Nanoscience & Nanotechnology-Asia - Volume 6, Issue 2, 2016

Nanoparticles offer targeted delivery of drugs, enhancing bioavailability, sustaining drug or gene effect in target tissues, and enhancing the stability. Silver nanoparticles have played a main role in the field of nanotechnology and nanomedicine. Silver nanoparticles (AgNPs) (1-100 nm in size) are produced by chemical reduction from silver nitrate using different organic compounds (Tri-ethyl-amine, Alpha-Terpineol) and organic bases (as reaction promoter). Plant extracts of Carob plant and Rumex hymenosepalu plant have also been used for the synthesis. These are made up of large amount of silver oxide due to huge ratio of surface to bulk silver atoms. Silver ions have been normally used in medicine and biology for years, but silver particles altered with nano-technological methods offers new possibilities. Silver nanoparticles account for greater than 23% of all nanoproducts and have been widely used for diagnostic and therapeutic applications (e.g. in wound healing, arthritic disease, etc.). These have been widely known for their antibacterial, antifungal, and antiviral effects. Nanosilver form has been applied in various advanced technological applications (e.g. conductive coatings). These are also employed in textile fabrics, added into cosmetic products as antiseptic as well as preservative to treat dermal problems. Thus, Silver nanoparticles (AgNPs) have been developed as a superior product in the field of nanotechnology.

Nucleotides, peptides and proteins are attracting much attention nowadays as therapeutic drugs, because of their potential in treating chronic diseases such as allergies, infectious diseases and autoimmune diseases. However, the extreme in vivo environment of human body limits the therapeutic applications of these substances. The efficacy of nucleotides can be enhanced by loading them onto nanoparticles before introducing them in the body. Nanoparticle assisted delivery may be a promising approach to alleviate the problem of instability and degradation of nucleotides. The polymeric nanoparticles have gained much attention as in vivo delivery systems due to their ability in overcoming the physiological barriers, protecting and targeting the loaded drugs to their specific location. Among various naturally occurring polymers such as cyclodextrins, emulsions, ceramics, gold shell nanoparticles; chitosan has gained more attention as drug delivery carrier. Various properties such as bactericidal, biocompatibility, low toxicity, etc make chitosan a valuable carrier and thus, it has numerous applications in the pharmaceutical field. This review summarizes some of these findings and highlights the potential of chitosan as a carrier for delivering nucleic acids.

Dimethylsulfoxide (DMSO) an organosulfur compound which is found in the environment as a result of a number of biogenic productions. It is an environmentally significant compound because of its use as a substrate by bacteria. It penetrates the skin very readily and has the unusual property that many individuals perceive a garlic-like taste in the mouth after contact of DMSO with the skin. In this paper a new analytical method using conducting polypyrrole gas sensor has been developed for the determination of DMSO at nanogram levels in water. HSO3- doped Polypyrrole sensor (PPy-HSO3) has been used for the determination of DMSO in water. The morphology of the PPy conducting film on the surface of the fibers was examined by scanning electron microscope (SEM). The PPy sensor exhibited linear responses to DMSO. The mass effects examined for DMSO indicated that the PPy-HSO3 was quite sensitive to the DMSO with good reproducibility and good detection limits. The PPy-HSO3 coupled to a capillary gas chromatograph and used for determination of DMSO in rainwater samples by using dispersive liquid–liquid microextraction (DLLME) method. Detection limit for the DMSO was 1 ng.

The existence of pharmaceutical contaminants in water has attracted increasing concern. These substances are biologically active even in small units because they retain their behaviour even after being released in the aquatic environment. Their presence in natural ecosystem is a threat to human health and other living organisms. Most of these compounds have polar structure and highly toxic in nature which are very difficult to decompose. Photocatalysis is a promising technique for the degradation of organic pollutants from aqueous phase. In this work, we have synthesized TiO2/ZnO nanocomposite using hydrothermal method and used as photocatalyst for the degradation of a pharmaceutical compound i.e. ofloxacin in aqueous phase. The synthesized nanocomposite has been characterized by various techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and BET surface area analysis. The degradation studies of ofloxacin under solar light with the prepared nanocomposite revealed promising results.

Background: In this work interaction of PPy-Ag fiber surface and some volatile organic compounds was investigated. PPy-Ag fiber sensor resistance is increased by interaction with all of organic compounds, but H2O decreases PPy-Ag fiber sensor resistance, so we can easily determine the water content of some organic compounds in nanogram levels (> 10 ng). As an innovation of this work, determination of water in organic compounds by PPy-Ag fiber sensor is done in several seconds (about 30 Sec). Furthermore, PPy-Ag sensor can determine volatile organic compounds and water concentration in a mixed solution at the same time. Methods: The PPy-Ag Nanocomposites were characterized by scanning electron microscopy (SEM) and FT-IR spectroscopy. The electrical resistance of polypyrrole-Ag fiber is strongly depended on the used doping and oxidant agents. The sensing behavior of PPy-Ag fibers in the presence of different organic solvents (in the gas phase) such as Water, Methanol, Ethanol, Acetone and so was studied experimentally. The mechanism of resistance change of sensor was investigated and the conditions that affect the determination of water were optimized. Results: Nanocomposites of polypyrrole-Ag were successfully synthesized via in situ chemical oxidation polymerization of pyrrole on the polyester fiber. Ferric chloride (FeCl3) as an oxidizing agent and silver nitrate (dopant) were used in nanocomposite polymerization. PPy-Ag gas sensor as a fast method was used to determine (30 seconds) water concentration in some organic solvents. According to the results the sensor had capability of simultaneous determination of water and solvent concentration in the gas phase. Conclusion: The resistance change of polypyrrole-Ag sensor and water concentration had a good linear relativity in the range of 4-60 ng. This technique has some advantages: low cost, good reproducibility, and sensitivity, operate simply, detect fast, safe to the environment and accurate determination of trace amounts of water in organic solvents.

