Nano Express

The field of nanotechnology is being greatly explored by cosmetic industries in order to improve the efficacy of cosmetic products. The increased use of nanomaterials in the field of cosmetics can have two sides as health-related benefits and detrimental effects. This review mainly seeks the pros and cons of the use of nanomaterials in cosmetics along with some examples of nanomaterials that are widely used in cosmetic industries along with different types of nanotechnology-based cosmetic products. The benefits of nanomaterials in cosmetic formulations are huge. Moreover the study regarding the toxic effects on the health also equally matters. This review gives a brief outline of the advantages as well as disadvantages of nanotechnology in cosmetics.

In this article, we report the structural and optical properties of zirconium oxide (ZrO₂) nanoparticles synthesized via chemical co-precipitation method. The effect of calcination temperature on structural and optical properties of ZrO₂ nanoparticles is investigated through XRD, FESEM, EDX, FTIR, UV–Vis absorption, fluorescence emission and life time measurements. XRD spectrum reveals the tetragonal phase at calcination temperature 600 °C and crystallinity of samples increases with calcination temperature. At 800 °C the phase transition from tetragonal to tetragonal-monoclinic mixed phase is noticed. The FESEM images show the particles are of irregular shape and highly agglomerated. FTIR spectra also confirm the formation of ZrO₂ in crystalline phase. From UV–vis absorption spectra it is found a strong quantization and varying band gap with calcination temperature. The change in emission wavelength and intensity with phase change is observed form fluorescence emission spectra. At higher calcination temperature emission intensity is decreased which may be due to the phase change and the formation of surface defects. The life time measurements also reveal the different trap states and life time with calcination temperature.

In this work, two different methods (sol-gel and biosynthesis) were adopted for the synthesis of zinc oxide (ZnO) nanoparticles. The leaf extract of Azadirachta Indica (Neem) was utilized in the biosynthesis scheme. Structural, antibacterial, photocatalytic and optical performances of the two variants were analyzed. Both variants demonstrated a wurtzite hexagonal structure. The biosynthesized variant (25.97 nm) exhibited smaller particles than that of the sol-gel variant (33.20 nm). The morphological analysis revealed that most of the particles of the sol-gel variant remained within the range of 15 nm to 68 nm while for the biosynthesized variant the range was 10–70 nm. The antibacterial assessment was redacted by using the agar well diffusion method in which the bacteria medium was Escherichia coli O157: H7. The zone of inhibition of bacterial growth was higher in the biosynthesized variant (14.5 mm). The photocatalytic performances of the nanoparticles were determined through the degradation of methylene blue dye in which the biosynthesized variant provided better performance. The electron spin resonance (EPR) analysis revealed that the free OH · radicals were the primary active species for this degradation phenomenon. The absorption band of the sol-gel and biosynthesized variants were 363 nm and 356 nm respectively. The optical band gap energy of the biosynthesized variant (3.25 eV) was slightly higher than that of the sol-gel variant (3.23 eV). Nevertheless, the improved antibacterial and photocatalytic responses of the biosynthesized variants were obtained due to the higher rate of stabilization mechanism of the nanoparticles by the organic chemicals (terpenoids) present in the Neem leaf extract.

Zinc Oxide (ZnO) nanoparticles were synthesized by hydrothermal method under different conditions and studied various properties. FTIR studies proved the presence of ZnO bonding and purity of the samples. Grain size was found to be decreased with the increase of reaction temperature and increased with reaction time. TEM images show formation of nanorods under same reaction temperature, also nanoflowers and nanospheres for different temperatures. Intensity of luminescence peaks is found to be changed with variation in interplanar spacing. UV–vis spectra helped to identify the increased photon absorption in particles of bigger size. Change in bandgap value is also observed due to the difference in size of nanoparticles.

