Advances in Natural Sciences: Nanoscience and Nanotechnology

Ovarian Cancer: Potential biomarkers and nanotechnology based diagnostic tools

2021-12-04T16:17:55+00:00

Due to lack of effective diagnosis, most of the women are diagnosed for ovarian cancer in late stages, which reduces their survival chances. Hence, there is a dire need for development of effective biomarkers and diagnostic strategies that can help in predicting the disease in early stages. Such developments can provide the biomarkers which have the capacity to provide effective results in limited time. They can direct the treatment strategies thereby revolutionising the way ovarian cancer is dealt worldwide. The article focuses on the current diagnostic and prognostic methods available and the potential biomarkers for ovarian cancer detection. These markers are currently being studied and validated. Some of the recent nanotechnological approaches that can be used to develop diagnostic platforms are discussed, which may represent the next generation of ovarian cancer diagnostics and prognostics.

Structural, optical and dielectric studies of wurtzite-type CdS quantum dots green synthesised using Ocimum sanctum (Tulsi) leaf extract

2021-12-12T16:09:44+00:00

Present study reports the synthesis of CdS quantum dots (QDs) using Ocimum sanctum (Tulsi) leaf extract by green chemical method. The as-prepared QDs are characterised by different analytical methods. FTIR analysis indicates that the phytochemicals present in Tulsi leaf extract play an important role in controlling the size of the particle and its morphology. The structural properties and surface morphology studies are carried out by powder XRD and SEM with EDX. PXRD patterns revealed the hexagonal structure (wurtzite) for all CdS QDs. The average crystallite size lies in the range of 3.6–3.0 nm which decreases with the increase of the extract concentration. The lattice parameters of the pure and capped CdS QDs are found to be smaller than that of their bulk analogue. The EDAX study confirms the purity of all the prepared samples. The optical study is done by UV-vis spectroscopy and the particle sizes are estimated by an empirical method, which are in good agreement with those obtained from PXRD analysis. Dielectric constant of the QDs is obtained at room temperature at different frequencies where the frequency dependence is pronounced at the lower frequencies. It is noted that the band gap of the capped CdS QDs systematically increases with the increase of the extract concentration whereas the particles size and dielectric constant of these samples decreases with the increasing amount of the extract.

Effect of graphene oxide concentration on the properties of silicon nanoholes/poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate)/graphene oxide hybrid solar cell

2021-12-12T16:02:42+00:00

We present herein some results on the fabrication and characterisation of n-type silicon nanoholes (SiNH)/poly(3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) containing different graphene oxide (GO) hybrid solar cells. SiNH prepared by a chemical etching method showed a relatively low reflectance below 10% in the incident wavelength range of 300–1000 nm. The effect of GO concentrations on the performance of the hybrid solar cell was also investigated. The solar cell containing 0.5 wt% GO concentration had a maximum power conversion efficiency (PCE) of 9.07%, a V_oc of 0.519 V, a J_sc of 26.85 mA cm⁻² and an FF of 65%, which is about 20% improvement compared to the device without GO (7.53%). The enhancement is attributed to the increase in electrical conductivity of the PEDOT:PSS coating layer due to the addition of the GO.

D2B antibody and its scFvD2B fragment in nanomedicine: promising tools in the theranostics of prostate cancer

2021-12-12T15:58:39+00:00

Prostate cancer (PC) is ranked the sixth deadliest cancers among men. If PC is diagnosed at metastasised stages, traditional surgery and radiation therapy have limitations. In the last few decades, antibody therapy has emerged to deliver radioactive drugs to any metastatic PC tumours; thus, improving theranostics results and prolonged patient's survival via effective targeting of prostate specific membrane antigens (PSMA). Full length anti-PSMA antibody, D2B, and its single chain variable fragment, scFvD2B, have been extensively studied as naked or combined with nanoparticles (NPs) in targeted antibody therapy. Such a combination is considered a current hotspot in research as a means to enhance the delivery, binding specificity, and stability of therapeutic or diagnostic agents. In this review, we summarise and compare data from studies published between 1993 & 2021 to highlight the major outputs from in vivo and in vitro applications of D2B and scFvD2B antibodies in PC theranostics. Special focus is set on gold nanoparticles (AuNPs) as a delivery vehicle given their unique physicochemical and biological properties. Our conclusion supports the use of AuNPs-scFvD2B conjugates in future biomedical approaches.

