Research Institute of Petroleum Industry

About: Research Institute of Petroleum Industry is a based out in . It is known for research contribution in the topics: Catalysis & Adsorption. The organization has 1370 authors who have published 2677 publications receiving 47117 citations.

Smart micro/nanoparticles in stimulus-responsive drug/gene delivery systems

Abstract: New achievements in the realm of nanoscience and innovative techniques of nanomedicine have moved micro/nanoparticles (MNPs) to the point of becoming actually useful for practical applications in the near future. Various differences between the extracellular and intracellular environments of cancerous and normal cells and the particular characteristics of tumors such as physicochemical properties, neovasculature, elasticity, surface electrical charge, and pH have motivated the design and fabrication of inventive “smart” MNPs for stimulus-responsive controlled drug release. These novel MNPs can be tailored to be responsive to pH variations, redox potential, enzymatic activation, thermal gradients, magnetic fields, light, and ultrasound (US), or can even be responsive to dual or multi-combinations of different stimuli. This unparalleled capability has increased their importance as site-specific controlled drug delivery systems (DDSs) and has encouraged their rapid development in recent years. An in-depth understanding of the underlying mechanisms of these DDS approaches is expected to further contribute to this groundbreaking field of nanomedicine. Smart nanocarriers in the form of MNPs that can be triggered by internal or external stimulus are summarized and discussed in the present review, including pH-sensitive peptides and polymers, redox-responsive micelles and nanogels, thermo- or magnetic-responsive nanoparticles (NPs), mechanical- or electrical-responsive MNPs, light or ultrasound-sensitive particles, and multi-responsive MNPs including dual stimuli-sensitive nanosheets of graphene. This review highlights the recent advances of smart MNPs categorized according to their activation stimulus (physical, chemical, or biological) and looks forward to future pharmaceutical applications.

The effect of Si/Al ratio of ZSM-5 zeolite on its morphology, acidity and crystal size

Abstract: ZSM-5 zeolite crystal with different Si/Al molar ratios in the range of 10-50 was synthesized using sodium silicate, aluminum sulfate and tetrapropylammonium bromide (TPA-Br) as the organic template. The produced samples were characterized using XRD, FT-IR, SEM and EDX techniques. All synthesized samples were found to be ZSM-5 zeolite as confirmed by XRD and supported by FT-IR. SEM results showed that ZSM-5 synthesized with different Si/Al molar ratios had different morphologies and particle sizes. It was found that the average ZSM-5 crystal size increased as Si/Al molar ratio increased. Thermogravimetric-difference thermal analysis (TG-DTA) technique was also used to measure the amount of template occluded inside the crystal pore. The synthesized Na-ZSM-5 was transformed into its acidic form, i.e., H-ZSM-5 using ion exchange method with ammonium nitrate solution. The H-ZSM-5 acidity was determined by NH3-TPD. These results showed that different Si/Al molar ratios have effect on surface acidity of samples. The surface areas of the H-ZSM-5 were measured using BET method and the results showed that, decrease in Si/Al ratio, decreased the surface area. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)