Supercapacitors provide remarkable eco-friendly advancement in energy conversion and storage with a huge potential to control the future economy of the entire world. Currently, industries focus on the design and engineering aspects of supercapacitors with high performance (high energy), flexibility (by the use of composite polymer based electrolytes), high voltage (ionic liquid) and low cost. The paper reviews the modelling techniques like Empirical modelling, Dissipation transmission line models, Continuum models, Atomistic models, Quantum models, Simplified analytical models etc. proposed for the theoretical study of Supercapacitors and discusses their limitations in studying all the aspects of Supercapacitors. It also reviews the various software packages available for Supercapacitor (SC) modelling and discusses their advantages and disadvantages. The paper also reviews the Experimental advancements in the field of electric double layer capacitors (EDLCs), pseudo capacitors and hybrid/asymmetric supercapacitors and discusses the commercial progress of supercapacitors as well.

With estimated worldwide cost over $1 trillion just for dementia, diseases of the central nervous system pose a major problem to health and healthcare systems, with significant socio-economic implications for sufferers and society at large. In the last two decades, numerous strategies and technologies have been developed and adapted to achieve drug penetration into the brain, evolving alongside our understanding of the physiological barriers between the brain and surrounding tissues. The blood brain barrier (BBB) has been known as the major barrier for drug delivery to the brain. Both invasive and minimally-invasive approaches have been investigated extensively, with the minimally-invasive approaches to drug delivery being more suitable. Peptide based brain targeting has been explored extensively in the last two decades. In this review paper, we focused on self-assembled peptides, shuttle peptides and nanoparticles drug delivery systems decorated/conjugated with peptides for brain penetration.

Plant mediated synthesis of silver nanoparticles is eco-friendly and of low cost. The synthesis involves a reduction of silver ions and is controlled by several independent factors. In this work, silver nanoparticles (AgNPs) were successfully synthesized using olive stone extract (OSE) and olive mill wastewater (OMW) extract. The nanoparticle synthesis was monitored using the plasmon resonance observed in the UV–Vis absorption spectrum, in which a Voigt profile was fitted. The peak wavelength (λ₀), the peak area (A), and the Full Width at Half Maximum (FWHM) were the fitting parameters and were used as the response. The independent factors were the incubation temperature, the incubation time, the silver nitrate, extract, and sodium hydroxide concentrations. The influence of these factors was investigated 'two factor at a time', using interaction plots. Strong interaction was observed between all factors, with sodium hydroxide to have a crucial role. The optimum conditions for silver nanoparticle formation were a) OSE (1% v/v), AgNO₃ (2 mM), and NaOH (0.2 mM), and b) OMW (2% v/v), AgNO₃ (1 mM), and NaOH (7.9 mM), showing an absorption maximum at 414 nm, and 410 nm, respectively. The mean diameter of AgNPs using OMW, measured with Transmission Electron Microscopy was $12.87\pm 4.84$ nm. Both types of AgNPs showed antibacterial action against Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli), using the broth microdilution assay. Both nanoparticle types inhibited bacterial growth up to one dilution higher than reference samples.

The swiftly growing global economies remain the root cause of the soaring demand for oil and gas to satisfy their excessive energy demands, thus making the oil and gas sector one of the most important industrial sectors. Though renewable energy technologies are the more sustainable option, technological advances are required to make them more accessible to the common people. Therefore, due to the limitation of renewable energy technologies, oil and gas continue to be a more viable alternative. Extensive research is being conducted on the applications of nanotechnology to make the upstream, midstream, and downstream processes efficient in the oil and gas sector. Nanomaterials make the activities in processing and transportation more economical, efficient, and environment-friendly than their conventional counterparts. In this review, we have highlighted the need for nanomaterials in oil and gas, for example, in crude oil exploration, including drilling and EOR, separation techniques, refining, transportation, and other related activities. Further, this review summarizes novel nanomaterials developed and used in the activities mentioned above, and at the end, we have briefly described the synthesis mechanism of these nanomaterials. Finally, we emphasize the current challenges and future work prospects in this area of study.