Effect of humidity on the sensing properties of flexible nanocomposite thin films, such as variation of resistance with RH, hysteresis, response time and recovery time, fabricated using functionalized multiwalled carbon nanotubes (f-MWCNT) and polyvinyl alcohol (PVA) have been investigated. Scanning electron microscopy (SEM), UV-Vis spectroscopy, and X-ray diffraction (XRD) were used to characterize f-MWCNT-PVA nanocomposite thin films. The nanocomposite film with 5 wt% MWNTs loading shows promising results for humidity detection in relative humidity (RH) range of 11-94% RH. The resistance measured at 25 °C varied by more than four orders of magnitude in this RH range. This kind of nanocomposite film has many advantages since it is flexible and has good mechanical properties. Also a possible humidity-sensing mechanism of the MWCNTs/PVA composite thin film is discussed.

Eco-friendly synthesis of nanoparticles (NP) using plant extract has become very popular among nanoscience researchers. Here, we report synthesis of silver nanoparticles (AgNPs) using leaf extracts of Helianthus annuus and Mentha longifolia. These NPs were characterized by UV-Vis, TEM, XRD, Fluorescence and FTIR spectroscopy and were found to have roughly spherical morphology with average particle size of 10-25 nm in diameter. Thermal stability of the nanomaterial was estimated using TGA/DSC analysis. Antimicrobial activity of these AgNPs was also screened against Escherichia coli and the antibacterial effect was also monitored using SEM. The AgNPs were found to be better antimicrobial agent compared to standard antibiotics like ampicillin or kanamycin.

In the present study, spray-dried nanoparticles-in-microparticles system (NiMS) of Acetazolamide (ACZ) was formulated for preparing orally disintegrating tablets (ODT). The objective behind the study was to investigate the effect of - concentration of chitosan (X1), volume of sodium tripolyphosphate (NaTPP) (X2) and inlet temperature of spray dryer (X3) on entrapment efficiency of ACZ using Central Composite Design (CCD). The spray dried optimized NiMS were formulated into orally disintegrating tablets using direct compression method. It was found that batch NiMS-7 (formulated using 0.5 % w/v chitosan; 20 ml NaTPP at inlet temperature of 140ºC) has a maximum entrapment efficiency 56.08% (w/w), loading capacity 68.39% (w/w), percentage yield 30.15%, (w/w) and particle size of 455 nm. Analysis of Variance (ANOVA) was applied on the entrapment efficiency of NiMS to study the fitting and the significance of the model. The estimated model may be further utilized as response surface for entrapment efficiency of NiMS. The batch NiMS-7 showed 90.70% drug release after three hours in phosphate buffer pH 7.4 and 61.52% in 0.1 N HCl. Infrared analysis of NiMS-7 showed no interaction between drug and polymer during the formulation process. The optimized batch was further formulated into ODT. The ODT was formulated using sodium starch glycolate (52.5 mg), microcrystalline cellulose (15 mg), lactose (34.5 mg), mannitol (15 mg), talc (1.50 mg) and magnesium stearate (1.50 mg). The formulated ODTs have a disintegration time of 38 seconds. The hardness, friability and weight variation of ODTs were found to be within pharmacopoeial limits. In vitro drug release studies revealed that cumulative percent of drug released was found to be 92.90% in 60 mins and the release data followed the first order kinetics. Therefore, this NiMS approach has been successfully applied to formulate ODT of ACZ and can be advantageous for the treatment of glaucoma in the case of paediatric patients.

A 30%SrTiO3/HZSM-5 photocatalyst was synthesized by solgel method using HZSM-5 as the support for strontium titanate. The materials are mainly composed of perovskite SrTiO3 that is favored at high calcination temperature. The diffraction intensities of SrTiO3 increase with raising calcination temperature while the diffraction intensity of SrCO3 decreases at the same time. Crystal growing of the supported SrTiO3 occurs along with the increase of calcination temperature. SrTiO3 disperses on the surface of HZSM-5 after loading. Surface area of 30%SrTiO3/HZSM-5 is much larger than that of unsupported SrTiO3. The maximum photocatalytic degradation efficiency is found in the composite calcinated at 700 °C. After 90 min of irradiation, 93.8% of the initial RBR-X3B is degraded on 30%SrTiO3/0.3HZSM-5. Nearly 80% of the initial activity of the supported SrTiO3 is maintained after 4 photocatalytic recycles.