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This article recaps a variety of interesting catalytic studies based on solubilized and freely movable noble metal nanoparticle catalysts employed for organic reactions in either pure water or water-organic biphasic systems. Small organic ligand-capped metal nanoparticles are fundamentally attractive materials due to their enormous potential as a well-defined system that can provide spatial control near active catalytic sites. The nanoparticle catalysts are first grouped based on the synthetic method (direct reduction, phase transfer, and redispersion) and then again based on the type of reaction such as alkene hydrogenation, arene hydrogenation, nitroaromatic reduction, carbon-carbon coupling reactions, etc. The impacts of various ligands on the catalytic activity and selectivity of semi-heterogeneous nanoparticles in water are discussed in detail. The catalytic systems using polymers, dendrimers, and ionic liquids as supporting or protecting materials are excluded from the subject of this review.

We demonstrate humidity-responsive structural colors with ultrafast rise and recovery times of 20 and 36 ms from a random arrangement of amorphous titania microspheres. A large fraction of the amorphous titania microsphere is shown to be nanoporous, permitting significant changes to the effective permittivity upon water uptake and thereby altering its scattering cross section. Individually, the microspheres are indistinguishable by scattered light in dry and humid environments, but collectively display color contrast in both environments as the incoherent scattering from each particle allows the individual scattering cross sections to be summed in the far-field, exposing smoothly varying spectral features unique to the humidity environment. Time-resolved humidity response measurements of the microspheres show ultrafast response times due to the fast diffusion dynamics of water molecules in the titania nanoporous network. Absence of spatial ordering among microspheres for generating color also facilitates the fabrication of a simple binary humidity-responsive display, optimized in speed and signal at only a monolayer coverage of particles. As the sensing relies on changes in the scattering cross-section, signal detection can be performed using a monochromatic light source that demands little power (30 μW in our demonstration). Such results suggest intriguing possibilities for realizing cheap, simple, ultrafast and power-efficient colorimetric humidity sensors using structural colors from disordered systems.

Single particle Mie calculations of near micron-sized TiO2 particles predict strong light scattering dominating the visible range that would give rise to a white appearance. We demonstrate that a polydisperse collection of these “white” particles can result in the generation of visible colors through ensemble scattering. The weighted averaging of the scattering over the particle size distribution modifies the sharp, multiple, high order scattering modes from individual particles into broad variations in the collective extinction. These extinction variations are apparent as visible colors for particles suspended in organic solvent at low concentration, or for a monolayer of particles supported on a transparent substrate viewed in front of a white light source. We further exploit the color variations on optical sensitivity to the surrounding environment to promote micron-sized TiO2 particles as stable and robust agents for detecting the optical index of homogeneous media with high contrast sensitivities. Su...

Disordered photonic systems as observed in iridescent insects and flowers introduces new pathways for realizing cost-effective and scalable structural colors. In this work, we present a fast-colorimetric humidity sensor derived from a disordered arrangement of polydisperse nanoporous titania microspheres. The sensor relies on changes in the total scattering of the microspheres upon variations in the surrounding humidity. The incoherent scattering from each particle allows the sum of the individual cross sections to determine the total scattering cross section, which converts the individual noisy spectra to a smoothly varying spectrum that gives rise to a saturated color.[1] We show that because the titania microspheres is highly porous with 1~2 nm-sized nanopores, water can diffuse into the particle interior via intracrystalline dynamics, thereby changing the effective permittivity and consequently the scattered color at ultra-fast speeds (sub 50ms). Our results provide a practical route toward achieving cheap, simple, scalable, ultrafast colorimetric humidity sensors using structural colors from disordered nanoporous microspheres [2]. [1] Alam, A-M; Baek K; Son J; Pei Y-R; Kim D-H; Choy J-H; and Hyun J-K. Generating Color from Polydisperse, Near Micron-Sized TiO2 Particles, ACS Appl. Mater. Interfaces, 2017, 9 (28), 23941– 23948 [2] M-Noor, S; Jang, H ; Baek K; Pei Y-R; Alam, A-M; Kim,Y.H; Kim, I.S; Choy, J.H and Hyun J-K. Ultrafast humidity-responsive structural colors from disordered nanoporous titania microspheres. Submitted (2019)

