Optimization of Fluoroimmunoassay against C-Reactive Protein Exploiting Immobilized-antigen Glass Slide

An optimization experiment for an indirect-competitive (IC) fluoroimmunoassay (FIA) against C-reactive protein (CRP) was conducted exploiting an immobilized-antigen glass slide and an anti-CRP antibody tagged with fluorescent silica nanoparticles (FSNPs). The optimized conditions for the IC FIA were as follows: time and concentration of treatment with glutaraldehyde, 30 min and 1.5 %, respectively; time of reaction with coating antigen and concentration of coating antigen for immobilization, 1 h and 0.1 mg/mL, respectively; concentration of FSNP-anti-CRP antibody conjugate coupled by the biotin-avidin interaction, the bioconjugate, for immune reaction, 0.250 mg/mL; concentration of bovine serum albumin (BSA) for blocking and time of blocking with BSA, 3 % and 30 min, respectively. By using the glass slide, a highly sensitive detection against CRP was possible with the limit of detection below 0.1 ng/mL.     

Application of mesoporous carbon and modified mesoporous carbon for treatment of DMF sewage

Mesoporous carbon (MC) was prepared in soft template, and potassium ferricyanide was added into MC to prepare the modified mesoporous carbon (MMC). TEM, SEM, FT-IR, and N₂ adsorption–desorption were used to characterize the textural properties of mesoporous materials. The BET specific surface area, pore volume, and the pore size of MC and MMC were 607.6321 and 304.7475 m²/g, 0.313552 and 0.603573 cm³/g, and 5.4356 and 7.9227 nm, respectively. The adsorption capabilities of MC and MMC were compared with the silica mesoporous material MCM-41. The influences of different adsorption conditions were optimized. For MC, the optimums of adsorbent dose, DMF initial concentration, rotating speed, and pH were 0.002 mg/50 mL, 200 mg/L, 200 r/min, and 4, respectively. MMC showed the highest DMF adsorption capacity at adsorbent dose 0.002 g/50 mL, DMF initial concentration 1000 mg/L, rotating speed 1000 r/min, pH more than 9, and contact time of less than 20 min. Meanwhile for MC, MMC, Pseudo-second-order equation was used to fit adsorption kinetics data. And adsorption process could be well fitted by Langmuir and Freundlich adsorption isotherms of MC, MMC. The results showed that MMC was a perfect adsorbent for DMF, and it was easy to separation and recycle. The recycling property of MMC was still relatively better than other two adsorbents.     

Influences of Process Variables on Size of Chitosan Microspheres

Chitosan microspheres, with a size range of 20–550 μm, were obtained by using an emulsification–coacervation method. The surface morphology and the structure of microspheres were characterized by scanning electron microscopy and X-ray diffraction. The effects of process variables, including stirring rate, chitosan concentration, emulsifier concentration, and cross-linker (glutaraldehyde) concentration, on the diameter of chitosan microspheres were investigated. The results showed that spherical microspheres, without aggregation phenomena and with a very smooth and uniform surface, were obtained when emulsifier concentration, chitosan concentration, stirring rate, and glutaraldehyde concentration were kept at 0.010–0.025 mL/mL, 0.05–0.20 g/mL, 800–2400 rpm, and 0.5–1.5% (v/v) respectively. The chitosan microsphere crystallinity degree decreased after cross-linking. The microsphere size increased with decreasing of stirring rate, emulsifier, and cross-linker concentration; however, the microsphere size increased with increase of chitosan concentration. This indicated that different diameters of chitosan microspheres can be achieved by controlling process variables.     

Highly Sensitive Optical Biosensor for Thrombin Based on Structure Switching Aptamer-Luminescent Silica Nanoparticles

We describe here the construction of a sensitive and selective optical sensor system for the detection of human α-thrombin. The surface functionalized luminescent [Ru(dpsphen)₃]^4? (dpsphen-4,7-diphenyl-1,10-phenanthroline disulfonate) ion doped silica nanoparticles (SiNPs) with a size ~70 nm have been prepared. The DABCYL (2-(4-dimethylaminophenyl)diazenyl-benzoic acid) quencher labeled thrombin binding aptamer is conjugated to the surface of SiNPs using BS³ (bis(sulfosuccinimidyl) suberate) as a cross-linker, resulting in the conformational change of aptamer to form G-quadruplex structure upon the addition of thrombin. The binding event is translated into a change in the luminescence intensity of Ru(II) complex via FRET mechanism, due to the close proximity of DABCYL quencher with SiNPs. The selective detection of thrombin using the SiNPs-aptamer system up to 4 nM is confirmed by comparing its sensitivity towards other proteins. This work demonstrates the application of simple aptamer-SiNPs conjugate as a highly sensitive system for the detection of thrombin and also it is highly sensitive towards thrombin in the presence of other proteins and complex medium such as BSA.     

