Monodisperse Gold Nanoparticles: A Review on Synthesis and Their Application in Modern Medicine

Gold nanoparticles (AuNPs) are becoming increasingly popular as drug carriers due to their unique properties such as size tenability, multivalency, low toxicity and biocompatibility. AuNPs have physical features that distinguish them from bulk materials, small molecules and other nanoscale particles. Their unique combination of characteristics is just now being fully realized in various biomedical applications. In this review, we focus on the research accomplishments and new opportunities in this field, and we describe the rising developments in the use of monodisperse AuNPs for diagnostic and therapeutic applications. This study addresses the key principles and the most recent published data, focusing on monodisperse AuNP synthesis, surface modifications, and future theranostic applications. Moving forward, we also consider the possible development of functionalized monodisperse AuNPs for theranostic applications based on these efforts. We anticipate that as research advances, flexible AuNPs will become a crucial platform for medical applications.     

Analysis and Optimization of Ultrasound-Assisted Alkaline Palm Oil Transesterification by RSM and ANN-GA

In this study, the effects of ultrasound irradiation on transesterification process and characteristics of the synthesized biodiesel were investigated. The study was divided into two parts. In the first part, response surface methodology (RSM) and Central Composite Design (CCD) were employed to design experiments, develop the regression model, and evaluate individual and interactive impacts of five independent operational variables. The obtained results were then predicted by an optimized artificial neural network-genetic algorithm (ANN-GA) algorithm. The estimated results were compared with the experimental results. In the second part of the work, the impact of ultrasound irradiation on the main characteristics of the synthesized biodiesel was investigated. The analysis of the operating conditions indicated that reaction temperature and MeOH:oil molar ratio were the most important variables on reaction yield. The experimental results showed that there was a change in the main properties of the synthesized palm oil biodiesel with the density changed by about 0.3 kg/m³, viscosity by 0.12 mm²/s, pour/cloud point by 1–2°C, and flash point by 5°C, depending on different combinations of operational parameters. Besides, the numerical optimization technique was employed to optimize process variables in order to obtain the maximum FAME content (reaction yield) along with the best properties using both RSM and ANN-GA techniques. The maximum reaction yields of 95.2% and 95.1% were predicted by the RSM and ANN-GA models, respectively, at the optimum conditions. The conditions predicted by RSM and ANN-GA proved to be feasible for modeling and optimizing transesterfication yield with an accuracy of 99.18% and 99.14% and biodiesel properties of 98.61% and 98.28%, respectively.     

Stability of nanoparticles during semibatch emulsion polymerization of butyl methacrylate,in the presence of methacrylic acid via RSM

The size and stability of latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of 0–10% methacrylic acid (MAA), were investigated. Response surface methodology (RSM), as a design of experiment, was used to obtain a more systematic understanding of the role of emulsifier and MAA in the stability of the particles. The amount of coagulum can be greatly reduced by increasing the concentration of sodium lauryl sulfate (SLS) in the monomer emulsion feed (MEF) and initial reactor charge (IRC). On the other hand, increasing the concentration of SLS in the IRC can result in a decrease of the particles size. According to the experimental data, the yield of reaction can be improved with incorporation of MAA into the emulsion polymers. The size and morphology of particles were obtained by scanning electron microscopy (SEM). FTIR and titration were used to determine the percentage of MAA in the copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Experimental investigation and CFD simulation of turbulence effect on hydrodynamic and mass transfer in a packed bed airlift internal loop reactor

The experimental investigation and its simulation using computational fluid dynamics (CFD) of hydrodynamic and mass transfer for two phase bubbly flow in a split cylindrical airlift reactor were carried out. The turbulence influences on mass transfer and hydrodynamic parameters were considered when packing was installed in the riser zone. Further, CFD was properly able to simulate hydrodynamic and mass transfer in a bubbly flow. Packing existence in an airlift reactor increased gas hold-up and decreased liquid velocity. The lower velocity increased the delay time (residence time), which increased the mass transfer. Since there is random and erratic movement of liquid bulk layers and dynamic fluctuations in a packed bed airlift reactor so, Reynolds number increased and resulted in mass and momentum transfer enhancement. In an unpacked reactor, the superficial gas velocity enhancement changed the flow regime from homogenous to transition while in packed bed reactor the homogenous flow regime was only observed.     

Mass Transfer Study of Newtonian Fluids with Different Viscosity under Low-Frequency,High-Power Ultrasound Irradiation

In this article, the effects of liquid properties and operating conditions on gas–liquid mass transfer under ultrasound irradiation and mechanical stirring were studied and compared. Response surface methodology (RSM) was utilized for the design of experiments and evaluation of the influence of operating parameters. The maximum value of volumetric mass transfer coefficient (k_La) was found to be 0.0714?s^?1 when the ultrasonic horn was located horizontally just above the gas sparger in the tank. Ultrasonic power and the position of ultrasonic horn were found to be the most significant parameters that influence k_La. Also, three empirical correlations were developed to estimate k_La considering liquid viscosity as one of the main parameters, and their estimations were compared to those estimated using existing correlations in the literature.     

Sensitive molecular determination of polycyclic aromatic hydrocarbons based on thiolated Calix[4]arene and CdSe quantum dots (QDs)

A novel and sensitive electrochemical sensor based on the cone conformation of the supramolecule 25, 27-(3-thiopropoxy)-p-tert-butyl calix[4]arene has been developed for quantitative determination of polycyclic aromatic hydrocarbons (PAHs). The method works effectively by immobilizing calix[4]arenes on Fe₃O₄ magnetic nanoparticles. CdSe quantum dots were used as electrochemical labels. CdSe quantum dots (QDs) modified PAHs in competition with the sample PAHs were intercalated into calix[4]arenes supramolecules via a host–guest interaction through individual bowl-shaped calix[4]arenes. The stripping analysis of the cadmium dissolved from CdSe nanoparticles provided a sensitive method for the detection of PAHs in the samples. The signal decrease of the QDs was proportional to the increase in the concentration of the PAHs. Under optimal conditions, among the five PAHs, the square wave voltammetry (SWV) response of QDs decreased linearly for anthracene and naphthalene in the range of 2.1 × 10^?7–1.4 × 10^?5 and 1.5 × 10^?6–2.5 × 10^?5 M, respectively. The calculated detection limits (3δ) were 20.1 ng mL^?1 for anthracene and 105.5 ng mL^?1 for naphthalene.     

Degradation of 4-nitrophenol (4-NP) using ZnO nanoparticles supported on zeolites and modeling of experimental results by artificial neural networks

In this paper, we report the synthesis of ZnO, ZnO/HZSM-5, ZnO/HY and ZnO/Clin by a poly acrylamide pyrolysis method for the first time. The presences of carbon network/cages in the poly acrylamide gel can effectively prevent particle agglomeration. The catalytic activity of all specimens was tested by carrying out the 4-nitrophenol degradation, used as a “probe” reaction, in the aqueous medium under ambient visible light. The prepared samples were characterized by X-ray diffraction (XRD), specific surface area (BET) and porosity determination, scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), visible-ultraviolet diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR), to evaluate particle structure, size distribution and composition. The results revealed that among the catalysts, ZnO/HZSM-5 showed higher percentage of adsorption than others. The time required for complete mineralization of 4-NP under ambient visible light over ZnO/HZSM-5 was 75 min. The higher activity of ZnO/HZSM-5 is mainly due to fine dispersion of ZnO and hydrophobicity of the support. An artificial neural networks (ANNs) model was developed to predict the performance of catalytic degradation process over synthesized catalysts based on experimental data. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.