Tunable Surface Plasmon Resonance-Based Remote Actuation of Bimetallic Core-Shell Nanoparticle-Coated Stimuli Responsive Polymer for Switchable Chemo-Photothermal Synergistic Cancer Therapy.

New dual light/temperature-responsive nanocarriers were synthesized using bimetallic plasmonic Au-Ag and Ag-Au nanoparticles (NPs) as cores of vehicles which subsequently functionalized with an upper critical solubility temperature-based poly acrylamide-co-acrylonitrile using reversible addition-fragmentation chain transfer for spatiotemporally controlled chemo-photothermal synergistic cancer therapy. The bimetallic cores were assigned to sense wavelengths close to the localized surface plasmon resonance of monometallic NP shell to produce heat which not only can increase the surrounding temperature over the upper critical solubility temperature of polymer to open its valves and promote drug diffusion but also can kill cancerous cells through photothermal effects with increase in environment temperature by nearly 18°C after about 5 min radiation. The bimetallic NPs were shown good reusability even after 5 heating/cooling cycles, and the efficiency of both photothermal/chemotherapic procedures can be modulated by manipulating carrier's concentration and radiation time. In addition, the cytotoxicity of drug-free nanocarriers on normal L929 fibroblast and letrozole-loaded nanocarriers on MDAMB 231 breast-cancer cell lines were investigated in the absence/presence of laser radiation. Finally, the prepared nanocomposites were exhibited switchable on/off drug release in 2 buffered solutions (pH 5.5 and 7.4) with light actuation. The results revealed that the prepared nanocarriers can be served as efficient delivery platforms for remote-control chemophotothermal synergistic cancer therapy.

Switchable on/off drug release from gold nanoparticles-grafted dual light- and temperature-responsive hydrogel for controlled drug delivery.

A switchable dual light- and temperature-responsive drug carrier using gold nanoparticles (Au NPs)-grafted poly(dimethylacrylamide-co-acrylamide)/poly acrylic acid [P(DMA-co-AAm)/PAAc] hydrogel was prepared by free radical polymerization procedure using N,N-methylenebisacrylamide as cross-linker and ammonium persulfate as initiator. Initial P(DMA-co-AAm) hydrogel and uniformly-distributed stable Au NPs, prepared by reduction of hydrogen tetrachloroaureate (III) hydrate in the presence of trisodium citrate, were synthesized separately. Then, the prepared P(DMA-co-AAm) and Au NPs were added to an acrylic acid solution along with the cross-linker and initiator to prepare PAAc hydrogel within the mixture. This improves the swelling ratio and stabilizes Au NPs in networks. Furthermore, a cross-linked P(DMA-co-AAm-co-AAc) random hydrogel was also prepared with the same monomer compositions as the above hydrogel for comparison of their properties. Then, swelling, thermal sensitivity and thermal and optical switching properties of the prepared hydrogels were investigated in two acidic (pH=1.2) and neutral (pH=7.4) buffered solutions to simulate stomach and intestine body conditions. Finally, loading and cumulative release (%) of ofloxacin antibiotic as model drug were considered in both thermal and optical switching conditions. Based on these results, pulsatile release vehicle was obtained which have the "on" state at higher temperatures and the "off" state at lower temperatures.

Laser-assisted triggered-drug release from silver nanoparticles-grafted dual-responsive polymer.

Laser assisted drug release from a synthesized plain polymer composed of poly (butyl methacrylate-co-acrylamide-co-methacrylic acid) [P(BMA-co-AAm-co-MAA)] and a metallo-polymer composed of silver nanoparticles (Ag NPs) grafted plain polymer (the nanocomposite) were studied to investigate their capability to serve as drug carriers. Positive temperature dependent swelling changes were observed for both carriers and their thermal sensitivity and thermal and optical switching properties were investigated in two buffered solutions. An acidic solution with pH=1.2 to simulate stomach body condition and a neutral solution with pH=7.4 to simulate intestine condition. Reversible phase transition (collapsing/swelling) with fast response time in the order of few seconds were observed by applying heat or by applying light radiation at the surface plasmon resonance wavelength of the attached NPs. Finally, cumulative release (%) of ofloxacin antibiotic as a model drug was investigated for both thermal and optical switching conditions. Based on these results, pulsatile release was observed which have the "on" and "off" states at higher and lower temperatures with respect to their volume-phase transition temperatures respectively.