Colloidal quantum dots (QDs) have emerged as transformative materials with diverse properties, holding tremendous promise for reshaping the landscape of photovoltaics and thermoelectrics. Emphasizing the pivotal role of surface ligands, ranging from extended hydrocarbon chains to intricate metal chalcogenide complexes, halides, and hybrid ligands, we underscore their influence on the electronic behavior of the assembly. The ability to tailor interdot coupling can have profound effects on charge transport, making colloidal QDs a focal point for research aimed at enhancing the efficiency and performance of energy conversion devices. This perspective provides insights into the multifaceted realm of QD solids, starting from fundamentals of charge transport through the coupled assemblies. We delve into recent breakthroughs, spotlighting champion devices across various architectures and elucidating the sequential advancements that have significantly elevated efficiency levels.

A user-friendly software PRISA has been developed to determine optical constants (refractive index and extinction co-efficient), dispersion parameters (oscillator energy and dispersion energy), absorption co-efficient, band gap and thickness of semiconductor and dielectric thin films from measured transmission spectrum, only. The thickness, refractive index, and extinction co-efficient of the films have been derived using Envelope method proposed by Swanepoel. The absorption co-efficient in the strong absorption region is calculated using the method proposed by Connel and Lewis. Subsequently, both direct and indirect bandgap of the films is estimated from the absorption co-efficient spectrum using Tauc plot. The software codes are written in Python and the graphical user interface is programmed with tkinter package of Python. It provides convenient input and output of the measured and derived data. The software has a feature to cross check the results by retrieving transmission spectrum using the values of refractive index, extinction co-efficient, and thickness obtained from Envelope method. The performance of the software is verified by analyzing numerically generated transmission spectra of a-Si:H amorphous semiconductor thin films, and experimentally measured transmission spectra of electron beam evaporated HfO₂ dielectric thin films as examples. PRISA is found to be much simpler and accurate as compared to the other freely available softwares. To help researchers working on thin films, the software is made freely available at https://www.shuvendujena.tk/download.

Microalgae cultures have an excellent ability to capture CO₂ and produce high, medium, and low valuable biocompounds such as proteins, carbohydrates, lipids, pigments, and polyhydroxyalkanoates; those compounds have shown excellent properties in the pharmaceutical, cosmetic, food, and medical industries. Recently, the supplementation of carbon dots (CDs) in autotrophic microalgae cultures has been explored as a new strategy to increase light capture and improve photoluminescence, which in turn enhances biomass growth and biocompounds production. In this work, we synthesized CDs through a simple carbonization method using orange juice as a natural precursor. The green synthesized CDs were analyzed in detail through characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), UV–visible, fluorescence spectroscopy, and ζ potential analysis. Moreover, CDs were added to Chlorella vulgaris to analyze the response under different photoperiod cycles and CDs dosages. The optimal results were obtained with the addition of 0.5 mg l⁻¹ of CDs under a photoperiod cycle of 16 h:8 h (light:dark). In these conditions, a maximum biomass production of 2.12 g l⁻¹ was observed, which represents an enhancement of 112% and 17% in comparison to the control samples under the photoperiod of 12 h:12 h and 16 h:8 h (light/dark), respectively. Furthermore, the production of lipids, proteins, and carbohydrates was significantly increased to 249 mg g⁻¹, 285 mg g⁻¹, and 217 mg g⁻¹ dry weight, respectively. These results suggest that the addition of CDs enhances cell growth and increases the production of lipids and proteins, being a strategy with great potential for the food and pharmaceutical industries.