Carbon quantum dots (C-dots) triggered photoluminescent keratin/poly(vinyl alcohol) (PVA)/C-dots nanofibers (NFs) with optical transparency and biocompatibility were prepared by an electrospinning process. The synthesized NFs were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, and spectrofluorometer. C-dots are capable of emitting excitation dependent photoluminescence (PL) emission spectra at room temperature and are nontoxic at reasonably high concentrations. Optically transparent keratin/PVA/C-dots NFs were found to exhibit excitation dependent PL emission at the wavelengths of 488, 535, and 625 nm during excitation at the wavelengths of 360, 480, and 545 nm, respectively, similar to the C-dots. In vitro cytotoxicity tests against NIH-3T3 cell lines revealed a good biocompatible nature of keratin/PVA/C-dots. The results indicated that the fabricated composite NFs mat not only exhibited a well preserved quantum confinement effect of the C-dots along with its transparency but also showed biocompatibility in the living cell environment.

Carbon quantum dots/titanium dioxide (CQDs/TiO2) composite nanofibers were prepared via a facile one step hydrothermal method. Characterization of the samples was carried out by Field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Photoluminescence (PL), and Fourier transformed infrared (FT-IR) spectroscopy. Our study revealed that the photocatalytic efficiency (photodegradation of methylene blue) under visible light irradiation and antibacterial properties (against Escherichia coli) of as prepared composite nanofibers (CQDs/TiO2) are higher than pristine TiO2 nanofibers. The anchored CQDs can both enhance the light absorption and suppress photogenerated electron–hole׳s recombination which results in the enhancement of catalytic and antibacterial properties.

Novel photoluminescence (PL) composite nanofibers (NFs) consist of carbon qunatum dots (CQDs) and polyacrylonitrile blend with polyacrylic acid (PAN/PAA) were fabricated by the coelectrospinning process. The air-dried CQDs containing NFs were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy, spectrofluorometer, and confocal microscopy. CQDs are familiar to emit blue, green and red color depending on the excitation energy. The PAN/PAA/CQDs NFs were found to be optically transparent and exhibited PL properties similar to CQDs. Therefore, blue, green and red color was observed under confocal microscope from the NFs membrane while the sample was excited by 405 nm, 488 nm and 543 nm lasers. The results indicated the well preserved quantum confinement properties of the CQDs inside the polymer matrix without aggregation or substantial quantum dots growth.

Carbon quantum dots (CQD) with down and up-conversion photoluminescence (PL) properties have been synthesized through low-temperature carbonization in a facile one step green method from cabbage as the natural source of carbon. The physiochemical and optical properties of the resultant CQD were performed using transmission electron microscopy, confocal laser scanning microscopy and various spectroscopic methods. The CQD with a quantum yield of 16.5% demonstrated excellent solubility and stability in aqueous media, superior resistance to photo bleaching, consistent PL within a biological pH range, excitation-dependent down conversion and excitation-independent up-conversion PL along with large stock shift behaviour. The purified CQD exhibited low cytotoxicity at higher concentration (500 μg ml−1) during the cell viability experiment against HaCaT cell, an immortalized non-tumerogenic human keratinocyte cell. Subsequently, CQD treated cells displayed three distinguished blue, green and red colours under a confocal microscope during in vitro imaging. Due to the advantages of green synthesis, high biocompatibility, excellent optical properties, low cytotoxicity and good cellular imaging outcome, the cabbage derived CQD showed considerable promise in biomedical applications.

Single particle Mie calculations of near micron-sized TiO

Lignin nano-/microstructures are widely employed for agricultural drug delivery and heavy metal removal from wastewater, and facile low-cost methods of their large-scale production are therefore highly sought after. Herein, uniform-morphology polydisperse lignin microspheres were directly extracted from black liquor by lowering its pH to4 followed by hydrothermal treatment and featured several lignin-typical characteristics, e.g., functional groups, thermal stability, amorphousness, and monolignol units. It was assumed that lignin rearranged and assembled into microspheres of various size, shape, and uniformity depending on pH, temperature, and hydrothermal treatment time. Lignin microsphere extraction efficiency was estimated as 15.87-21.62 g L