Dispersive micro-solid phase extraction using magnetic nanoparticle modified multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for sensitive determination of lomefloxacin and ofloxacin from biological samples.

A dispersive micro-solid-phase extraction (D-µ-SPE) procedure coupled with surfactant-enhanced spectrofluorimetric detection was developed for determination of ofloxacin and lomefloxacin from biological and environmental samples. The D-µ-SPE procedure was performed using magnetic Fe3O4 nanoparticle grafted multi-walled carbon nanotube as an efficient adsorbent. The main factors affecting the signal enhancement (including surfactant concentration and pH) and extraction efficiency (including pH, extraction time, sample volume, amount of magnetic adsorbent, and desorption conditions) were investigated in detail. Under the optimized conditions, the calibration curves were linear (R(2)˃0.9995) over the concentration range of 50-450 ng mL(-1) with detection limits (LOD) of 12 and 15 ng mL(-1) for ofloxacin and lomefloxacin respectively. The relative standard deviation (RSD %) of 1.9 and 2.1% (C=100 ng mL(-1), n=5) and the enrichment factor of 192 and 188 were achieved for ofloxacin and lomefloxacin respectively. Finally, the method was successfully applied to the extraction and preconcentration of these drugs in biological (plasma and urine) samples.

Surfactant-enhanced spectrofluorimetric determination of total aflatoxins from wheat samples after magnetic solid-phase extraction using modified Fe3O4 nanoparticles.

The extraction and preconcentration of total aflatoxins (including aflatoxin B1, B2, G1, and G2) using magnetic nanoparticles based solid phase extraction (MSPE) followed by surfactant-enhanced spectrofluorimetric detection was proposed. Ethylene glycol bis-mercaptoacetate modified silica coated Fe3O4 nanoparticles as an efficient antibody-free adsorbent was successfully applied to extract aflatoxins from wheat samples. High surface area and strong magnetization properties of magnetic nanoparticles were utilized to achieve high enrichment factor (97), and satisfactory recoveries (92-105%) using only 100mg of the adsorbent. Furthermore, the fast separation time (less than 10 min) avoids many time-consuming cartridge loading or column-passing procedures accompany with the conventional SPE. In determination step, signal enhancement was performed by formation of Triton X-100 micelles around the analytes in 15% (v/v) acetonitrile-water which dramatically increase the sensitivity of the method. Main factors affecting the extraction efficiency and signal enhancement of the analytes including pH of sample solution, desorption conditions, extraction time, sample volume, adsorbent amount, surfactant concentration and volume and time of micelle formation were evaluated and optimized. Under the optimum conditions, wide linear range of 0.1-50 ng mL(-1) with low detection limit of 0.03 ng mL(-1) were obtained. The developed method was successfully applied to the extraction and preconcentration of aflatoxins in three commercially available wheat samples and the results were compared with the official AOAC method.

Application of dispersive liquid-liquid microextraction coupled with vortex-assisted hydrophobic magnetic nanoparticles based solid-phase extraction for determination of aflatoxin M1 in milk samples by sensitive micelle enhanced spectrofluorimetry.

An efficient, simple and fast low-density solvent based dispersive liquid-liquid microextraction (LDS-DLLME) followed by vortex-assisted dispersive solid phase extraction (VA-D-SPE) has been developed as a new approach for extraction and preconcentration of aflatoxin M1 in milk samples prior to its micelle enhanced spectrofluorimetic determination. In this LDS-DLLME coupled VA-D-SPE method, milk samples were first treated with methanol/water (80:20, v/v) after removing the fat layer. This solvent was directly used as the dispersing solvent in DLLME along with using 1-heptanol (as a low-density solvent with respect to water) as the extracting solvent. In VA-D-SPE approach, hydrophobic oleic acid modified Fe3O4 nanoparticles were used to retrieve the analyte from the DLLME step. It is considerably that the target of VA-D-SPE was 1-heptanol rather than the aflatoxin M1 directly. The main parameters affecting the efficiency of LDS-DLLME and VA-D-SPE procedures and signal enhancement of aflatoxin M1 were investigated and optimized. Under the optimum conditions, the method was linear in the range from 0.02 to 200 µg L(-1) with the correlation coefficient (R(2)) of 0.9989 and detection limit of 13 ng L(-1). The intra-day precision was 2.9 and 4.3% and the inter-day precision was 2.1 and 3.3% for concentration of 2 and 50 µg L(-1) respectively. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method.