Lipid-based nanoparticles as drug delivery system for paclitaxel in breast cancer treatment

Paclitaxel (PTX) is a well-known antitumor drug, widely utilized in the treatment of breast, ovarian, head, and neck tumors, among others. The low aqueous solubility (< 1.0 μg/mL; log P = 3.96) limits its use by intravenous route, and alternatives found for the marketed products are associated with high toxicity. Incorporation of PTX into lipid nanocarriers has been considered an interesting nontoxic alternative for this route, but drug loading is usually low. This study aimed to analyze the influence of the lipid composition and three different lipid nanosystems—solid lipid nanoparticles, nanostructured lipid carriers (NLCs), and nanoemulsion—in PTX encapsulation and its biological response. The three proposed systems were prepared by hot melt homogenization followed by ultrasonication. Among the blank formulations first prepared, NLC had the smallest size (74 ± 1 nm), with negative zeta potential (? 11.4 ± 0.1 mV). The incorporation of 0.10 mg/mL PTX into this NLC formulation yielded high and stable encapsulation (0.089 ± 0.003 mg/mL), also supported by polarized light microscopy and differential scanning calorimetry curves. NLC-PTX was very effective against MCF-7 (IC50 25.33 ± 3.17 nM) and MDA-MB-231 breast cancer cell lines (IC50 2.13 ± 0.21 nM), compared to free PTX (IC50 > 500 nM). In addition, no significant cytotoxicity was found against fibroblast cells. Taken together, these results demonstrated that PTX was successfully incorporated into NLC with appropriate physicochemical characteristics for intravenous administration, suggesting that the use of NLC as vehicle to incorporate PTX may be a promising strategy in the treatment of breast cancer.     

Simultaneous determination of amlodipine besylate and rosuvastatin calcium in binary mixtures by voltammetric and chromatographic techniques

Voltammetric and liquid chromatographic (LC) methods have been developed for the simultaneous determination of amlodipine besylate (AML) and rosuvastatin calcium (ROS) for the first time. Detailed electrochemical behavior and simultaneous voltammetric determination of AML and ROS were investigated in detail using glassy carbon electrode (GCE). High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) were also developed for the comparison. Voltammetric method exhibited linear dynamic responses for the simultaneous assay of AML and ROS in the concentration range between 0.006 and 2.85 μg/mL and between 0.01 and 5.00 μg/mL, with detection limits of 0.001 and 0.003 μg/mL, respectively. On the other hand, LC methods presented a wider linearity range than that of the SWV method between 0.5 and 100 μg/mL with the detection limits of 0.011 and 0.027 μg/mL for AML and 0.034 and 0.042 μg/mL for ROS by UPLC and HPLC techniques, respectively.     

Highly sensitive and selective detection of glutathione using ultrasonic aided synthesis of graphene quantum dots embedded over amine-functionalized silica nanoparticles

Glutathione (GSH) is the most abundant antioxidant in the majority of cells and tissues; and its use as a biomarker has been known for decades. In this study, a facile electrochemical method was developed for glutathione sensing using voltammetry and amperometry analyses. In this study, a novel glassy carbon electrode composed of graphene quantum dots (GQDs) embedded on amine-functionalized silica nanoparticles (SiNPs) was synthesized. GQDs embedded on amine-functionalized SiNPs were physical-chemically characterized by different techniques that included high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction spectroscopy (XRD), UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The newly developed electrode exhibits a good response to glutathione with a wide linear range (0.5–7 µM) and a low detection limit (0.5 µM) with high sensitivity(2.64 µA µM⁻¹). The fabricated GQDs-SiNPs/GC electrode shows highly attractive electrocatalytic activity towards glutathione detection in the neutral media at low potential due to a synergistic surface effect caused by the incorporation of GQDs over SiNPs. It leads to higher surface area and conductivity, improving electron transfer and promoting redox reactions. Besides, it provides outstanding selectivity, reproducibility, long-term stability, and can be used in the presence of interferences typically found in real sample analysis.     