A novel and sensitive chemiluminescence (CL) method on a microchip has been presented for the determination of vitamin B1 (VB1). The microchip was fabricated by soft lithographic procedure using polydimethyl siloxane (PDMS) having four inlets and one outlet with a 200 μm wide, 250 μm height, 6 mm diameter and 100 mm long microchannel. The method is based on the enhanced CL intensity of luminol by its oxidation with AgNO3 in the presence of platinum nanoparticles (PtNPs). It was found that the oxidation of luminol with AgNO3 by PtNPs produced strong CL signal at about 425 nm which meant that the luminophore was still 3-aminopthalate. The CL intensity of the luminol–AgNO3–PtNPs system was further increased with the addition of VB1. Under optimum conditions, the CL intensity was increased by increasing the concentration of VB1 in the range of 1.0 × 10−7 to 4.0 × 10−5 mol L−1 with a correlation coefficient of 0.9992. The limit of detection was found to be 4.8 × 10−9 mol L−1 with the relative standard deviation of 1.06%. The method was successfully applied to determine VB1 in vitamin B1 tablets and vitamin B complex tablets. The interaction mechanism of the CL system has been proposed by UV–vis spectra and CL emission spectra.

A sensitive determination of a synthetic fluoroquinolone antibacterial agent, moxifloxacin (MOX), by an enhanced chemiluminescence (CL) method using a microfluidic chip is described. The microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS). The fabricated PDMS microfluidic chip had three-inlet microchannels for introducing the sample, chemiluminescent reagent and oxidant, and a 500 µm wide, 250 µm deep and 82 mm long microchannel. An enhanced CL system, luminol–ferricyanide, was adopted to analyze the MOX concentration in a sample solution. CL light was emitted continuously after mixing luminol and ferricyanide in the presence of MOX on the PDMS microfluidic chip. The amount of MOX in the luminol–ferricyanide system influenced the intensity of the CL light. The linear range of MOX concentration was 0.14–55.0 ng/mL with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) were 0.06 and 0.2 ng/mL respectively. The presented method afforded good reproducibility, with a relative standard deviation (RSD) of 1.05% for 10 ng/mL of MOX, and has been successfully applied for the determination of MOX in pharmaceutical and biological samples. Copyright © 2013 John Wiley & Sons, Ltd.

A sensitive chemiluminescence (CL) method on chip coupled with microfluidic system has been reported for the determination of L-phenylalanine (L-PA). A microfluidic chip device with the detection chamber capable of fast sensing light emitted from the luminol and hydrogen peroxide CL reaction catalyzed by copper sulphate was fabricated for the determination of L-PA. The microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS). The fabricated PDMS microfluidic chip had four inlet microchannels for introducing the sample, chemiluminescent reagent, Cu(II), and oxidant, and a 500 μm wide, 250 μm deep, and 82 mm long microchannel. The detection was based on the enhancement effect of L-PA on the CL signals of luminol–H2O2–Cu2+ system in an alkaline medium. The CL intensity of the system was enhanced linearly with the concentration of L-PA in the range of 1.5 × 10−9–1.2 × 10−7 mol L−1. The limit of detection was found to be 2.4 × 10−10 mol L−1 with the relative standard deviation of 1.8%. The presented method offers a simple, rapid and easy to handle analytical technique in terms of sensitivity, dynamic range and low detection limit for the determination of L-PA in diet soft drinks and pharmaceutical injection samples.

A simple and sensitive spectrofluorimetric method was developed to determine trace amounts of bilirubin (BR) using yttrium (Y3+)–norfloxacin (NFLX) complex as a fluorescence (FL) probe. NFLX can form a stable binary complex with Y3+ and markedly enhances the weak FL signal of the NFLX. The FL intensity of the Y3+–NFLX complex decreased significantly in the presence of BR in a buffer solution at pH=7.2. Under optimal conditions, the FL intensity decreased according to the BR concentration and showed a good linear relationship in the range of 0.03–2.3 μg mL−1 of BR with a correlation coefficient of 0.9988. The limit of detection for the determination of BR was 2.8 ng mL−1 with a relative standard deviation (RSD) of 1.55% for five replicate determination of 0.05 μg mL-1 BR. The presented method offers higher sensitivity with simple instrumentation and was applied successfully in detecting BR at low concentrations.

