Shumaila Islam

Influence of gold nanoparticles on wound healing treatment in rat model: Photobiomodulation therapy

The aim of this study is to investigate the effect of gold nanoparticles (AuNPs) in photobiomodulation therapy (PBMT) on wound healing process.

Fiber Optic Displacement Sensor for Industrial Applications

Owing to industrial applications, a fiber optic displacement sensor is introduced to determine the concentration of hydrocarbons in water. Hydrocarbon is organic water pollution. It can harm the environment as well as human being. Thus, a reflective configuration technique was developed to study the hydrocarbon concentrations in the range of 0%-20%. To validate the designed system, two concentrations were selected which represent the lower and higher region. In principle, this sensor is using the concept of intensity modulation as a function of displacement. The optimum displacement between the reflecting target and the fiber optic probe was found to be at 1.5 mm for all concentrations. Furthermore, the peak voltage from each fingerprint was found to be inversely proportional to the tested concentration. This implies that the higher concentration of hydrocarbon tends to detect weaker signal. The sensitivity of the fiber optic displacement sensor was found to be 0.12 mV/wt.% with repeatability of 96%. The resolution of the sensor was 0.027 V, with a limit of detection of 0.23%. The linearity index was found to be 0.98 and 1.04 corresponding to 6% and 14% hydrocarbon concentration, respectively. The simplicity and the credibility of such system offer a good opportunity for industrial applications especially in the environmental sector.

Synthesis of optically active bromophenol blue encapsulated mesoporous silica–titania nanomatrix: structural and sensing characteristics

Mesostructured silica-titania (ST) and bromophenol blue encapsulated silica–titania (BPB-ST) nanomatrices are synthesized by sol–gel method at low temperature. FESEM analysis shows uniform crack-free porous surface of ST matrix. EDX mapping analysis shows that the BPB species are uniformly distributed/immobilized throughout the ST matrix lattices. AFM images reveal 45.68 nm thick film with low average surface roughness ~1.27 nm, after encapsulation of BPB dye in ST matrix. TEM analysis exhibits uniform interior titania core and silica shell network, with average particle size 2.4 ± 0.4 nm for ST sample which reduced to 0.8 ± 0.3 nm after BPB encapsulation. Mesoporous high surface area 488 m2/g and pore volume of 0.55 cm3/g encapsulated matrix is found to be beneficial for sensing analysis. Transparent (67%) mesoporous nanoparticles with low refractive index 1.41 is obtained for encapsulated nanomatrix. The synthesized sensing material is fast responsive <1 sec and found to be linear for pH 3–12. High pKa value of 7.57 at 580 nm for ST-BPB leads to the broader sensitivity range, repetitive, easy-to use, and color indication system. The ability to change color in response to external stimulus makes ST-BPB a potential sensing material in food.Graphical abstract

Sugar Detection in Adulterated Honey via Fiber Optic Displacement Sensor for Food Industrial Applications

A fiber optic displacement sensor (FODS) using a transmission technique was developed to detect sugar contents in honey. This was achieved by measuring the output signal of non- and adulterated honey with different addition percentage volumes of sugar (fructose and glucose). Five types of honey samples were adulterated with different percentages of fructose and glucose ranging from 0% to 10%. Blue diode laser at 435 nm was used as a light source in this FODS. The performance of sensor showed that the voltage signal linearly increased with the concentration of adulteration of sugar. In contrast, the refractive index of the adulterated honey is found decreasing with the concentration of sugar. This means the higher sugar contents in adulterated honey the lower is the refractive index leading to high transmission in FODS. Thus, FODS based on a transmission technique has a potential to detect the sugar content in adulterated honey. The simplicity, faster, and cost effective made FODS as a promising technique for food industry.

Determination of Hydrocarbon Level in Distilled Water via Fiber Optic Displacement Sensor

Fiber optic displacement sensor offers a feasible way to detect hydrocarbon level in water. A reflective light intensity modulation technique is accomplished to detect hydrocarbon concentration in the ranges of 0%-20%. The reflective configuration technique enables the sensor to collect output voltage at a different displacement. The output voltage decreases linearly with hydrocarbon level at a corresponding optimized displacement of 1.5 mm. Linearity index close to one indicates that a high confident degree the sensor. Simple in design and low cost, makes this system as a promising sensor for determination of hydrocarbon level in water.

Multilayer crack-free hybrid coatings for functional devices

Abstract. Porous acid catalyzed TiO2 single, SiO2-TiO2 hybrid, and TiO2/SiO2-TiO2/SiO2 multilayer coatings are synthesized and characterized for optical and electro-optical applications. The reflection value is reasonably reduced from the surface of the glass by integrating sol–gel based spin-coated single and multilayer thin films. Structurally, the films show uniform, crack-free, and porous nanofilms with good surface roughness of below 10 nm, which has potential for optical applications. Wide range tunability of refractive index (2.83 to 1.59) with more than 78% optical transparency is observed. The multilayered reflection profile is observed around 0.18%, so these coatings are desirable for optochemical functional devices.