ZnO nanostructures have attracted considerable attention because of their physicochemical properties and applications as antibacterial agents, photocatalytic reactions for pollutant removal, and electronics. Hence, efficient production and knowledge of their properties under different synthesis conditions are essential. Biosynthesis has emerged as an excellent growth-directing method for synthesizing nanomaterials, representing a soft and cleaner alternative for their production. In this study, we synthesized different ZnO nanostructures using a soft chemistry method at different growth temperatures, from 200 to 800 °C every 200 °C. The crystalline structure was estudied by x-ray Diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HRTEM). The shape and size were studied by Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM), which revealed a ZnO hexagonal phase with two shapes: nanoparticles (NPs) with irregular shapes and nanorods of different sizes. The optical properties were studied by Raman and UV-visible spectroscopy, and optical absorption measurements showed bandgap tuning of the produced nanostructures. Finally, the magnetic characteristics of the samples demonstrated magnetic anisotropy due to the preference for crystalline formation and the size of the nanoparticles. The magnetic interaction between the two types of NPs increased the diamagnetism associated with the nanorods.

Beta gallium oxide (β-Ga₂O₃) microstructures composed of ∼50 nm nanoparticles were synthesized by the hydrothermal method. Using the Tauc plot method a value of ∼4.9 eV was obtained for the optical band gap of β-Ga₂O₃. TEM and XRD analyses revealed high crystallinity of the β-phase of gallium oxide nanostructures. Since there are few publications for the photocatalytic properties of β-Ga₂O₃ the obtained results contribute to better understanding of the photocatalytic effect of this material on toxic dye red amaranth. Moreover, it is shown that β-Ga₂O₃ is a very efficient photocatalyst leading to high percentage degradation of dyes for relatively short periods. For example, the degradation of red amaranth and rhodamine B toxic dyes under UV light irradiation reached 97% and 100% after 165 and 120 min, respectively.

The recent experimental synthesis of the monolayer γ-GeSe, characterized by its unique Mexican-hat band dispersion, has attracted considerable research interest. However, the exploration of band gap engineering in bilayer γ-GeSe and γ-SnSe through the application of strain and electric fields remains under-investigated. In this study, we demonstrate that both strain and electric fields are effective methods for band gap engineering in bilayer γ-GeSe and γ-SnSe. We have discovered that strain can not only tune the band gap but also induce a transition from an indirect to a direct band gap. Furthermore, it is observed that the band gap of bilayer γ-GeSe and γ-SnSe can be modulated by an electric field, potentially leading to a transition from semiconductor to metal. Our findings suggest that band gap engineering via strain and electric fields is a promising approach for designing nanoelectronic and optoelectronic devices based on bilayer γ-GeSe and γ-SnSe.

The fabrication of heterojunction-based photodetectors (PDs) is well known for the enhancement of PDs performances, tunable nature of photoconductivity, and broadband application. Herein, the PDs based on MoSe₂ and MoSe₂/Bi₂Se₃ heterojunction on sapphire (0001) substrates were deposited using a r.f. magnetron sputtering system. The high-resolution x-ray diffraction and Raman spectroscopy characterizations disclosed the growth of the 2-H phase of MoSe₂ and the rhombohedral phase of Bi₂Se₃ thin films on sapphire (0001). The chemical and electronic states of deposited films were studied using x-ray photoelectron spectroscopy and revealed the stoichiometry growth of MoSe₂. We have fabricated metal-semiconductor–metal type PD devices on MoSe₂ and MoSe₂/Bi₂Se₃ heterojunction and the photo-response measurements were performed at external voltages of 0.1–5 V under near-infrared (1064 nm) light illumination. The bare MoSe₂ PD device shows positive photoconductivity behavior whereas MoSe₂/Bi₂Se₃ heterojunction PD exhibits negative photoconductivity. It was found that the responsivity of MoSe₂ and MoSe₂/Bi₂Se₃ heterojunction PDs is ~ 1.39 A W⁻¹ and ~ 5.7 A W⁻¹, respectively. The enhancement of photoresponse of MoSe₂/Bi₂Se₃ PD nearly four-fold compared to bare MoSe₂ PD shows the importance of heterojunction structures for futuristics optoelectronic applications.

