Green Carbon Dots: Synthesis, Characterization, Properties and Biomedical Applications.

Carbon dots (CDs) are a new category of crystalline, quasi-spherical fluorescence, "zero-dimensional" carbon nanomaterials with a spatial size between 1 nm to 10 nm and have gained widespread attention in recent years. Green CDs are carbon dots synthesised from renewable biomass such as agro-waste, plants or medicinal plants and other organic biomaterials. Plant-mediated synthesis of CDs is a green chemistry approach that connects nanotechnology with the green synthesis of CDs. Notably, CDs made with green technology are economical and far superior to those manufactured with physicochemical methods due to their exclusive benefits, such as being affordable, having high stability, having a simple protocol, and being safer and eco-benign. Green CDs can be synthesized by using ultrasonic strategy, chemical oxidation, carbonization, solvothermal and hydrothermal processes, and microwave irradiation using various plant-based organic resources. CDs made by green technology have diverse applications in biomedical fields such as bioimaging, biosensing and nanomedicine, which are ascribed to their unique properties, including excellent luminescence effect, strong stability and good biocompatibility. This review mainly focuses on green CDs synthesis, characterization techniques, beneficial properties of plant resource-based green CDs and their biomedical applications. This review article also looks at the research gaps and future research directions for the continuous deepening of the exploration of green CDs.

Novel Polymeric Nanomaterial Based on Poly(Hydroxyethyl Methacrylate-Methacryloylamidophenylalanine) for Hypertension Treatment: Properties and Drug Release Characteristics.

In this study, a novel polymeric nanomaterial was synthesized and characterized, and it its potential usability in hypertension treatment was demonstrated. For these purposes, a poly(hydroxyethyl methacrylate-methacryloylamidophenylalanine)-based polymeric nanomaterial (p(HEMPA)) was synthesized using a mini-emulsion polymerization technique. The nanomaterials were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta size analysis. The synthesized p(HEMPA) nanomaterial had a diameter of about 113 nm. Amlodipine-binding studies were optimized by changing the reaction conditions. Under optimum conditions, amlodipine's maximum adsorption value (Qmax) of the p(HEMPA) nanopolymer was found to be 145.8 mg/g. In vitro controlled drug release rates of amlodipine, bound to the nanopolymer at the optimum conditions, were studied with the dialysis method in a simulated gastrointestinal system with pH values of 1.2, 6.8 and 7.4. It was found that 99.5% of amlodipine loaded on the nanomaterial was released at pH 7.4 and 72 h. Even after 72 h, no difference was observed in the release of AML. It can be said that the synthesized nanomaterial is suitable for oral amlodipine release. In conclusion, the synthesized nanomaterial was studied for the first time in the literature as a drug delivery system for use in the treatment of hypertension. In addition, AML-p(HEMPA) nanomaterials may enable less frequent drug uptake, have higher bioavailability, and allow for prolonged release with minimal side effects.

Synthesis and Characterization of a New Cryogel Matrix for Covalent Immobilization of Catalase.

The advantages of cryogels for enzyme immobilization applications include their mechanical and chemical robustness, ease of production, superior porosity, and low cost. Currently, many researchers are exploring porous material-based systems for enzyme immobilization that are more efficient and economically viable. Here, poly(2-Hydroxyethyl methacrylate-co-allyl glycidyl ether) (p(HEMA-co-AGE)) cryogel matrices were synthesized via the free radical cryopolymerization method to be employed as the support material. For the immobilization of the catalase enzyme onto the p(HEMA-co-AGE) cryogel matrix (catalase@p(HEMA-co-AGE), the best possible reaction conditions were determined by altering parameters such as pH, catalase initial concentration, and flow rate. The maximum catalase immobilization amount onto the p(HEMA-co-AGE) cryogel was found to be 48 mg/g cryogel. To determine the advantages of the cryogel matrix, e.g., the stability and reusability of the cryogel matrix, the adsorption-desorption cycles for the catalase enzyme were repeated five times using the same cryogel matrix. At the end of the reusability tests, it was found that the cryogel was very stable and maintained its adsorption capacity with the recovery ratio of 93.8 ± 1.2%. Therefore, the p(HEMA-co-AGE) cryogel matrix affords repeated useability, e.g., up to five times, without decreasing its catalase binding capacities significantly and has promising potential for many industrial applications. Cryogels offer clear distinctive advantages over common materials, e.g., micro/nano particles, hydrogels, films, and composites for these applications. At present, many researchers are working on the design of more effective and economically feasible, porous material-based systems for enzyme immobilization.

p(HEMA)-RR241 hydrogel membranes with micron network for IgG depletion in proteomic studies.

Serum proteins can generally be considered a good source for the illness' indication and are precious resources to detect diseases such as inflammation, cancer, diabetes, malnutrition, cardiovascular diseases, Alzheimer's, other autoimmune diseases, and infections. However, one of the biggest difficulties for proteomic studies is that the majority of serum protein mass consists of only a few proteins. Albumin and Immunoglobulin (IgG) constitute 80% of total serum protein. In this study, dye ligand affinity-based hydrogel membranes were proposed as new materials with micron mesh structures. Micron mesh p(HEMA) hydrogel membranes were synthesized by using the UV-photopolymerization method, then modified with Reactive Red 241 (RR241) dye ligand to increase the affinity towards IgG. Characterizations of synthesized micron mesh p(HEMA)-RR241 hydrogel membranes were also performed. It was demonstrated by the characterization studies that; the dye was successfully incorporated into the membrane structure with the amount of 119.38 mg/g. The hydrophilic property of the hydrogel membrane was demonstrated by swelling tests and the swelling value of dye modified membrane was found to be 8 times higher than that of the plain membrane. Micron network structure, as well as the porosity, were demonstrated with SEM/ESEM studies. Optimization of IgG adsorption conditions was also studied at different parameters (pH, temperature, ion strength, initial IgG concentration). Optimum pH, temperature, and ionic strength were found to be 6.5, 25 °C, 0.05 M, respectively, and the maximum IgG absorption value was 10.27 mg/g. Finally, it was shown that the proposed materials can be used repeatedly by 5 adsorption-desorption cycles.