A rapid and sensitive chemiluminescence (CL) system coupled with a microfluidic chip has been presented to determine vitamin B12 (VB12) based on the reaction of luminol and silver nitrate (AgNO(3)) in the presence of gold nanoparticles (AuNPs). A microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS) having four inlets and one outlet with a 200 μm wide, 250 μm deep, and 100 mm long microchannel. Ag(+) was used as a chemiluminogenic oxidant in this CL reaction which oxidized luminol to produce strong CL signal in the presence of AuNPs. Luminol reacted with AgNO(3) under the catalysis of AuNPs to produce luminol radicals which reacted with dissolved oxygen and emitted CL light. The proposed CL system was applied to determine the amount of VB12 in VB12 tablets and multivitamin. Under the optimum conditions, the CL intensity of the system was increased with the concentration of VB12 in the range of 0.25-100 ng mL(-1) with the correlation coefficient of 0.9982. The limit of detection was found to be 0.04 ng mL(-1) with the relative standard deviation of 1.56 % for five replicate determinations of 25 ng mL(-1) of VB12. The CL reaction mechanism was demonstrated by UV-visible spectra and CL emission spectra.

0.9986) with the limit of detection (3Sb/m) (where Sb is the standard deviation of blank and m is the slop of linear calibration curve) of 6.94 × 10 �10 M. The relative standard deviation (RSD) for 9 repeated measurements of 1.0 × 10 �9 M FA was 1.42%. This method was simple, cost effective, and relatively free of interference from coexisting substances. Successful determinations of FA in pharmaceutical formulation and biological samples with the developed method were demonstrated.

We present the enhancement of luminescence of europium complex, Eu(3+)-ciprofloxacin (CIP), in the presence of silver nanoparticles (Ag NPs) for the CIP determination. The increment of the luminescence intensity of the Eu(3+)-CIP complex with Ag NPs was obtained due to the transfer of resonance energy to the fluorophores through the interaction of the excited-state fluorophores and surface plasmon electron in the metal nano surface. The luminescence intensity of Eu3+ was enhanced by complexation with CIP at 614 nm after excitation at 373 nm corresponding to the 5D0-7F2 transitions of Eu3+ ion. Based on the above phenomenon, a sensitive and rapid spectrofluorimetric method has been developed for the CIP determination. Linearity of the calibration curve was obtained in the range of 2.0 x 10(-10)-1.0 x 10(-8) g mL(-1) with correlation coefficient of 0.9992. The limit of detection of CIP was found to be 1.9 x 10(-11) g mL(-1) with the relative standard deviation (RSD) of 1.19% for 5 replicate measurements of 5.0 x 10(-7) g mL(-1) of CIP. The present method has been successfully applied for CIP determination in pharmaceutical and biological samples.

A new spectroflurometric method for the determination of adenosine disodium triphosphate (ATP) is developed. Fluorometric interaction between ATP and enoxacin (ENX)–Eu 3+ complex was studied using UV–vis and fluorescence spectroscopy. Weak luminescence spectra of Eu 3+ were enhanced after complexation with ENX at 589 nm and 614 nm upon excitation at 395 nm due to energy transfer from the ligand to the lanthanide ion. It was observed that luminescence spectrum of Eu 3+ was strongly enhanced further at 614 nm after incorporation of ATP into the ENX–Eu 3+ complex. Under optimal conditions, the enhancement of luminescence at 614 nm was responded linearly with the concentration of ATP. The linearity was maintained in the range of 1.5×10 −10 –1.15×10 −8 M ( R =0.9973) with the limit of detection (3σ) of 4.71×10 −11 M. The relative standard deviation (RSD) for 9 repeated measurements of 1×10 −9 M ATP was 1.25%. Successful determinations of ATP in soil, milk, and a pharmaceutical formulation with the proposed method were demonstrated.

School of Mechanical Engineering, Kyungpook National University, Daegu 702-701, KoreaReceived September 1, 2011, Accepted November 6, 2011A europium (III)-sensitized, spectrofluorimetric (FL) method is presented for the determination of sparfloxacin(SPAR) using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS). The method is based on thestrong fluorescence (FL) enhancement of SPAR after the addition of Eu

A simple and sensitive chemiluminescence (CL) method coupled with flow-injection technique is proposed to determine naproxen (NAP). The method is based upon the enhancement of the weak CL signal arising from the reaction of Ce(IV) and Na(2)S(2)O(4) with Eu(3+) to form the Eu(3+)-Ce(IV)-Na(2)S(2)O(4) system. The CL intensity was significantly increased by the introduction of NAP into this system in the presence of silver nanoparticles (Ag NPs). Examination of the recorded UV-vis spectra and fluorescence spectra indicated that the energy of the intermediate SO(2)*, which originated from the redox reaction of Ce(IV) and Na(2)S(2)O(4), was transferred to Eu(3+) via NAP and that the process was accelerated by Ag NPs due to their catalytic activity. Under the optimum conditions, the CL intensity was increased with increasing NAP concentration and the correlation was linear (r = 0.9992) over the NAP concentration range of 1-420 ng mL(-1). The limit of detection (LOD) was 0.11 ng mL(-1) with a relative standard deviation (RSD) of 1.15% for 5 replicate determinations of 200 ng mL(-1) NAP. The method was successfully applied to determine NAP in pharmaceutical and biological samples.