Gold nanoparticles grafted modified silica gel as a new stationary phase for separation and determination of steroid hormones by thin layer chromatography.

A new thin layer chromatographic layer using gold nanoparticles grafted 3-triethoxysilyl propylamine modified silica gel (Au NPs-APTS modified silica gel) was developed as a stationary phase for separation and determination of two steroid hormones, namely progesterone and testosterone. Acetone-n-hexane 25:75 (v/v) was used as the mobile phase, and the results were compared with those obtained using plain (i.e., unmodified) silica gel plates. Some chromatographic parameters used for separation of the two steroids on an Au NPs-APTS modified silica gel plate as well as on a plain silica gel plate, including ΔRF, separation factor (α), and resolution (RS), were evaluated and compared. The reproducibility of RF values was also determined by analysis of the two steroids in 7 consecutive days on both plates. Validity of the method was investigated, and a wide linear range of 1-200 ng per spot, and low detection limits of 0.16 ng and 0.13 ng per spot, low quantification limits of 0.51 ng and 0.40 ng per spot, and good precision (expressed as percent relative standard deviation) lower than 3.1% and 2.7% were obtained for progesterone and testosterone, respectively. As the results revealed, the proposed method is rapid and sensitive, and it is applicable to separation and determination of progesterone and testosterone in biological matrices such as urine samples.

Magnetic pH-responsive poly(methacrylic acid-co-acrylic acid)-co-polyvinylpyrrolidone magnetic nano-carrier for controlled delivery of fluvastatin.

A novel pH-responsive polymer, poly(methacrylic acid-co-acrylic acid)-co-polyvinyl-pyrrolidone (polymeric nano-carrier) was synthesized and used for encapsulation of 3-aminopropyl triethoxysilane modified Fe3O4 nanoparticles to prepare a new magnetic nano-carrier. The loading and release characteristics of both polymeric and magnetic nano-carriers were investigated using fluvastatin as the model drug. The loading behavior of the carriers was studied by varying concentration of fluvastatin in aqueous medium at 25°C and their release was followed spectrophotometrically (at 304 nm) at 37°C in three different solutions (buffered at pH1.2, 5.5 and 7.2) to simulate gastric and intestine medium. The effect of different parameters on the release of fluvastatin such as the amount of methacrylic acid monomer, cross-linker amount, initiator amount, and magnetic nanoparticles content was also studied. Considering the release kinetics and mechanism of the magnetic nanocarrier besides swelling behavior study of the polymeric nano-carrier reveal Fickian pattern and diffusion controlled mechanism for delivery of fluvastatin.

Magnetically assisted solid phase extraction using Fe3O4 nanoparticles combined with enhanced spectrofluorimetric detection for aflatoxin M1 determination in milk samples.

A novel, facile and inexpensive solid phase extraction (SPE) method using ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol grafted Fe(3)O(4) nanoparticles coupled with spectrofluorimetric detection was proposed for determination of aflatoxin M1 (AFM1) in liquid milk samples. The method uses the advantage fluorescence enhancement by ß-cyclodexterin complexation of AFM1 in 12% (v/v) acetonitrile-water and the remarkable properties of Fe(3)O(4) nanoparticles namely high surface area and strong magnetization were utilized to achieve high enrichment factor (57) and satisfactory extraction recoveries (91-102%) using only 100 mg of magnetic adsorbent. Furthermore, fast separation time of about 15 min avoids many time-consuming column-passing procedures of conventional SPE. The main factors affecting extraction efficiency including pH value, desorption conditions, extraction/desorption time, sample volume, and adsorbent amount were evaluated and optimized. Under the optimal conditions, a wide linear range of 0.04-8 ng mL(-1) with a low detection limit of 0.015 ng mL(-1) was obtained. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method.

Magnetic solid phase extraction of mefenamic acid from biological samples based on the formation of mixed hemimicelle aggregates on Fe(3)O(4) nanoparticles prior to its HPLC-UV detection.