Study of silanized nanostructures with immobilized fumarase for production of L-malate.

The conversion of fumaric acid into L-malate by fumarase immobilized on silanized nanostructures was analyzed experimentally. The enzyme was bound to the silanized nanostructures. We carried out scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) analysis, zeta size analysis and surface area calculation for the characterization of the nanostructures. The effect of initial enzyme concentration and pH on immobilization procedure were investigated and the change of Michaelis-Menten constants (Km and Vmax) with immobilization was examined. The change in the storage stability of the enzyme by immobilization was also investigated. The stability of the immobilized enzyme was very good. We observed that the fumarase was bound to silanized nanostructures [p(HEMA)-3-MTES] in much greater amounts. We have compared the activities of free fumarase and immobilized fumarase and we have observed a significant increase in the activity of the fumarase after immobilization for L-malate production. Moreover, we came to the conclusion that this activity can be better preserved for 30 days compared to free fumarase.

Selective nanosensor based on folic acid imprinted nanostructures.

Folic acid, which provides the transfer of single carbon atoms in synthesis reactions and metabolic cycles in metabolism, is very important for metabolism. Folic acid also plays an important role in nucleotide synthesis and methylation reactions. There are many disorders caused by defective folic acid metabolism and lack of folic acid. Today, innovative, cost-effective methods are needed to develop folic acid determination methods. The main objective of this study is the development of surface-printed carbon electrodes (SPCE) modified with folic acid imprinted nanostructures (FA-Imp-poly(MPTS-rGO-co-NAT), which will be used for the first time for folic acid determination in commercially human blood serum. For this purpose, the synthesis of nanostructures has been carried out and characterized by FTIR, SEM-EDS, and AFM. Then, a new chemically modified nanosensor was fabricated for the determination of folic acid using folic acid imprinted nanostructures. Differential pulse voltammetry (DPV) and circular voltammetry (CV) methods were used as electrochemical methods in the FA-imprinted-nanosensor studies. Measurements in differential pulse voltammetry were performed at an application speed of 0.005 volts per second in the potential range of -0.4 to 0.6 volts. As a result of the circular voltammetric method, an idea about the surface was obtained with the voltammograms obtained. The detection limit (LOD) of the developed FA-imprinted-nanosensor was 7.54 ng/mL and the determination limit (LOQ) was 25.14 ng/mL. FA analytical (10 and 20 ng/mL) was added to commercial synthetic serum samples by the standard adding method and RSD values of 0.092% and 0.734% were found in the DPV technique and measurements respectively. This manuscript demonstrated a novel, simple, selective, and rapid FA-imprinted-nanosensor for determining the FA in the biological samples.

The usage of composite nanomaterials in biomedical engineering applications.

Nanotechnology is still developing over the decades and it is commonly used in biomedical applications with the design of nanomaterials due to the several purposes. With the investigation of materials on the molecular level has increased the develop composite nanomaterials with exceptional properties using in different applications and industries. The application of these composite nanomaterials is widely used in the fields of textile, chemical, energy, defense industry, electronics, and biomedical engineering which is growing and developing on human health. Development of biosensors for the diagnosis of diseases, drug targeting and controlled release applications, medical implants and imaging techniques are the research topics of nanobiotechnology. In this review, overview of the development of nanotechnology and applications which is use of composite nanomaterials in biomedical engineering is provided.

A model study by using polymeric molecular imprinting nanomaterials for removal of penicillin G.

We aimed to develop a molecularly imprinted polymeric systems with using penicillin G as a template molecule for removal of the antibiotic residues from environmental samples. Firstly, Pen-G-imprinted poly (2-hydroxyethyl methacrylate-N-methacryloyl-L-alanine) [p(HEMA-MAAL)] nanopolymers were synthesized by surfactant-free emulsion polymerization method. Then, template molecule (Pen-G) was extracted from nanopolymers. Synthesized nanopolymers were characterized by different methods such as Fourier-transform infrared spectroscopy (FTIR), elemental and zeta-size analysis, scanning electron microscope (SEM), and surface area calculations. Nanopolymers have 60.38 nm average size and 1034.22 m2/g specific surface area. System parameters on Pen-G adsorption onto Pen-G imprint nanopolymers were investigated at different conditions. The specific adsorption value (Qmax) of molecularly impirinted p(HEMA-MAAL) nanopolymers was found 71.91 g/g for Pen-G in 5 mg/mL Pen-G initial concentration. Pen-G adsorption of molecularly imprinted nanopolymers was 15 times more than non-imprinted polymer. It is shown that obtained p(HEMA-MAAL) nanopolymer was a reuseable product which protected its adsorption capacity of 98.9% after 5th adsorption-desorption cycle. In conclusion, we suggest a method to develop a nanostructure, selective, low-cost molecularly imprinted polymeric systems with using penicillin G as a template molecule for removal of the antibiotic residues.