Current Nanoscience - Volume 18, Issue 2, 2022

Viral infection is a worldwide health problem, which has negatively affected global activity in recent years. There is no specific medication for most of the viral infections and the treatments are based on symptom management. Nanoparticles (NPs) in recent years have shown promising antibacterial and antiviral properties, among which metal oxide NPs have shown superiority. In the present study, we aimed to systematically review all available literature supporting the efficiency of zinc oxide (ZnO)NPs in the treatment of viral infections. For this purpose, a systematic literature search was performed in scientific literature databases, including PubMed, Scopus, Web of Science, Science Direct, Ovid, Embase, and Google Scholar by using “viral infections”, “antiviral effects” and “ZnO NPs” in addition to all their equivalent terms as keywords. Due to the lack of human studies, no strict inclusion criteria were defined and all available relevant studies were included. A total of 14 documents that fully met the inclusion criteria were retrieved and used for data synthesis. The results showed that ZnO NPs due to specific physicochemical properties can be a promising approach in developing antiviral agents and nano vaccines, especially against RNA viruses, such as human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus. The most probable antiviral mechanistic pathways of ZnO NPs include blocking the virus entry into the cells and deactivation of the virus through virostatic potential. Based on the findings of the included studies, it is suggested that ZnO NPs and other metal oxide-based NPs may be potential antiviral agents; however, further human studies are required to confirm such efficiency in clinical practice.

Stimuli-triggered nanovectors for drug delivery enhance the clinical efficacy and decrease the toxicity by specifically conveying the drugs to the site of target with a higher specificity and efficiency. Several stimuli were regarded, but light as an exogenous stimulus tenders several benefits in clinical usage like elevated spatial and temporal control economically. A number of photochemical mechanisms have been exploited in design of phototriggered nanocarriers for biomedical applications. Light in conjugation with photosensitizers or imaging agents in nanovectors can be truly rewarding to ensure precise diagnosis, drug delivery and improve therapeutic outcomes. Nanomedicine plays a key role in enhancing therapeutic efficacy and limiting the adverse effects. The review evaluates the multiple nanocarriers such as liposomes, polymersomes, micelles, nanogels etc., which have leveraged the advantages of phototargeting via photothermal, photochemical, photo isomerization and upconversion based activation strategies for efficient drug targeting to intracellular and other regions. The significant benefits and constraints, an overview of the implementation and latest developments for the most popular and recent photoresponsive drug delivery methods are discussed to critically judge its success and limitations and delve upon the possible future perspectives in the field.

Graphene as a nanofiller has gained tremendous importance in polymer nanocomposites for many applications. The attractive properties of graphene related to mechanical, electrical, and thermal domains pose a lucrative means of reinforcing the polymers to obtain the needed properties. The rise in the use of polymers supports this trend and urge researchers to excavate the hidden plethora of nanocomposite materials for multifunctional applications. In this review, an overview is provided on graphene-based materials which have been used extensively in various fields such as batteries, aerospace, automobile, and biomedical fields. With the increasing trend of graphene usage by many researchers as a nanofiller in polymer composites, its types, processing methods are highlighted with suitable applications to assimilate the updates in the development of graphene nanocomposites.

Silicon quantum dots (Si QDs) with unique properties of light, electricity, magnetism, and heat possess the advantages of non-toxicity, environmental protection, and serving as abundant reserves. They are widely used in various fields and have great potential for development. Till now, numerous researchers have reported the research progress of Si QDs or elaborated the behavior mechanism. However, a few comparisons are made on the properties of a quantum dot in different fields and different preparation methods. Besides, the parameters of Si QDs vary greatly in different application fields, which are worthy of comparison. During the current work, we review the research progress and synthesis methods in recent years. The main influencing factors of Si QDs in different preparation methods (physical and chemical) and different application properties (fluorescence detection, solar cell, photocatalyst, and composite) are compared and discussed in detail. Therefore, this paper aims to find promising preparation methods for different application fields and provide a clear direction for researchers to study Si QDs in different directions.

Globally, the maintenance and repair of infrastructure cost billions of dollars and impact the day-to-day life of people. Corrosion of infrastructure and metals used in the manufacture of goods and supplies is a major cause of deterioration in the construction industry. Nanocontainerbased self-healing coatings attract enormous scientific attention as they offer a wide range of applications in conjunction with long-lasting inhibition performance. These coatings prevent the rate of crack progression by releasing active agents from micro/nanocontainers in a controllable manner and heal crack, thereby mitigating corrosion. The potential of such coatings to heal local damage induced by climatic causes or by mechanical damage is a significant contributing factor to their desirability. This review is a comprehensive analysis of nanocontainers used to manufacture self-healing anticorrosive coatings as well as explains their self-healing mechanism. The technique used to develop nanocontainers such as layer-by-layer assembly of layered double hydroxide has been clarified. An attempt has also been made to cover the latest developments in the manufacture of nanocontainermediated self-healing corrosion coatings used in several construction industries.

