Current Nanoscience - Volume 15, Issue 3, 2019

Background: In recent years, nanotechnology has been known as an integrated knowledge collection which involves various fields. One of the developing fields of nanotechnology which has achieved significant approval is named nanobiotechnology. Nanobiotechnology is a combined form of biology and nanotechnology that incorporates the synthesis of nanoparticles(NPs) that are less than 100nm in size and have following use in biological applications. Objective: The present review study is focused on the variety of nanocarriers and their use in biomedicine and tumor diagnosis and treatment. Results: Conventional therapeutic drugs have exhibited substantial limitations. Therefore, significant attainments have efficiently been made in nanobiotechnology for delivering drugs to the position of action, and reducing their side-effects and limiting radiation therapy toward tumorous sites. So far, several polymeric nanocarriers integrating cytotoxic therapeutics have been made. There is a need for modulation of size and surface features of NPs because unchanged NPs are cleaned from blood circulation. In order to increase biological distribution of therapeutic drugs, irradiation effect, and better tumor imaging, several modified nanocarriers have been developed in optimum size as well as altered external part. Conclusion: In this way, NP is known as an efficient and alternative approach for various aims, including drug delivery, PTT, gene therapy, imaging and diagnosis. There is an anticipation about the contribution of NPs in the field of efficient cancer treatment. Furthermore, NPs may be a proper approach in the treatment of other diseases such as HIV/AIDS. The present review focuses on the variety of nanocarriers and their use in biomedicine and tumor diagnosis and treatment.

Engineering of biocatalysts with the help of immobilization techniques is a worthy approach for the advancement of enzyme function and stability and is finer to the other chemical as well as biological methods. These biocatalysts encapsulation methods actually use very gentle method conditions that hardly affect biocatalysts internal specific biocatalytic activity and this leads to its internment without losing its freedom but restrict the movements related to unfolding. Additionally, enzyme encapsulation somehow imitates their mode of normal incidence within the cells and it also provides secured surroundings for enzymes to the operating parameter changes. According to these advantages, enzyme encapsulation finds enhanced applications in a wide variety of fields such as medicine and sustained or continuous release delivery systems, biosensing, clinic diagnostic, biocatalysts in the manufacture of high-value yield correlated to pharmaceuticals especially in cancer cure, fragrances as well as flavors. This review mainly focuses on the current status of enzyme immobilization using nanocarriers, nanoparticles or polymeric matrix materials, which aim to summarize the latest research on the natural polymer, chitosan based nanoparticles in various enzyme immobilizations.

Background: Direct ethanol fuel cells have gained considerable attention as promising sustainable green power sources for portable electronic devices and automotive propulsion systems. The electrocatalyst is one of the key parameters in DEFCs. However, the current electrocatalyst still suffers from high price due to a relatively large amount of noble metal used, or relatively low activity if non-noble metal was employed. Therefore, the design and fabrication of high-efficient electrocatalyst with low-content of noble metal is still of interest. Methods: Ni(OH)2 nanoflakes supported ultra-low content of Pt (Pt/Ni(OH)2) electrocatalyst was obtained via microemulsion, impregnation and chemical reduction processes. The Pt/Ni(OH)2 electrocatalyst was characterized by SEM, TEM, XRD and FTIR, and its performance for ethanol electro- oxidation was evaluated by cyclic voltammetry, Tafel and current-time curves. Results: TEM result showed that Pt NPs with sizes of ca. 4-6 nm were highly dispersed on the Ni(OH)2 nanoflakes, indicative of the successful preparation of Pt/Ni(OH)2. No peaks related to Pt NPs were observed in the XRD pattern of Pt/Ni(OH)2, revealing a low content and/or high dispersion of Pt NPs. The electrochemical investigation showed that the Pt/Ni(OH)2 electrode presented a superior catalytic performance and stability for ethanol electro-oxidation in alkaline solution. Conclusion: The Pt/Ni(OH)2 electrode with nominal 0.62 wt.% of Pt was successfully synthesized and showed an excellent catalytic activity and stability toward ethanol electro-oxidation mainly due to its porous structure, high dispersion of Pt and formation of NiOOH facilitating oxidation of ethanol. The acetate species was the major product during ethanol electro-oxidation.