Optical properties of serum albumin water solutions,containing mesoporous silicon particles

The interaction of molecules of bovine serum albumin (BSA) with silicon nanoparticles (SiNPs) was studied in water solutions of them at different pH values. The data of photon correlation spectroscopy and IR spectroscopy of studied solutions indicate the absence of interaction between BSA and SiNPs in the pH range 3–7, which is attested to by the experimentally obtained character of the pH dependence of the translational diffusion coefficient D _t and by the absence of hydrogen bonds between the protein carbonyl groups and the OH groups on the surface of mesoporous silicon nanoparticles. The obtained data may play a leading role in further in vivo application of silicon nanoparticles.     

Dispersion of nanospheres on large glass substrate by amorphous or polycrystalline silicon deposition for localized surface plasmon resonance

Nanosphere lithography is a cost-effective way to fabricate noble metal nanostructures for plasmonics. However, dispersing nanospheres on a large area of glass substrate is a difficulty encountered when transparent substrate is required in applications such as localized surface plasmon resonance or surface enhanced Raman spectroscopy. Because poly(diallyldimethyl ammonium chloride) (PDDA) on silicon surface introduces a force that can disperse nanospheres on silicon, in this article, we modify the glass surface through amorphous or polycrystalline silicon deposition and thus well disperse polystyrene or silica nanospheres over a glass area of more than 2 cm × 2 cm. Transmission loss of the glass substrate caused by amorphous or polycrystalline silicon deposition is analyzed with good agreement to experimental spectra, and localized surface plasmon resonance signals generated from the gold nanostructures fabricated on these substrates are measured and yield a sensitivity of 317 nm/RIU, which prove the feasibility and effectiveness of our method.     

Interaction between protoporphyrin IX and tryptophan silver nanoparticles

Silver nanoparticles (AgNPs) have been intensively studied for several purposes including therapeutic applications in cancer. When prepared with tryptophan and photoreduction, silver nanoparticles (TrpAgNPs) become an alternative to conventional anticancer drugs. In this study, the anticancer activity of synthesized TrpAgNPs against MCF-7 breast cancer cells was evaluated, and the inhibitory concentration (IC50) was found to be ~3.4 mg/mL. Since the protoporphyrin IX (PPIX) concentrations in tumor cells are elevate compared to normal cells, the PPIX-TrpAgNP interaction was studied to investigate if it could contribute for cell apoptosis. The investigation was performed using PPIX solution (0.9 μg/mL) with different TrpAgNP concentrations (from 0 to 13 mg/mL). PPIX was characterized by UV-Vis spectroscopy, steady-state and time-resolved fluorescence spectroscopy. The results have shown that the presence of spherical TrpAgNps with 16-nm diameter quench the PPIX fluorescence intensity. This quenching is strongly dependent on the concentration of the TrpAgNPs, and it is caused by a combination of a static and a dynamic process. The chemical binding leads to oxidation of tryptophan and formation of kynurenine, observed in the emission spectra around 470 nm. The strong reduction of the PPIX fluorescence decay lifetime with nanoparticle increasing concentration confirms the quenching processes due to charge transfer from the excited PPIX states to the resonant silver states. The present study confirms the anticancer activity of TrpAgNPs on the human breast cancer cell line (MCF-7) in vitro and indicates that PPIX-AgNP interaction could contribute with MCF-7 apoptosis.

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Graphical abstract Interaction between TrpAgNPs and PPIX

     

Stability–Indicating Spectrofluorimetric Methods for the Determination of Metolazone and Xipamide in Their Tablets. Application to Content Uniformity Testing

A highly sensitive, simple and rapid stability-indicating spectrofluorimetric method was developed for the determination of metolazone (MET) and xipamide (XPM) in their tablets. The proposed method is based on the measurement of the native fluorescence of MET in methanol at 437 nm after excitation at 238 nm and XPM in alkaline methanolic solution at 400 nm after excitation at 255 nm. The fluorescence–concentration plots were rectilinear over the range of 2.0– 20.0 ng/mL for MET and 0.2– 2.0 μg/mL for XPM, with lower detection limits (LOD) of 0.35 ng/mL and 0.02 μg/mL and a lower quantification limit (LOQ) of 1.05 ng/mL and 0.07 μg/mL for MET and XPM, respectively. The method was successfully applied to the analysis of MET and XPM in their commercial tablets and the results were in good agreement with those obtained using the official and comparison methods, respectively. Furthermore, content uniformity testing of the studied pharmaceutical tablets was also conducted. The application of the proposed method was extended to stability studies of MET and XPM after exposure to different forced degradation conditions, such as acidic, alkaline, oxidative and photolytic degradation conditions, according to ICH Guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and photolytic degradation of MET. The apparent first-order rate constants and half-life times were calculated. Proposals for the degradation pathways for both MET and XPM were postulated.     