Synthesis and characterization of uncoated and cysteamine-coated gold nanoparticles by pulsed laser ablation

Abstract. Gold nanoparticles and cysteamine-coated gold nanoparticles are physically synthesized using the pulsed laser ablation in liquid technique, which is rapid, simple, and efficient one-step synthesis. UV-Vis analysis shows that the absorption band after cysteamine coating is shifted toward the lower wavelength range around ∼234  nm as compared to gold nanoparticles’ absorption band around ∼520  nm. Moreover, the change in the color of the solution is due to the aggregation of nanoparticles after cysteamine coating. From transmission electron microscopy, cysteamine coating of ∼1  nm thickness on gold nanoparticles is successfully carried out with narrow pore size distributions. Energy-dispersive x-ray spectroscopy analysis confirms the presence of cysteamine coating. Attenuated total reflectance Fourier transform infrared spectroscopy analysis also confirms the bond linkage between gold and cysteamine species.

Sol–gel based thermally stable mesoporous TiO2 nanomatrix for fiber optic pH sensing

AbstractThermally stable acid catalyzed mesoporous titania (TiO2) nanomatrices are obtained by sol–gel method for fiber optic pH sensing. These synthesized nanoparticles are annealed at 300 °C, at two time intervals i.e., 1 h and 2 h, characterized with several analytical techniques such as FE-SEM/EDS, AFM, XRD, FTIR, TGA, and Brunauer–Emmett–Teller (BET) analysis. Microscopic analysis shows that synthesized nanoparticles have crack-free, dense and homogeneous surface with low surface roughness (4.4–5.9 nm). EDS mapping confirms the uniform distribution of Ti in all samples. XRD findings revealed the TiO2 anatase phase. BET analysis shows that the mesoporous synthesized TiO2 nanoparticles have surface areas 169 m2/g and average pore diameter 39.2 Å. However, surface area is decreased to 113 and 102 m2/g and average pore diameter increased up to 62.36 and 68.18 Å after 1 h and 2 h heat treatment, respectively. Furthermore, the sensing activity of phenolphthalein (phph) doped mesoporous TiO2 nanoparticles/matrix is found to be high at pH 12 without any leaching/cracking.

Recycling of pneumatic scrap tyre into nano-crumb rubber by pulsed laser ablation in different pH media

Nano crumb rubber from scrap tyre is synthesized via 1064 nm pulsed Nd:YAG laser ablation in three different pH media i.e. DI-water (pH~6.45), D-limonene (pH~3.47) and NaOH solution (pH~13.41). Field Emission Scanning Electron Microscope (FESEM) results show spherical morphology of crumb rubber with high degree of aggregation in DI-water and in D-limonene. However, dispersion of crumb rubbers is observed in NaOH solution. The smallest particles size is obtained in NaOH solution within the range of 10.9 nm – 74.3 nm. Energy-dispersive X-ray spectroscopy (EDX) and FTIR analysis confirmed the elements distribution and chemical bonding of rubber with DI-water, D-limonene and NaOH solution. The experimental findings shows that pulsed Nd:YAG laser ablation has potential for fabricating nano-crumb rubber in liquid media.

Synthesis of Au-Ag alloy nanoparticles in deionized water by pulsed laser ablation technique

Au-Ag alloy nanoparticles are physically synthesized using rapid, simple and efficient Q-switched Nd:YAG pulsed laser ablation in liquid technique (PLAL). Au and Ag colloidal solutions are separately prepared by 1064 nm laser ablation of metallic target (gold and silver) which is immersed in deionized water. Au-Ag alloy nanoparticles are prepared by irradiating the mixture of Au and Ag colloidal solutions with 532 nm of second harmonic wavelength of Nd:YAG laser at three different ratio, 3:1, 1:1 and 1:3 within different exposure times. The three of plasmon absorption bands of Au-Ag nanoparticles are shifted linearly to the lower wavelength [499.67 nm (3:1), 481.25 nm (1:1), 467.91 nm (1:3)], as compared to plasmon absorption spectra of pure Au (520 nm) and Ag (400 nm). Moreover, the change in colors are also observed from red (Au) and yellow (Ag) to orange, brown and green color due to the Au-Ag alloy formations, respectively. Transmission electron microscopy shows the Ag shell around the inner core of Au spherical metal with broad size distribution due to the three different volume ratio, respectively (1.7 nm, 0.7 nm, 1.4 nm). Energy-dispersive X-ray spectroscopy analysis confirms the presence of Au and Ag elements in Au-Ag alloy nanoparticles without any contaminations. Attenuated total reflectance fourier transform infrared spectroscopy analysis also confirms the homogenous Au-Ag alloys chemical bonding.