Background: In this report, the layered g-C3N4/SnS2 composite was successfully fabricated by a facile hydrothermal route. Methods: The ultraviolet-visible spectroscopy data presented that such layered g-C3N4/SnS2 catalysts showed a remarkable visible-light absorption, hence significantly enhancing the catalytic activity. Particularly, the g-C3N4/SnS2 catalysts showed an outstanding catalytic performance for the degradation of methylene blue (~ 98.1%) under visible light irradiation that is much better than that of pure SnS2 (~ 86.7%) and pure g-C3N4 (~ 67.3%). Results: The remarkable photocatalytic performance is ascribed to its layer structure resulting in a large surface area, which not only improves the ion transfer rate but also provides abundant surface reaction sites. Conclusion: Our work demonstrates that the layered g-C3N4/SnS2 can be considered as an exceptional candidate for a highly-efficient photocatalyst.

Background: The current study was conducted to prepare an efficient super-paramagnetic iron oxide nanoparticle (SPIONs) to remove Aeromonas hydrophila from water. Methods: The nanoparticles were synthesized by the co-precipitation method and characterized by DLS, UV-Vis spectrophotometer, FT-IR, XRD, FEG-TEM, and VSM analysis. Results and Discussion: The results showed that the synthesized SPIONs were having a size range of 8-12nm with magnetic property. Bacteria removal efficiency and antibacterial activity of SPIONs were assessed in sterile distilled water by adding different concentrations of SPIONs viz. 0, 6.25, 12.5, 25, 50, 100, 200, 500, and 1000μM with different initial bacterial loads viz. 1×10³, 1×10⁴, 1×10⁵, 1×10⁶, and 1×10⁷ CFU mL−1 at different time intervals 15, 30, 45, and 60 min. At low bacterial load (1×10³ to 1×10⁵ CFU mL−1), 95 to 99.99% of bacteria were removed by low SPIONs concentration (6.25-100μM) by 15min which was increased up to 100% by 30min. However, at high bacterial load (1×10⁶ to 1×10⁷ CFU mL⁻¹), more than 87 to 95% of bacteria were removed by the highest SPIONs concentration (1000μM) by 15min, which was increased above 93 to 99.99% by increasing the exposure time to 60min. At low bacterial load (1×10³ to1×10⁵ CFU mL⁻¹), the effective concentration was 3.21 to 6.42μM at 15-60 min intervals. Meanwhile, the effective concentration at high bacterial load was 267.81 μM at 15min, which was decreased to 104.09 μM with increasing exposure time to 60min. Conclusion: Based on the results, it is concluded that the antibacterial effect against A. hydrophila depends on the concentration as well as the exposure time of SPIONs. A low concentration of SPIONs is sufficient to remove 100% of bacterial load in lower exposure time and increasing concentration of SPIONs increases the antibacterial effect. However, further research requires to find the safe concentration of SPIONs for using it as a novel antibacterial agent for the treatment of aeromonads disease in aquaculture.

Background: Probe sonication and high-speed homogenizer are comparatively costly equipment to fabricate the nanoparticles. Many academic and research institutions cannot afford the procurement and maintenance of such sophisticated equipment. In the present work, a newer idea is conceptualized, which can be adopted by underprivileged research institutions to fabricate solid lipid nanoparticles (SLN) in the absence of sophisticated equipment. The current work describes the pilotlevel trials of this novel approach. This study represents the preliminary proof-of-concept trials for which the Indian patent application (3508/MUM/2015) is filed. Method: A frugal piece of equipment was made using a 50 ml centrifuge tube with conical bottom and a piezoelectric mist maker or humidifier. SLNs were prepared by combining the quasi-emulsion solvent evaporation approach and ultrasonic vibration approach. A quasi-emulsion was composed by the dropwise mixing of the organic solvent containing drug and lipid with an aqueous solution containing surfactant under continuous ultrasonic vibration in the piezoelectric chamber. The size of the droplets was significantly reduced due to piezoelectric ultrasonic vibration. Under the provision of mild vacuum and heat generated by vibration, the organic solvent was evaporated, which leaves behind a suspension of SLN. In the present work, albendazole was selected as a model drug. Various trials with Compritol 888 ATO® and Precirol ATO 5® as a lipid carrier and Tween 80 and Poloxamer 188 as a surfactant were performed. Zeta potential of SLNs was improved by the addition of polyelectrolytes like K2SO4 and Na4P2O7. Result and Conclusion: The ratio of drug to lipid was optimized to 1:4 for the most favorable results. SLNs with a minimum Z-average diameter of 98.59 nm, -21 mV zeta potential, and 34.064 % (SD 10.78, n=9) entrapment efficiency were developed using the Precirol ATO 5 ® as a lipid carrier. The proof of concept for this novel approach is established through the development of Albendazole SLNs. This approach must also be evaluated for the development of polymeric nanoparticles and vesicular formulations. The further sophistication of the frugal equipment may allow more control over the quality of SLNs. This approach will enable underprivileged researchers to prepare nanopharmaceuticals. Researchers and students of such institutions can focus on the application of SLN by resolving the constraint of sophisticated equipment with this novel approach. This novel approach should also be tried for polymeric and vesicular nanopharmaceuticals.