Removal of oxygen from silicon by electron beam melting

Small amounts of multicrystalline silicon were melted in an electron beam furnace in different experimental conditions in order to investigate the oxygen evaporation behavior during the electron beam melting (EBM) process. The oxygen content level before and after EBM was determined by secondary ion mass spectroscopy. The oxygen content was reduced from 6.177 to 1.629 ppmw when silicon was melted completely at 15 kW with removal efficiency up to 73.6 %. After that, it decreased continually to <0.0517 ppmw when the refining time exceeded 600 s with a removal efficiency of more than 99.08 %. During the melting process, the evaporation rate of silicon is 1.10 × 10^?5 kg/s. The loss of silicon could be reduced up to 1.7 % during oxygen removal process to a desirable figure, indicating EBM is an effective method to remove oxygen from silicon and decrease the loss of silicon.     

Semi-quantitative Surface Enhanced Raman Scattering Spectroscopic Creatinine Measurement in Human Urine Samples

This paper presents the development of a semi-quantitative method of measuring the creatinine biomolecule in human urine by the surface enhanced Raman scattering (SERS) technique. Creatinine is one of the major components of urine and can be used to represent the metabolic and renal function of the human body. The Raman signal of creatinine is enhanced by 50 nm Au nanoparticles. Raman spectra between 1400 and 1500 cm^?1 were analyzed to obtain the relationship between the SERS band area and creatinine concentration. The square of the correlation coefficient is 0.99 in artificial urine over the creatinine range 38.4–153.6 mg/dl. In a human urine experiment, a good linear correlation is observed over the creatinine concentration range 2.56–6.4 mg/dl. The square of correlation coefficient is 0.96.     

Surface disorder in c-Si induced by swift heavy ions

The disorders induced in crystalline silicon (c-Si) through the process of electronic energy loss in the swift heavy ion irradiation were investigated. A number of silicon <1 0 0> samples were irradiated with 65 MeV oxygen ions at different fluences, 1×10¹³ to 1.5×10¹⁴ ions/cm², and characterized by the Raman spectroscopy, the optical reflectivity, the X-ray reflectivity, the atomic force microscopy (AFM) and the X-ray diffraction (XRD) techniques. The intensity, redshift, phonon coherence length and asymmetric broadening associated with the Raman peaks reveal that stressed and disordered lattice zones are produced in the surface region of the irradiated silicon. The average crystallite size, obtained by analyzing Raman spectrum with the phonon confinement model, was very large in the virgin silicon but decreased to<100 nm dimension in the ion irradiated silicon. The results of the X-ray reflectivity, AFM and optical reflectivity of 200–700 nm radiation indicate that the roughness of the silicon surface has enhanced substantially after ion irradiation. The diffusion of oxygen in silicon surface during ion irradiation is evident from the oscillation in the X-ray reflectivity spectrum and the sharp decrease in the reflectivity of 200–400 nm radiation. The rise in temperature, estimated from the heat spike model, was high enough to melt the local silicon surface. The results of XRD indicate that lattice defects have been induced and a new plane <2 1 1> has been formed in the silicon <1 0 0>after ion irradiation. The results of the present study show that the energy deposited in crystalline silicon through the process of electronic energy loss ～0.944 keV/nm per ion is sufficient to induce disorders of appreciable magnitude in the silicon surface even at a fluence of ～10¹³ ions/cm².     

Electron-irradiated n+-Si as hole injection tunable anode of organic light-emitting diode

Traditionally, n-type silicon is not regarded as a good anode of organic light emitting diode (OLED) due to the extremely low hole concentration in it; however, when doped with Au element which acts as carrier generation centers, it can be, as shown in our previous work. In this study, we demonstrate a new kind of carrier generation centers in n⁺-type silicon, which are the defects produced by 5 MeV electron irradiation. The density of carrier generation centers in the irradiated n⁺-Si anode can be controlled by tuning the electron irradiation time, and thus hole injection current in the OLEDs with the irradiated n⁺-Si anode can be optimized, leading to their much higher maximum efficiencies than those of the OLEDs with non-irradiated n⁺-Si anode. For a green phosphorescent OLED with the irradiated n⁺-Si anode, the current efficiency and power efficiency reach up to 12.1 cd/A and 4.2 lm/W, respectively.     