Background: Proper detection and subsequent extraction of biological evidence are crucial for crime scene reconstruction. Vacuum metal deposition is currently an effective technique used in latent fingerprint development. However, the established procedures commonly undergo a direct plasma bombardment, a high ablation fluence and/or a high temperature process in vacuum metal deposition system. Method: In this work, electron beam evaporation (EBE) was used to investigate the development of latent fingerprints and subsequent DNA extraction of biological evidence. Gold or copper is preferentially nucleated on the background surfaces rather than the fingerprint residues due to the difference of the nature of the surface, which indicates that the gold / copper and copper agglomerates are binding to the fingerprint valleys not the ridges of the fingerprint, revealing bright patterns with excellent ridge detail clarity on black surfaces. Result: It is demonstrated that the co-extraction of the latent fingerprints and DNA is attributed to electron beam evaporated one-step process with relatively low energy bombarding energetic species and neutral particles, less possibility of contamination and without toxic and fluorine-based gases. Conclusion: Our results demonstrate that EBE is a promising technique for the latent fingerprints and DNA co-extraction.

Background: Carbon nanoparticle (CN) suspensions have been widely used as lymph node tracers in cancers. Here, CN suspension was successfully applied to lymph node dissection. Objective: This study aimed to evaluate the role of CN suspension in identifying lymph nodes and preserving the parathyroid in patients with papillary thyroid cancer (PTC). Method: A total of 96 PTC patients were divided into a CN group (n = 46) and a control group (n = 50). All patients underwent total thyroidectomy with central lymph node dissection from 2014 to 2015. Results: The number of lymph nodes removed in the CN group and the control group was 9.6±2.4 and 7.8±2.2, respectively, and the number of dissected lymph nodes identified as <5 mm in both groups was 4.4±1.3 and 2.4±1.4, respectively. These results were significantly different between the two groups (P < 0.05). However, the number of metastatic lymph nodes was similar in the two groups. In addition, the results further revealed that the level of serum parathyroid hormone (PTH) was significantly lower in the control group than in the CN group on postoperative day 1 and week 1 (P < 0.05), but similar outcomes were observed at postoperative month 1. Conclusion: CN suspension plays an important role in accurately identifying lymph nodes and protecting parathyroid glands. The clinical utilization of CN suspension could increase the accuracy of surgery programs and protect parathyroid function.

Background: With the increasing serious problem of water environment pollution, it is a hot spot to study the high efficient sewage treatment method. Owning to the photosensitization of carbon nanomaterials, carbon doped TiO2 (C-TiO2) has higher photocatalytic activity. Method: Here, we proposed a new method, carbon-assisted method, to prepare C-TiO2 nanomaterials. We first used degreasing cotton as a dispersant to fully absorb the TiCl4 sol. Results: After high-temperature calcination, C-TiO2nanomaterials were obtained. Characterizations results showed that the high specific surface area C-TiO2 nanomaterials in the size of about 50 nm showed a broader light absorption and narrower bandgap spectrum than P25 (commercial TiO2 nanoparticles). Conclusion: The C-TiO2 nanomaterials showed stronger photocatalytic ability than P25.