Colloidal quantum dots (QDs) have emerged as transformative materials with diverse properties, holding tremendous promise for reshaping the landscape of photovoltaics and thermoelectrics. Emphasizing the pivotal role of surface ligands, ranging from extended hydrocarbon chains to intricate metal chalcogenide complexes, halides, and hybrid ligands, we underscore their influence on the electronic behavior of the assembly. The ability to tailor interdot coupling can have profound effects on charge transport, making colloidal QDs a focal point for research aimed at enhancing the efficiency and performance of energy conversion devices. This perspective provides insights into the multifaceted realm of QD solids, starting from fundamentals of charge transport through the coupled assemblies. We delve into recent breakthroughs, spotlighting champion devices across various architectures and elucidating the sequential advancements that have significantly elevated efficiency levels.

Emergent functionalities created by applying mechanical stress to flexible devices using SnO₂ microrods and Ga₂O₃/SnO₂-core/shell microribbons are reviewed. Dynamic lattice defect engineering through application of mechanical stress and a voltage to the SnO₂ microrod device leads to a reversible semiconductor-insulator transition through lattice defect creation and healing, providing an effective and simple solution to the persistent photoconductivity (PPC) problem that has long plagued UV semiconductor photosensors. Here, lattice defects are created near slip planes in a rutile-structured microrod by applying mechanical stress and are healed by Joule heating by applying a voltage to the microrod. Nanoscale amorphous structuring makes the Ga₂O₃/SnO₂-core/shell microribbon with a large SnO₂ surface area more sensitive to changes in temperature, while mechanical bending of the wet device improves its sensitivity to adsorbed water molecules. These results illustrate the potential for developing flexible devices with new functionalities by enhancing the intrinsic properties of materials through miniaturization, mechanical stress, and hybridization.

Zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) are emerging metal–organic framework nanomaterials composed of 2-methylimidazole and zinc ions, which are widely used in biomedical fields due to their distinctive features such as high porosity, bioresponsive degradation, and superior biocompatibility. Especially, the advanced research of ZIF-8 NPs in smart drug delivery systems is providing unique insights into the rational design of versatile nanomedicines for the treatment and diagnosis of serious diseases. This article provides a comprehensive review and outlook on ZIF-8 NPs-based smart drug delivery systems (SDDSs) including the synthesis methods, drug loading strategies, surface modification, and stimuli-responsive release. In particular, we focus on the advantages of ZIF-8 NPs-based drug loading strategies between the metal coordination-based active loading and the physical packaging-based passive loading. Finally, the opportunities and challenges of ZIF-8 NPs as smart drug delivery carriers are discussed.

Carbon dots are small carbon-based particles with unique properties that make them useful in various applications. Some advantages include low toxicity, bio-compatibility, excellent photo luminescence, high stability, and ease of synthesis. These features make them promising for biomedical imaging, drug delivery, and optoelectronic devices. Carbon dots derived from plants have several advantages, including their low toxicity, biocompatibility, and renewable sources. They also have excellent water solubility and high stability and can be easily synthesized using simple and low-cost methods. These properties make them promising candidates for various biomedicine, sensing, and imaging applications. Plant-based carbon dots have shown great potential in metal sensing and bio-imaging applications. They can act as efficient sensors for detecting heavy metals due to their strong chelation and fluorescence properties. This article showcases plant-based carbon dots, emphasizing their low toxicity, biocompatibility, renewability, and potential in metal sensing and bio-imaging. It aims to illustrate their versatile applications and ongoing research for broader use. The current investigation explores their full potential and develops new synthesis and application methods.

Functionalized carbon quantum dots (CQDs) show great potential for application in the field of food safety. CQDs have attracted widespread attention in this regard due to the wide range of sources of raw materials for their synthesis, and their good biocompatibility and stable fluorescence. This paper analyses the properties of CQDs and compares with those of conventional semiconductor quantum dots (SCQDs). It analyses the similarities and differences between hydrothermal carbonization, pyrolysis and microwave-assisted synthesis of CQDs, and reviews the principles and methods of functionalization of CQDs through surface modification and doping. Finally, it discusses the applications of functionalized CQDs in food safety, such as detection and sensing, bio-inhibition and photocatalytic degradation, and the mechanisms of detection.