Rapid detection of doxycycline content in duck meat by using silver nanoparticles and alkylphenols polyoxyethylene enhanced fluorescence of europium complex

Doxycycline can coordinate with europium (III) to form europium (III)-doxycycline complex, which can emit the fluorescence characteristic peak of europium (III) at 617 nm in alkaline solution, and the experiment proved that the fluorescence intensity could be further enhanced in the presence of silver nanoparticles and surfactant alkylphenols polyoxyethylene. So this method was applied to detect doxycycline content in duck meat in this research. First, 390 and 617 nm were selected as the optimum excitation wavelength and optimum emission wavelength by three-dimensional fluorescence spectrometry, respectively. Second, the experimental conditions were optimized through single factor experiment. Lastly, the samples of doxycycline concentration range of 0.05–12 mg/L were analyzed under the optimum experimental conditions. A good linear relationship between the doxycycline concentration and the fluorescence intensity was obtained, and the determination coefficient and the root mean squared error of prediction were 0.9982 and 0.4363 mg/L, respectively. This research showed that it was feasible to achieve the rapid detection of doxycycline content in duck meat by using silver nanoparticles and alkylphenols polyoxyethylene enhanced the fluorescence of europium complex.     

Temperature-dependent magnetic and structural ordering of self-assembled magnetic array of FePt nanoparticles

Silicon nanoparticles (SiNPs) can be synthesized by a variety of methods. In many cases these routines are non-scalable with low product yields or employ toxic reagents. One way to overcome these drawbacks is to use one-pot synthesis based on the chemical reduction of micelles. In the following study trichloroalkylsilanes of differing chain lengths were used as a surfactant, and the level of capping, surface bonding and size of the nanoparticles formed has been investigated. FTIR results show that the degree of alkyl capping for SiNPs with different capping layers was constant, although SiNPs bound with shorter chains display a much higher level of Si–O owing to the reaction of the ethanol used in the method with uncapped sites on the particle. SiNPs with longer chain length capping show a sharp Si–H peak on the FTIR, these were heated at reflux with the corresponding 1-alkene to fully cap these particles, resulting in a reduction/disappearance of this peak with a minimal change in the intensity of the Si–O peak. Other techniques used to analyze the surface bonding and composition, XPS, ¹H-NMR, and TEM/EDX, show that alkyl-capped SiNPs have been produced using this method. The optical properties showed no significant changes between the different capped SiNPs.     

Synthesis of an Organic-Inorganic Hybrid Polymeric Material and its Adsorption Performance Characterization Toward Acrylamide

An organic-inorganic hybrid functionalized material was successfully synthesized by a surface molecular imprinting technique combined with a nonhydrolytic sol-gel (NHSG) process using acrylamide (AA) as the template, methacrylic acid as the functional monomer, methacryloxypropyltrimethoxysilane as the cross-linker and magnetic chitosan (CTS) microspheres as the support material. The adsorption ability and selectivity of this material toward AA was characterized. Experimental results showed that the imprinted polymer exhibited better recognition and selective performance toward AA than the nonimprinted polymer (NIP). The saturated binding capacity (Q _max) was 104.68 mg/g, and the equilibrium dissociation constant was 263.16 mg/mL. This prepared material also offered fast kinetics for the adsorption and desorption of AA. After shaking for 5 min, an adsorption capacity of 4.71 mg/g was obtained, and it almost reached the adsorption equilibrium within 90 min.     

Spectrofluorimetric Determination of Terbinafine Hydrochloride and Linezolid in their Dosage Forms and Human Plasma

A highly sensitive, simple and rapid spectrofluorimetric method was developed for the determination of Terbinafine HCl (TRH) and linezolid (LNZ) in their pharmaceutical formulations. The proposed method is based on measuring the native fluorescence of the studied drugs in water at 336 nm after excitation at 275 nm for TRH and 375 nm after excitation at 254 nm for LNZ. The fluorescence–concentration plots were rectilinear over the range of 0.02–0.15 μg/mL for TRH and 0.5–5.0 μg/mL for LNZ. With lower detection limits of 3.0 and 110.0 ng/mL and a lower quantification limit of 9.0 and 320.0 ng/mL for TRH and LNZ, respectively. The method was successfully applied to the analysis of TRH in its commercial tablets, cream, gel and spray formulations and the results were in good agreement with those obtained with the official method. In addition the method was also applied to the analysis of LNZ in its capsule and I.V solution and the results were in good agreement with those obtained with the comparison method. The effect of sensitizers was studied. The method was extended to the determination of the studied drugs in spiked human plasma and the results were satisfactory.