Background: Spinel ferrites have great scientific and technological significance because of their easy manufacturing, low cost and outstanding electrical and magnetic properties. Nickel ferrite nanoparticles are ferromagnetic material with an inverse spinel structure. They show remarkable magnetic properties and hence have a wide range of applications in magnetic storage devices, microwave devices, gas sensors, telecommunication, drug delivery, catalysis and magnetic resonance imaging. Objective: The aim and objective of this research article is to study the relative effect of NiErxFe2-xO4 nanoparticles and their composites with reduced graphene oxide (rGO) for the photocatalytic degradation reaction and other physical parameters. Method: Rare earth Er3+ substituted NiErxFe2-xO4 nanoparticles were synthesized via the facile wet chemical route. Six different compositions of NiErxFe2-xO4 with varied Er3+ contents such as (x) = 0.00, 0.005, 0.01, 0.015, 0.02 and 0.025 were selected for evaluation of the effect of Er3+ on various parameters of NiFe2O4 nanoparticles. Reduced graphene oxide (rGO) was prepared by Hummer's method and was characterized by UV-Visible spectroscopy, X-ray powder diffraction and Raman spectroscopy. Nano-heterostructures of NiErxFe2-xO4 with rGO were prepared by the ultra-sonication method. Results: X-ray powder diffraction (XRD) confirmed the spinel cubic structure of all the compositions of NiErx- Fe2-xO4 nanoparticles. The photocatalytic degradation rate of methylene blue and congo red under visible light irradiation was found faster in the presence of NiErxFe2-xO4-rGO nanocomposites as compared to bare nanoparticles. It was also investigated that as the Er3+ contents were increased in NiErxFe2-xO4 nanoparticles, the dielectric parameters were largely affected. The room temperature DC-resistivity measurements showed that the Er3+ contents in NiFe2O4 are responsible for the increased electrical resistivity of ferrite particles. The electrochemical impedance spectroscopic (EIS) analysis of NiErxFe2-xO4 nanoparticles and NiErxFe2-xO4-rGO nanocomposites revealed that the ferrite particles possess low conductance as compared to the corresponding composites with graphene. Conclusion: The data obtained from all these characterization techniques suggested the potential applications of the NiErxFe2-xO4 nanoparticles and NiErxFe2-xO4-rGO nanocomposites for visible light driven photo-catalysis and high-frequency devices fabrication.

Background: Electrochemical machining (ECM) is a non-traditional machining method for the metal material based on the principle of anode electrochemical dissolution which has been used in micro/nano fabrication with advantages as not influenced by materials intensity and hardness, no residual stress and no heat treatment born on the surface of the workpiece. Several researches and applications have shown that the surface quality can be improved effectively during the electrochemical machining by using ultrashort pulse power supply. Method: This paper presents a potential of electrochemical machining at the nanometer scale. First, a transient charging double layer mathematical model is developed to describe electrochemical nanostructuring of metallic materials with ultrashort (nanosecond) voltage pulses. And then, by using finite element method (FEM), the analysis model of electrochemical interface between poles is established to give a more realistic analysis of the comparison of transient currents at different separations between the tool and workpiece. Second, a nanoscale electrode is an essential tool in electrochemical nanostructuring. In this paper, electrodes with diameters of several ten to hundred nanometers are successfully prepared by the liquid membrane electrochemical etching. Finally, by using the nanometer scale electrodes above and the ultrashort pulse power supply, several nanostructures with physical dimension of several hundred nanometers are fabricated on nickelbased superalloys. Results: Using the optimal machining parameters, a tool electrode with 230 nm in diameter is obtained from the initial tungsten rod radius of 100 μm. By using 0.05 M H2SO4 solution, the pulse generator with 1μs in period, 100 ns in pulse on-time and 4 V in voltage, a micro/nano groove with the depth of 150 nm and maximum entrance width of 3 μm is obtained. Conclusion: Nanoscale electrodes with diameters of several ten to hundred nanometers is obtained successfully demonstrating that the liquid membrane electrochemical etching is a very effective method to fabricate nanoscale electrode. Several nanostructures with physical dimension of several hundred nanometers can be fabricated successfully demonstrating that ECM with ultrashort pulses is a highly promising nanostructuring technology.