A novel and sensitive solid phase extraction method based on the adsorption of cetyltrimethylammonium bromide on the surface of Fe3O4 nanoparticles was developed for extraction and preconcentration of ultra-trace amounts of mefenamic acid in biological fluids. The remarkable properties of Fe3O4 nanoparticles including high surface area and strong magnetization were utilized in this SPE procedure so that a high enrichment factor (98) and satisfactory extraction recoveries (92-99%) were obtained using only 50mg of magnetic adsorbent. Furthermore, a fast separation time (about 15min) was achieved for a large sample volume (200mL) avoiding time-consuming column-passing process of conventional SPE. A comprehensive study on the parameters effecting the extraction recovery such of the amount of surfactant, pH value, the amount of Fe3O4 nanoparticles, sample volume, desorption conditions and ionic strength were also presented. Under the optimum conditions, the method was linear in the 0.2-200ngmL(-1) range and good linearity (r(2)>0.9991) was obtained for all calibration curves. The limit of detection was 0.097 and 0.087ngmL(-1) in plasma and urine samples, respectively. The relative standard deviation (RSD %) for 10 and 50ngmL(-1) of the analyte (n=5) were 1.6% and 2.1% in plasma and 1.2% and 1.9% in urine samples, respectively. Finally, the method was successfully applied to the extraction and preconcentration of mefenamic acid in human plasma and urine samples.

Magnetic nanoparticles solid phase extraction for determination of ochratoxin A in cereals using high-performance liquid chromatography with fluorescence detection.

A new, simple, fast, and environmental friendly sample preconcentration technique based on the modified Fe3O4 nanoparticles has been developed for extraction, and determination of ochratoxin A (OTA). Magnetic nanoparticles were coated with 3-(trimethoxysilyl)-1-propanethiol and modified by ethylene glycol bis-mercaptoacetate. Transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry were used to characterize the adsorbents and the main parameters affecting the extraction and desorption efficiencies, such as pH of sample solution, sample volume, desorption conditions, extraction and desorption times, salt addition, and co-existing interferences have been investigated and established. Under optimal conditions, OTA was extracted and analyzed using high performance liquid chromatography with fluorescence detection. The mobile phase consists of acetonitrile:water:acetic acid (99:99:2, v/v/v) and fluorescence detection was performed with excitation and emission wavelengths at 333 and 477nm, respectively. An enrichment factor of 24 was achieved for OTA with relative standard deviation of <7%. The proposed method was applied to twenty samples of cereals (rice, wheat, and corn). The limits of detection of 0.06, 0.03, and 0.05ngmL(-1) and limits of quantitation of 0.19, 0.11, and 0.15ngmL(-1), were found for rice, wheat, and corn samples, respectively. The recoveries of OTA for spiked samples were ranged from 87 to 93%.

HPTLC-Densitometric Determination of Cetirizine and Montelukast Analysis in Combined Tablet Dosage Forms.

A simple, accurate and rapid high performance thin layer chromatography (HPTLC)- densitometric method was developed for separation and determination of cetirizine (CET) as a long acting antihistamine and montelukast (MON) as an antileukotriene in pharmaceutical dosage forms. The compounds were separated on silica gel 60 F254 HPTLC plates using a mixture of ethyl acetate : methanol : ammonia solution (25%) (14 : 3 : 2 v/v/v) as mobile phase. The plates were developed vertically up to a distance of 80 mm. Compact spots of both cetirizine (Rf = 0.30 ± 0.01) and montelukast (Rf = 0.52 ± 0.02) were obtained. UV detection was performed at 230 nm. Quantitative analysis was performed by absorbance densitometry using peak area. The method was validated in terms of linearity, precision, accuracy, limit of detection (LOD), and limit of quantification (LOQ). The calibration curves were linear in the range of 40-2000 ng spot(-1) for cetirizine and 120-1000 ng spot(-1) for montelukast. For MON, recovery varied in range of 99.20-100.88% with RSD ranging from 1.02 to 1.90% and for CET, recovery varied in range of 98.13-100.05% with RSD ranging from 1.57 to 1.85%. The LODs were found to be 3.94 and 2.08 ng spot(-1) for CET and MON, respectively. It was observed that the proposed HPTLC method could be used for efficient analysis and monitoring of the CET and MON in combined tablet dosage forms, more convenient with better precision and accuracy than HPLC method.