Green synthesis of Fe-doped Ag-loaded reduced graphene oxide ternary nanocomposite for efficient photocatalytic degradation of toxic dyes

2021-12-12T15:31:02+00:00

The green synthesis of iron nanoparticles (FeNPs) doped and silver nanoparticles (AgNPs) loaded reduced graphene oxide (rGO) (Fe-Ag@rGO) nanocomposite and its applications in methylene blue (MB), malachite green (MG), rhodamine B (RB) degradation were reported. Initially, AgNPs loaded rGO (Ag@rGO) nanocomposites were synthesised simultaneously by an ecological method using Tamarindus indica shell extract as a green reducing agent. Then, the doping of FeNPs into rGO@Ag nanocomposites afforded Fe-Ag@rGO nanocomposite. Interestingly, the finding of this study confirmed that the Fe-Ag@rGO nanocomposites exhibited countless stupendous features in terms of dye degradation. Briefly, the UV-visible spectroscopy and Fourier-transform infrared spectroscopy (FTIR) study confirmed the synthesis of Fe-Ag@rGO nanocomposite. The scanning electron microscopy (SEM) images showed the spherical shape with cross-linked network structures that confirmed the surface modification and synthesis of Fe-Ag@rGO nanocomposite. Finally, the dye degradation potential of the photocatalyst was found to be 97.20%, 98.43%, and 97.33%, for MB, MG, RB, respectively. Herein, the improved photocatalytic performance of the Fe-Ag@rGO was found due to the larger surface area, porous nature, high electron mobility, and synergistic effect of the Fe-Ag@rGO nanocomposite. Additionally, the effective interfacial hybridisation of 'Ag', and doping of 'Fe' on the rGO sheet extended the duration of the photogenerated electron (e^-) hole pairs that can also be contributing to dye degradation. Conclusively, the present experiment provides the new Fe-Ag@rGO nanocomposite to the dye degradation, which could be improved environmental remediation.

Graphene oxide as an effective hole transport material for low-cost carbon-based mesoscopic perovskite solar cells

2021-12-04T16:35:47+00:00

Carbon-based perovskite solar cells (PSCs) are fast developing toward large-scale production. In this study, graphene oxide (GO) was applied as a hole transport material (HTM) for carbon-based mesoscopic PSCs with n-i-p structure. The GO was prepared using a simple Hummer's method, while the carbon counter electrode was deposited using a doctor blade and heated at a temperature of 120 °C. The mesoscopic carbon-based PSCs with various GO dispersion (1.0, 1.5, and 2.0 mg.ml⁻¹) are fabricated and characterised for optimised photovoltaic performance. Consequently, the use of GO as HTM improved the quality of perovskite film by providing perovskite crystals with larger grain size and fewer pinholes. The power conversion efficiency (PCE) of 10.01% was obtained with GO dispersion concentration of 1.0 mg.ml⁻¹, which was significantly higher than a similar device without HTM with a PCE of 8.32%. These results show that GO effectively serves as a promising HTM. Combined with the use of carbon as a replacement for metals as a back-contact electrode, this work demonstrates that the overall material cost for perovskite solar cells could be reduced while maintaining excellent photovoltaic performance.

Effect of electric fields on the electronic and thermoelectric properties of zigzag buckling silicene nanoribbons

2021-12-09T17:18:39+00:00

We investigate the electronic structure and the thermoelectric transport properties of zigzag buckling silicene nanoribbons (BSiNRs) under the effect of external electric fields by means of atomistic simulations. The obtained results show that thanks to the buckling feature, zigzag BSiNRs have a stronger response to a vertical electric field compared to its flat form structure and also single-layer and bi-layer graphene nanoribbons with zigzag edges (GNRs & BGNRs). An inverse is observed in the case of a transverse electric field. Interestingly, the mutual effect when applying simultaneously the vertical and transverse fields induces a larger bandgap compared to individual ones. The mutual effect observed with zigzag BSiNRs is much more pronounced compared to that in zigzag BGNRs since the vertical field has a modest effect on zigzag BGNRs stemming from weak van der Waals interactions between graphene layers. Thermoelectric performance of zigzag BSiNRs is enhanced remarkably with electric fields in which the figure of merit ZT can be tuned to exceed 1. Interestingly, although the mutual impact of two external fields induces the largest Seebeck coefficient, it unveils that the vertical electric field is overall more efficient in enhancing the thermoelectric performance of zigzag BSiNRs. In addition, the enhancement of ZT is demonstrated to stem mainly from a dramatical degradation of the electron thermal conductance around the Fermi level. This study shows that zigzag BSiNRs in combination with external electric fields have favourable advantages for different electronic and thermoelectric applications.