Background: TiO2-based materials can be utilized in both polluted air and wastewater treatments. Ion doping is the most applied modification method, and many kinds of metal ions and nonmetal ions are doped into a TiO2 crystalline skeleton. The hollow spherical photocatalyst can both easily suspend in wastewater under aeration and settle down after treatment to release the water. Methods: The hollow spherical B-TiO2 photocatalyst was prepared by a sol-gel method. Tetrabutyl titanate and tributyl borate were used as the titanium and boron sources. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectrum (FTIR), and N2 adsorption-desorption techniques. Results: The 8%B-TiO2 material is composed of anatase TiO2 when the calcination temperature is below 600°C. The graphical template is burnt out during calcination to leave a hole in the spherical 8%B-TiO2. The BET surface area of the materials declines from 53.2 m2/g at 400°C to 10.6 m2/g at 700°C. High-temperature thermal treatment results in the small surface area and large pore size. The activity of the 8%B-TiO2 materials was studied on adsorption and photocatalytic degradation of RBR X-3B dye. The 8%B-TiO2 sample prepared at 600°C has the maximum activity on RBR X-3B degradation. After five cycles, decoloration efficiency on the 8%B-TiO2 decreases from 100% in the first cycle to 80% in the fifth cycle. Conclusion: Photocatalytic activity of the hollow spherical material depends on calcination temperature with the optimum activity on the sample obtained at 600°C. The hollow spherical 8%B-TiO2 has satisfactory performance for recycling. Photocatalytic degradation of RBR X-3B can be proven by the UV-Vis spectra during the degradation process.

Background: Enzymatic hydrolysis of cellulose is an expensive approach due to the high cost of an enzyme involved in the process. The goal of the current study was to apply magnetic nanomaterials as a support for immobilization of enzyme, which helps in the repeated use of immobilized enzyme for hydrolysis to make the process cost-effective. In addition, it will also provide stability to enzyme and increase its catalytic activity. Objective: The main aim of the present study is to immobilize cellulase enzyme on Magnetic Nanoparticles (MNPs) in order to enable the enzyme to be re-used for clean sugar production from cellulose. Methods: MNPs were synthesized using chemical precipitation methods and characterized by different techniques. Further, cellulase enzyme was immobilized on MNPs and efficacy of free and immobilized cellulase for hydrolysis of cellulose was evaluated. Results: Enzymatic hydrolysis of cellulose by immobilized enzyme showed enhanced catalytic activity after 48 hours compared to free enzyme. In first cycle of hydrolysis, immobilized enzyme hydrolyzed the cellulose and produced 19.5 ± 0.15 gm/L of glucose after 48 hours. On the contrary, free enzyme produced only 13.7 ± 0.25 gm/L of glucose in 48 hours. Immobilized enzyme maintained its stability and produced 6.15 ± 0.15 and 3.03 ± 0.25 gm/L of glucose in second and third cycle, respectively after 48 hours. Conclusion: This study will be very useful for sugar production because of enzyme binding efficiency and admirable reusability of immobilized enzyme, which leads to the significant increase in production of sugar from cellulosic materials.

Background: Silver nanosystems have attracted considerable attention for numerous applications in optoelectronics. The localized surface plasmon of silver nanoparticles embedded into mesoporous titania gives rise to an enhancement of local optical field in the vicinity of Ag nanoparticles which act as efficient light-trapping components, resulting in a visible wavelength-dependent photocurrent. Objective: In this paper, we synthetized patterned nanocomposites formed by titania mesoporous thin films loaded with alkanethiol functionalized Ag nanoparticles and we demonstrated that these stable and accessible nanostructures possess a photocurrent response. Method: Mesoporous thin films are created by combining sol-gel synthesis and template selfassembly. Based on a photolithography technique, silver nanoparticles were selectively photodeposited and then stabilized with octanethiols. Current vs. voltage curves with and without light were compared, where selective light wavelength measurements were achieved by using visible bandpass filters. The optofluidic behavior was evaluated by placing a drop of solutions on the mesoporous film. Results: We demonstrate photocurrent in these mesoporous thin film structures decorated with chemistabilized Ag nanoparticle-based conductive arrays, with significantly enhanced photocurrent peak at the plasmon resonant wavelength around 540 nm. Our findings offer a possibility to perform improved fluid detection with silver-mesoporous titania electronic devices. Conclusion: We showed that an optofluidic sensitive nanocomposite circuit consisting of alkanethiol- functionalized metal nanoparticles embedded in a mesoporous oxide thin film matrix can be produced.

