of the complexity of organs, proposing numerous approaches for human disease modeling, tissue engineering, drug development, diagnosis, and regenerative medicine. In this review, we outline the history of organoid technology and summarize its faithful applications, and then we discuss the challenges and limitations encountered by three-dimensional organoids. Finally, we propose that human organoids offer a basic mechanistic infrastructure for “human modeling” systems to prescribe personalized medicines.
Human respiratory viral infections are the leading cause of morbidity and mortality
around the world. Among the various respiratory viruses, coronaviruses (e.g.,
SARS-CoV-2) have created the greatest challenge and most frightening health threat
worldwide. Human coronaviruses typically infect the upper respiratory tract, causing
illnesses that range from common cold-like symptoms to severe acute respiratory
infections. Several promising vaccine formulations have become available since the
beginning of 2021. Nevertheless, achievement of herd immunity is still far from being
realized. Social distancing remains the only effective measure against SARS-CoV-2
infection. Nanobiotechnology enables the design of nanobiosensors. These nanomedical
diagnostic devices have opened new vistas for early detection of viral infections. The
present review outlines recent research on the effectiveness of nanoplatforms as
diagnostic and antiviral tools against coronaviruses. The biological properties of
coronavirus and infected host organs are discussed. The challenges and limitations
encountered in combating SARS-CoV-2 are highlighted. Potential nanodevices such as
nanosensors, nanobased vaccines, and smart nanomedicines are subsequently presented for
combating current and future mutated versions of coronaviruses.
Intrinsic fluorescence and versatile optical properties of Graphene Oxide (GO) in visible and near-infrared range introduce this nanomaterial as a promising candidate for numerous clinical applications for early-diagnose of diseases. Despite recent progresses in the impact of major features of GO on the photoluminescence properties of GO, their modifications have not yet systematically understood. Here, to study the modification effects on the fluorescence behavior, poly ethylene glycol (PEG) polymer, metal nanoparticles (Au and Fe3O4) and folic acid (FA) molecules were used to functionalize the GO surface. The fluorescence performances in different environments (water, DMEM cell media and phosphate buffer with two different pH values) were assessed through fluorescence spectroscopy and fluorescent microscopy, while Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were utilized to evaluate the modifications of chemical structures. The modification of GO with desired molecules improved the photoluminescence property. The synthesized platforms of GO-PEG, GO-PEG-Au, GO-PEG-Fe3O4 and GO-PEG-FA illustrated emissions in three main fluorescence regions (blue, green and red), suitable for tracing and bio-imaging purposes. Considering MTT results, these platforms potentially positioned themselves as non-invasive optical sensors for the diagnosis alternatives of traditional imaging agents.
An effective strategy to inhibit endocytosis in cancer cells is presented where modified net-type graphene oxide (GO) sheets, bound with multiple cell surface receptors, are introduced and synthesized as novel anticancer agents. The results suggest that the binding connects GO sheets with neighboring lipid rafts, neutralizes endocytosis, and causes metabolic deprivation. As a result, tumor cell survival and proliferation are reduced. Live cell confocal microscopy imaging reveals that GO-PEGFA (folate-PEGylated GO) (PEG, polyethylene glycol) is internalized by tumor cells, while GO-PEGRGD (tripeptide Arg-Gly-Asp PEGylated GO) associates with the external cell membrane (not internalized). In vitro exposure of tumor cells to GO-PEGFA or GO-PEGRGD reduces the cell viability by 35%, compared to 50% reduction using methotrexate (100 μM). The combination of modified GO sheets with methotrexate or doxorubicin shows a greater toxicity (80% reduction in cell viability) than the individual agents. The proposed setup demonstrates a significant synergy in limiting tumor cell growth.
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