Study on the concentration of gold nanoparticles for antibacterial activity

2021-12-09T17:37:12+00:00

Pure and polymer coated (PVP and PVA) gold nanoparticles (AuNPs) with 0.001 and 0.002 M concentrations were synthesised by chemical method. Transmission electron microscopy (TEM) images showed that the size of nanoparticles is below 50 nm whereas the selected area electron diffraction (SAED) pattern indicated cubic structure with lattice parameter of 4.09 Å for each sample. The absorption bands for all these samples lie between 500 and 550 nm as observed from UV–vis spectra. The photoluminescence (PL) spectra taken at 300 nm excitation wavelength showed emission between 415 and 430 nm whereas the particle size determined from particle size analyser lies below 100 nm for all samples. The ultrasonic velocity measured as a function of temperature showed the decrement above 50 °C for PVP and PVA coated AuNPs. The antimicrobial activity for these above taken concentrations of gold samples showed negative effect, whereas higher concentration of AuNPs of 0.005 M showed the positive effect for gram-positive and gram-negative bacteria.

Preparation of nanocomposites of PbS quantum dots dispersed in MAPbI3 matrix from precursor solution of Pb xanthate

2021-12-12T15:36:32+00:00

Organic-inorganic hybrid perovskites attract attentions because of their unique electro-optical properties which are expected to be applied to various devices. The perovskite compounds are generally prepared from precursor solutions consisting of two materials, AX and BX₂ for ABX₃. Generally, methylammonium lead triiodide (MAPbI₃) perovskite is formed from the precursor solution consisting of methylammonium iodide (MAI) and lead iodide (PbI₂). In this report, we select Pb(-S-C(S)-OR)₂ (lead xanthate, abbreviated as Pb(XT)₂) as the perovskite precursor instead of PbI₂. We found that the precursor solutions consisting of the MAI and the Pb(XT)₂ give nanocomposites consisting of MAPbI₃ and PbS nanomaterials including PbS quantum dot without changing the MAPbI₃ bandgap. In this report, nanocomposites prepared from precursors consisting of Pb(XT)₂/MAI with various ratios are analysed by using XRD, XPS, TG-DTA, TEM and UV/VIS spectroscopy.

Biosynthesis of α-MoO3 nanoparticles and its adsorption performance of cadmium from aqueous solutions

2021-12-12T15:48:11+00:00

Molybdenum (VI) oxide nanoparticles (α-MoO₃ NPs) were green synthesised using buckthorn leaf extract as the reducing and capping agents. The α-MoO₃ NPs were characterised by thermogravimetric analysis, fourier transforms infrared spectroscopy, X-ray diffraction, field emission scanning, and transmission electron microscopy, energy-dispersive x-ray spectroscopy, and Brunauer–Emmett–Teller surface area analysis. The analyses showed the formation of spherical-shaped α-MoO₃ NPs with ∼50 nm mean crystallite size, 3.825 m² g^-1 surface area, and 0.005 cm³ g^-1 total pore volume. The synthesised α-MoO₃ was then applied for adsorption of Cd (II) from aqueous solutions. Optimisation of various adsorption parameters resulted in complete Cd (II) removal under the conditions: 0.1 g α-MoO₃ dose, 60 min contact time, 50 mg l^-1 initial Cd (II) concentration, pH 7 and 298 K. The experimental results were further assessed using different kinetic, isotherm and thermodynamic models. The data were best described by pseudo-second-order (R² = 0.992) and Langmuir (R² = 0.98) models with a maximum adsorption capacity of 57.5 mg g^-1 at optimum conditions. Thermodynamic results indicated that the adsorption process is feasible, spontaneous, and endothermic in nature. Moreover, upon regeneration and interference results, α-MoO₃ is stable and selective for Cd (II) adsorption in presence of other cations. Upon these results, the biosynthesised α-MoO₃ NPs can be used as a selective adsorbent for the efficient removal of Cd (II) from aqueous media.