Background: Dye sensitized solar cells (DSSCs) containing two different dyes were recently used for applications to windows. To enhance the efficiency of this type of solar cells by means of the effect of localized surface plasmon resonance (LSPR), we produced gold nanorods (GNRs) with an aspect ratio (a.r.) equal to 3:1 and tos 4:1. With an actual window application in mind, and mainly to prevent corrosion by the redox mediator in the cell, we considered the capping of GNRs before introducing them into the titanium oxide (TiO2) layer of the anode. In particular, we made a double-capping with silica and titania layers for a limited total thickness (i.e., about 6 nm), while still allowing a significant localized LSPR effect despite the increased distance between gold and dye molecules. We documented the different transformations in dimensions of the two types of capped gold nanorods (c-GNRs) due to the effect of sintering. Our aim was to evaluate the influence that these transformations would have on the photovoltaic performances of DSSCs. Methods: We added c-GNRs with a ratio of 2% in w/w to a transparent semiconductor paste, which was doctor bladed on the photoanodes of the co-sensitized solar cells made with commercially available organic sensitizers (L1 or L0) and the squaraine SQ2, which acted as a co-sensitizer. The films had a thickness of about 6 μm and were sintered at 450°C. We used transmission electron microscopy (TEM) analysis to document the transformations, absorbance and absorptance spectra in order to control the effects of these modifications, and transmittance spectra for evaluating the see-through effects. We performed current-voltage, external quantum efficiency (EQE%) and electrochemical impedance spectroscopy (EIS) characterizations of the DSSCs. Results: The semiconductor films with c-GNRs that had GNRs with an a.r. equal to 4:1 (c-GNRs 4:1) had lower absorption and higher transmission as compared to those with GNRs a.r equal to 3:1 (c-GNRs 3:1). Only the c- GNRs 3:1, which retained a similar shape and an a.r. equal to 1.5 after sintering, produced an enhancement in the power conversion efficiency η% (23%), current Jsc (8%), and voltage Voc (2.5%) when used in combination with the dye cocktail containing the organic dye L1. On the contrary, the presence of c-GNRs 4:1 negatively influenced the photovoltaic performances of the cells containing this dye cocktail. The same occurred for both types of c-GNRs with the dye cocktail containing L0. Conclusion: The use of c-GNRs 3:1 could actually improve the efficiency of co-sensitized DSSCs. On the other hand, the transformed dimensions of the c-GNRs 4:1 negatively influenced the photovoltaic characteristics when we used the same concentration of nanoparticles, and a semiconductor paste in small grains (i.e., about 20 nm). We attributed this fact both to a reduced penetration of the dyes in the films and to an inferior plasmonic effect.

Background: Recently, addition of multi-walled-carbon-nanotubes (MWCNTs) has been researched to enhance the rheological properties of magnetorheological (MR) materials of fluid, elastomer and gel. However, there is a lack of study on the effects of MWCNTs on hydrophilic based MR gels (MRG), which have shown a high potential to be applied in smart vibration control systems. Objective: This study is aimed to analyze the effect of MWCNTs on the dynamic stiffness of hydrophilic based MRG. Method: Dynamic stiffness of hydrophilic based MRG was experimentally computed under different magnetic fields and strain amplitudes. Results: Experimental results indicate that the addition of MWCNTs in hydrophilic MRG showed overall degradation of stiffness variation in contradictory to similar research performed on silicon oil based MR gel. Conclusion: These contradictory results reveal that MRGs of hydrophilic base have a different interaction with MWCNTs than hydrophobic oil base.