Background: The highly sensitive and selective detection of Cr³⁺ is critical. Objective: We report the development of poly(γ-glutamic acid) (γ-PGA)-functionalized iron oxide nanoparticles (γ-PGA-Fe3O4 NPs) as a magnetic nanosensor for magnetic resonance (MR) detection of trivalent chromium (Cr³⁺) in aqueous solution. Methods: The γ-PGA-Fe3O4 NPs with a mean particle size of 7.3 nm, good colloidal stability and ultrahigh r2 relaxivity (326.8 mM⁻¹s⁻¹) were synthesized via a facile mild reduction approach in the presence of γ-PGA, and used for MR detection of Cr³⁺. Results: Upon exposure to Cr³⁺, the γ-PGA-Fe3O4 NPs aggregated into nanoclusters as verified by dynamic light scattering due to the coordination of Cr³⁺ with γ -PGA side-chain carboxyl groups, resulting in the decrease in their transverse relaxation time. This MR signal change enables detection of Cr³⁺ in a concentration range of 0.4-1 nM. We also show that the γ-PGA-Fe3O4 NPs have an excellent selectivity toward Cr³⁺ and a high recovery percentage of 83.8% or above. Conclusion: This study thus demonstrates that the developed γ-PGA-Fe3O4 NPs may be used as a nanoprobe for MR sensing of Cr³⁺ in water environment.

Background: Nanostructured metal oxides have stimulated tremendous efforts for sightseeing glucose bio-sensing applications. They have been mostly investigated to fabricate highly sensitive, stabilized and ultrafast biosensors. Objective: Fabrication and characterization of glucose biosensors based on zinc oxide (ZnO) nanostructured thin films modified by copper oxide (CuO) nanostructures in order to obtain stabilized ZnO:CuO biosensors with high sensitivity and fast response time. Methods: The components of the investigated biosensors are synthesized using the hydrothermal solgel method by dip-coating the sensing layer on indium tin oxide-coated glass substrates (ITO). The structural and electrical properties of the fabricated biosensors are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and I-V characteristics. Results: SEM micrographs indicate that ZnO nanostructures exhibit an interconnected sheet-like patterns. These sheets are thin and distributed randomly on the ITO substrate. SEM images of ZnO:CuO reveal that the morphology of nanostructured thin films is composed of flower-like patterns. The XRD patterns of ZnO and modified ZnO:CuO thin films subjected to thermal annealing show that thin films exhibit a high degree of crystallinity with minor traces of impurity phases. The biosensors' key parameters are calculated and interpreted by measuring the I-V characteristics to elucidate the sensitivity and reproducibility of measurements performed for various glucose concentrations. Furthermore, the electric current response of ZnO and ZnO:CuO biosensors are found to be linear and quadratic as a function of glucose concentration, respectively. The introduction of CuO into ZnO thin films leads to the enhancement of the sensitivity of the synthesized glucose biosensors for a high degree of precision in measuring glucose levels. Conclusion: Both sensors exhibit average sensitivities in the range (from 1 to 10 μA mM⁻¹ cm⁻²) with quite good reproducibility. The unique property of this sensor is its ability to measure glucose concentrations at neutral pH conditions (i.e. pH = 7) using a simple, low cost and novel sensor design.

Background: Curcumin-stabilized silver nanoparticles (Cur-AgNp) were synthesized by a facile chemical method. The synthesized AgNp was, for the first time, used as a bio-derived corrosion inhibitor for carbon steel in the 1M sulphamic acid medium. Methods: The electrochemical studies via impedance spectroscopy, potentiodynamic polarization, and surface analysis are reported in the communication. The maximum inhibition efficiency of 92.87% was obtained at 800 mgL^-1. Results: The impedance measurements revealed an elevation in the polarization resistance with growth in the inhibitor concentration, which supports the adsorption and inhibition behavior of Cur- AgNp on the steel surface. The inhibitor functioned by adsorption on the steel surface and obeyed the Langmuir kinetic-thermodynamic isotherm with a mixed mode of physical/ chemical adsorption. The potentiodynamic polarization study revealed cathodic predominating behavior. Conclusion: The SEM analysis depicted the development of a protective inhibitor film on the steel substrate, and FTIR-ATR analysis of the inhibited steel surface supported the adsorption of the corrosion inhibitor on the metallic surface.