Large variety of structure and chemical-composition of reduced graphene oxide (RGO) is explained from a quantum-chemical standpoint. The related molecular theory of graphene oxide, supported by large experience gained by the modern graphene science, has led the foundation of the concept of a multi-stage graphene oxide reduction. This microscopic approach has found a definite confirmation when analyzing the available empirical data concerning both synthetic and natural RGO products, the latter in view of shungite carbon, suggesting the atomic-microscopic model for its structure.

Monodisperse water-stable silica functionalization of upconversion nanoparticles are important for their applications in bio-imaging and bio-sensing. Here, we report on the uniform silica coating of NaYF4:Yb,Er,Tm upconversion nanoparticles (UCNPs) with a controlled thickness (3-16 nm) through a modified reverse microemulsion approach. We show that the molar ratio between tetraethylorthosilicate (TEOS) and UCNPs is important to tune the resulting thickness of silica, which can be controlled via simple increase of the concentration of UCNPs while maintaining the TEOS concentration constant. Our results show that those silica-coated upconversion nanoparticles are stable at pH = 7 sodium chloride-free solution, important for their bio-applications.

Curcumin, a useful herbal medicine with anti-inflammatory and anti-cancer properties is insoluble in water which restricts its therapeutic properties; its prominent application in cancer treatment is limited due to curcumin sub-optimal pharmacokinetics and poor bioavailability at the tumor site. Cyclodextrins have the ability to increase the solubility of many hydrophobic drugs. Several complexes have been proposed to improve the solubility of curcumin. In this study, we have demonstrated the inclusion complexation of equimolar ß-cyclodextrin and curcumin (ßCD-CUR) which is confirmed through several analytical methods such as FTIR and DSC analysis. Finally, cell viability test as well as cell morphology assessment were conducted using MTT assay on MCF7, human breast cancer cell line and L929, fibroblastic normal cells. The results showed that the inclusion complex formulation had no significant cytotoxic effect on normal cells, while there was a significant morphological changes and shrinkage in cancer cells treated by ßCD-CUR.

Chitosan (CS) as a biodegradable polymer with unique bio-attachment properties that makes it favorable to be used in biomedical applications. Insolubility in water is the problem with use of CS. The purpose of this study was to prepare low molecular weight, water-soluble CS nanoparticles that exhibit excellent water solubility and biological, chemical, and physical functions. Oxidative degradation technique using hydrogen peroxide (H2O2) was used to decrease chitosan molecular weight. Then ultrasonication and ionic gelation method using sodium tripolyphosphate (TPP) were used to prepare CS nanoparticles. Molecular weight of chitosan determined by Ubbelohde viscometry and it decreased by approximately 100%. From the spectral information (FTIR) it was observed that the cross-linking between CS and TPP was taking place while the main structure of chitosan was the same. The dynamic light scattering results showed that water-soluble nanoparticles had a multimodal size distribution pattern, while low molecular particles yielded monodisperse particle distribution with an average size of ~45 nm, which was directly ascribed to the role of ultrasonication process. The morphology of nanoparticles was observed by SEM and TEM techniques. The mean diameter of nanoparticles was obtained in a range of 30 nm to 45 nm with a narrow size distribution and polydispersity index smaller than 0.2. Cytotoxicity of CS nanoparticles on human umbilical valve endothelial cells (HUVEC) was assessed by CCK-8 assay, as well as “Live/Dead” assay and subsequent fluorescent imaging. The results showed no to minimal cytotoxicity for CS solutions up to 50 µg/ml, while sporadic dead cells observed for 100 µg/ml solutions. This suggested that our monodisperse nanoparticle systems are great candidates to be used for drug delivery systems.

According to a unique nano-confinement effect of entropic origin, predicted by us several years ago for the equilibrium state of chemical reactions, the equilibrium-constant and extent are greatly enhanced depending on the small number of molecules involved, and for many reactions also on the nano-space size. This work explored the validity of this effect in the case of elemental dimerization reactions within dilute alloy nanoparticles with separation tendency, Pd – Ir cuboctahedra in particular. Employing a simple model for the system energetics, computations based on the exact canonical partition-function reveal nano-confinement induced Ir2 dimer stabilization within Pd surface segregated nanoparticles, reflected e.g., by up to ~ 60% increased dimerization extent and by doubling of the 1n KD vs. 1/T slope, as compared to the macroscopic thermodynamic limit. The dual role of the configurational entropy, namely mixing of Ir/Ir2 vs. Pd/Ir is elucidated. Study based on more elaborate energetic models is desirable as the next step of this research.

Among the nanomaterial being applied for treatment and diagnosis field, magnetic NPs especially magnetite phase of iron oxide have been significantly interested due to their natural magnetic properties. In this study, a nanocomposition of poly (acrylic acid) and chitosan with Fe3O4 NPs were prepared in order to investigation for drug delivery systems and plasma protein adsorption. Synthesized NPs were studied by various technics including XRD, TEM, SEM, FT-IR, VSM, DLS, zeta potential and AAS. These NPs have superparamagnetic property that is essential for magnetic NPs to applying in body and drug delivery. Plasma protein adsorption is one of the most important issues for failure of nanocarriers function. In this work, BSA and IgG were used as models of proteins to study adsorption of protein onto NPs by UV-Vis spectroscopy method. Adsorption behavior of NPs for each protein was different. PAA-Fe3O4 NPs represent the lowest albumin adsorption and can be expected that have lower adsorption of protein in the body. The release profile of ascorbic acid from PAA-Fe3O4 NPs represents no sensitivity to pH, and NPs showed approximately same release behavior in pH 7.4 and 5.8.

Different polymerization techniques as particle formation processes for ciprofloxacin-loaded poly (butyl cyanoacrylate) nanoparticles (CfH-PBCN) were evaluated to choose the most appropriate in terms of the resulting nanoparticles characteristics suitable for parenteral administration. The formulations prepared by the selected technique were considered concerning size, size distribution, surface charge, loading efficiency, drug release. The mechanism of drug immobilization was also studied. Emulsion polymerization using 0.1 M HCl as an acidifying medium and Pluronic F68 as an emulsifier was found to be the best technique, leading to nanoparticles with a mean diameter below 300 nm, narrow size distribution, and a high drug payload of between 61-81 %. Analytical techniques (FTIR, GPC, XRD and 1H NMR) are consistent with a strong covalent interaction between the drug and the polymer matrix of the nanoparticles. It is proposed that CfH is involved in the initiation of the polymerization process resulting in a modification of CfH molecule that could reduce its susceptibility to efflux in Gram-positive bacteria and eukaryotic cells. The antimicrobial activity of CfH-PBCN against Bacillus subtilis 3562 and Escherichia coli K12 is similar to that of the free drug and confirms that this activity is largely unaffected by the drug’s association with the polymer nanoparticles.

In this work we describe fabrication, characterization and possible application of FITC (fluorescine isothiocyanate) conjugated magnetite nanoparticles (MNPs) for biomedical applications such as imaging of cancer cells. The MNPs possessed octahedral-like geometry with almost completely dispersed distribution with high saturation magnetization. The final FMNPs (fluorescine isothiocyanate magnetite nanoparticles) absorption band showed 30 nm red shift towards longer wavelength compared to bare MNP and the laser-induced fluorescence was observed at 518 nm. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) results showed that FITC conjugation diminishes the toxicity MNPs mainly due to the reduction of surface charge. Fluorescence microscopy confirmed the uptake and distribution of FMNPs in MCF 7 (Michigan Cancer Foundation-7) breast cancer cells, which suggests that it can be utilized for applications such as a magnetic fluorescent probe for bioassay.