We have developed a method for the determination of the three catecholamines (CAs) epinephrine (EP), norepinephrine (NE), and dopamine (DA) at sub-nanomolar levels. It is found that the luminescence of the complexes formed between the CAs and Tb3+ ion is strongly enhanced in the presence of colloidal silver nanoparticles (Ag-NPs). The Ag-NPs cause a transfer of the resonance energy to the fluorophores through the interaction of the excited-state fluorophores and surface plasmon electrons in the Ag-NPs. Under the optimized condition, the luminescence intensity of the system is linearly related to the concentration of the CAs. Linearity is observed in the concentration ranges of 2.5–110 nM for EP, 2.8–240 nM for NE, and 2.4–140 nM for DA, with limits of detection as low as 0.25 nM, 0.64 nM and 0.42 nM, respectively. Relative standard deviations were determined at 10 nM concentrations (for n = 10) and gave values of 0.98%, 1.05% and 0.96% for EP, NE and DA, respectively. Catecholamines were successfully determined in pharmaceutical preparations, and successful recovery experiments are demonstrated for urine and serum samples.

A terbium-sensitized spectrofluorimetric method has been developed for determination of catecholamines such as norepinephrine (NE), epinephrine (EP) and dopamine (DA), using sodium dodecyl benzene sulphonate (SDBS). Fluorescence sensitization of terbium ions (Tb(3+) ) by complexation with catecholamines in the presence of SDBS was observed. The fluorescence intensities of the Tb(3+) -catecholamine complexes were highly enhanced by introducing SDBS with an emission maximum at 545 nm after excitation at 290 nm. The conditions for the complex formation of Tb(3+) -catecholamine were investigated systematically and optimized to determine catecholamines in a serum sample. Under the optimum conditions, the fluorescence intensities of the Tb(3+) -catecholamine complexes were increased linearly with the concentration of NE, EP and DA over the ranges 2.5 × 10(-10) -1.0 × 10(-8) , 2.5 × 10(-10) -1.0 × 10(-8) and 2.5 × 10(-9) -1.0 × 10(-7) g/mL with correlation coefficients of 0.999, 0.999 and 0.9996, respectively. The limits of detection (3δ) of NE, EP and DA were found to be 4.6 × 10(-11) , 7.8 × 10(-11) and 8.38 × 10(-10) g/mL, respectively. Precision of the method was tested at the concentration level of 1.2 × 10(-7) g/mL for five replicate measurements of NE, EP and DA, giving relative standard deviations (RSDs) of 1.41%, 1.23% and 1.89%, respectively. The interaction mechanism of the Tb(3+) -catecholamine complexes system was investigated and presented with ultraviolet absorption spectra. The proposed method has been applied for the quantitative determination of NE, EP and DA in a spiked serum sample and a pharmaceutical preparation sample.

We report on a fluorometric method for the determination of the fluoroquinolones levofloxacin (LEV) and moxifloxacin (MOXI). It is based on the Tb(III)-sensitized luminescence that is plasmonically enhanced by silver nanoparticles (Ag NPs). The emission of the Tb(III) complexes has maximum at 545 nm after excitation at 284 nm and is strongly enhanced in the presence of the colloidal Ag NPs. Under optimum experimental conditions, luminescence intensity increases linearly with the concentration in the range from 4.16 × 10-17-3.59 × 10-15 M of LEV, and from 4.98 × 10-17-2.49 × 10-15 M for MOXI with correlation coefficients of 0.9996 and 0.9996, respectively. The limits of detection are 7.19 × 10-18 M and 8.47 × 10-18 M, respectively, and the relative standard deviations are 1.3 and 1.5% for 5 replicate measurements at 6.08 × 10-14 M of LEV and 5.48 × 10-14 M of MOXI. The method was successfully applied to the determination of LEV and MOXI in pharmaceutical samples, in urine and in serum.

A simple and highly sensitive chemiluminescence method to determine norfloxacin (NFLX) has been proposed by measuring the chemiluminescence (CL) intensities using a flow injection (FI) system. The CL intensity of the luminol- system is strongly enhanced by the addition of Cu (II) in alkaline condition. The CL intensity is substantially increased after the injection of NFLX into the luminol--Cu (II) system. The enhancement effect is attributed to a catalytic effect of Cu (II) due to the interaction with NFLX which forms a complex with the catalyst. Under the optimal conditions, the sensitizing effect of the CL intensity is proportional to the concentration of NFLX in the range of (r = 0.9994) with a detection limit () of . The proposed method had good reproducibility with the relative standard deviation (RSD, n = 5) of 1.6% for of NFLX. The possible reaction mechanism of the CL reaction is also discussed. This method has been successfully applied for the determination of trace amount of NFLX in pharmaceutical preparations and serum samples.

A sensitive and rapid flow-injection chemiluminescence (CL) method has been developed for the determination of gatifloxacin in pharmaceutical preparations and biological samples. The method is based on the enhancing effect of gatifloxacin on CL emission generated by the interaction of Ce (IV) in sulphuric acid and sodium hyposulphite (Na(2)S(2)O(4)) sensitized by sodium dodecyl benzene sulfonate (SDBS). Strong CL emission was observed when gatifloxacin was injected into the Ce (IV) in sulphuric acid and Na(2)S(2)O(4) solution incorporated with SDBS in a flow-cell. Several experimental parameters affecting the CL reaction were investigated and optimized systematically. Under the optimum conditions, it was found that the CL intensity is proportional to the concentration of gatifloxacin in the range of 1.12 × 10(-11)-4.40 × 10(-9) g mL(-1) with a co-relation coefficient of 0.9994. The limit of detection was found to be 4.87 × 10(-12) g mL(-1) and the relative standard deviation (RSD, n=7) was 1.8% for 4 × 10(-8) g mL(-1) of GFLX. The proposed method offers higher sensitivity, wide linear range and better stability without requiring sophisticated instrumentation. Thus, the proposed method has been successfully applied to the determination of gatifloxacin in pharmaceuticals, serum and human urine.

Human hair-based biocomposite nanofibers (NFs) have been fabricated by an electrospinning technique. Aqueous keratin extracted from human hair was successfully blended with poly(vinyl alcohol) (PVA). The focus here is on transforming into keratin/PVA nanofibrous membranes and insoluble property of electrospun NFs. The resulting hair-based NFs were characterized using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning colorimetry (DSC), and thermogravimetric analysis (TGA). Toward the potential use of these NFs after cross-linking with various weight fractions of glyoxal, its physicochemical properties, such as morphology, mechanical strength, crystallinity, and chemical structure were investigated. Keratin/PVA ratio of 2/1 NFs with 6 wt%-glyoxal showed good uniformity in fiber morphology and suitable mechanical properties, and excellent antibacterial activity providing a potential application of hair-based NFs in biomedical field.

Luminescent properties of a terbium (Tb3+)-L-3, 4-dihydroxyphenylalanine (L-dopa) complex by binding to colloidal silver nanoparticles (Ag NPs) have been presented. Luminescence intensity of the L-dopa complex was dramatically enhanced about 6-7 times by introducing Ag NPs. The Ag NPs concentration on the luminescent intensity was regarded as a main factor that balancing between an enhancing and a quenching effect of the Ag NPs. It was observed that changing the concentration of L-dopa causes the change in luminescence intensity. Under the optimized condition, the luminescence intensity of the system was linearly related to the concentration of L-dopa. Based on this observation, L-dopa-Tb3+ complex containing Ag NPs has been applied for the determination of L-dopa in pharmaceutical formulation. Linear responses of luminescence intensity were observed in the concentration range of 0.25 to 1.5 nM (r = 0.9934) of L-dopa with limit of detection 0.042 nM. The performance of the system was tested using 1.0 x 10(-9) M of L-dopa, yielding a precision of 1.21% RSD for nine replicate measurements. The present method has been successfully applied to determine L-dopa in pharmaceutical samples.

A sensitive determination of a synthetic fluoroquinolone antibacterial agent, moxifloxacin (MOX), by an enhanced chemiluminescence (CL) method using a microfluidic chip is described. The microfluidic chip was fabricated by a soft-lithographic procedure using polydimethyl siloxane (PDMS). The fabricated PDMS microfluidic chip had three-inlet microchannels for introducing the sample, chemiluminescent reagent and oxidant, and a 500 µm wide, 250 µm deep and 82 mm long microchannel. An enhanced CL system, luminol-ferricyanide, was adopted to analyze the MOX concentration in a sample solution. CL light was emitted continuously after mixing luminol and ferricyanide in the presence of MOX on the PDMS microfluidic chip. The amount of MOX in the luminol-ferricyanide system influenced the intensity of the CL light. The linear range of MOX concentration was 0.14-55.0 ng/mL with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) were 0.06 and 0.2 ng/mL respectively. The presented method afforded good reproducibility, with a relative standard deviation (RSD) of 1.05% for 10 ng/mL of MOX, and has been successfully applied for the determination of MOX in pharmaceutical and biological samples.

Vitamin B1(thiamin), a water-soluble vitamin of the B complex, consists of a pyrimidine and thiazol ring associated via a methylene bridge. Vitamin B1 is biologically and pharmaceutically important compound which acts as a controlling agent for an organism's normal health and growth. All living organisms use vitamin B1 in their biochemical processes for carbohydrate metabolism and the maintenance of neural activity. Vitamin B1 is used for the treatment and prevention of diseases such as beriberi and neuralgia, and plays a vital role in enzymatic mitochondrial reactions to liberate energy and NADPH production for maintaining cellular redox, glutathione levels, protein sulfhydryl groups, nucleic acid and fatty acid synthesis. The determination of vitamin B1 in clinical analysis, food processing, pharmaceutical and biotechnological processes is thus very important. This chapter examines the development of different spectrofluorimetric methods for the determination of vitamin B1. Such methods have higher sensitivity and selectivity than conventional analysis methods for this purpose.

A sensitive spectrofluorimetric method has been developed for the determination of moxifloxacin (MOX) using europium(III)–MOX complex as a fluorescence probe in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS). The fluorescence (FL) intensity of Eu 3+ was enhanced by complexation with MOX at 614 nm after excitation at 373 nm. The FL intensity of the Eu 3+ –MOX complex was significantly intensified in the presence of SDBS. Under the optimum conditions, it was found that the enhanced FL intensity of the system showed a good linear relationship with the concentration of MOX over the range of 1.8 × 10 −11 –7.3 × 10 −9 g mL −1 with a correlation coefficient of 0.9998. The limit of detection of MOX was found to be 2.8 × 10 −12 g mL −1 with relative standard deviation (RSD) of 1.25% for 5 replicate determination of 1.5 × 10 −8 g mL −1 MOX. The proposed method is simple, offers higher sensitivity with wide linear range and can be successfully applied to determine MOX in pharmaceutical and biological samples with good reproducibility. The luminescence mechanism is also discussed in detail with ultraviolet absorption spectra.

A terbium-sensitized spectrofluorimetric method has been developed for determination of catecholamines such as norepinephrine (NE), epinephrine (EP) and dopamine (DA), using sodium dodecyl benzene sulphonate (SDBS). Fluorescence sensitization of terbium ions (Tb(3+) ) by complexation with catecholamines in the presence of SDBS was observed. The fluorescence intensities of the Tb(3+) -catecholamine complexes were highly enhanced by introducing SDBS with an emission maximum at 545 nm after excitation at 290 nm. The conditions for the complex formation of Tb(3+) -catecholamine were investigated systematically and optimized to determine catecholamines in a serum sample. Under the optimum conditions, the fluorescence intensities of the Tb(3+) -catecholamine complexes were increased linearly with the concentration of NE, EP and DA over the ranges 2.5 × 10(-10) -1.0 × 10(-8) , 2.5 × 10(-10) -1.0 × 10(-8) and 2.5 × 10(-9) -1.0 × 10(-7) g/mL with correlation coefficients of 0.999, 0.999 and 0.9996, respectively. The limits of detection (3δ) of NE, EP and DA were found to be 4.6 × 10(-11) , 7.8 × 10(-11) and 8.38 × 10(-10) g/mL, respectively. Precision of the method was tested at the concentration level of 1.2 × 10(-7) g/mL for five replicate measurements of NE, EP and DA, giving relative standard deviations (RSDs) of 1.41%, 1.23% and 1.89%, respectively. The interaction mechanism of the Tb(3+) -catecholamine complexes system was investigated and presented with ultraviolet absorption spectra. The proposed method has been applied for the quantitative determination of NE, EP and DA in a spiked serum sample and a pharmaceutical preparation sample.