Current Nanoscience - Volume 17, Issue 5, 2021

Nature mimicry rather, biomimicry is one such field being considered for the backbone of the most astounding inventions in recent science and technology. Biomimicry combined with nanotechnology developed many sustainable solutions to satisfy problems existing in daily life. In this article, we explore the individual concepts of biomimicry and nano-technology and then the combination of the both. The current review mainly focusses on nano innovations inspired by lotus leaf, gecko feet, butterfly wings, shark skin and peacock spider. We then look at the biological structures (more in nano-dimensions) from the entrenched interference patterns found on the butterfly wings inspiring in the development of display technologies to the self-cleaning properties of lotus that has resulted in the synthesis of nano materials having self-cleaning properties. In addition, insects like spiders which have inspired the most important inventions like optical devices, sensors, are also investigated. The challenges faced while implementing the biomimetic approach into technology are explained. We have also tried to shed light on the solutions which can tackle these challenges and issues.

Background: Nanopopcorns are a novel class of metallic nanoparticles that demonstrate structural similarity to the grains of popcorns with theranostic activities for diseases like cancer and bacterial infection using Surface Enhanced Raman Spectroscopy-based detection.

Objective: The objective of the present article is to highlight the importance of popcorn-shaped nanoparticles for the treatment of various disease conditions like cancer, diabetes, ulcerative colitis, rheumatoid arthritis, etc.

Methods: Nanopopcorns enter the target cells via conjugation with various proteins, aptamers, etc. to kill the diseased cell. Moreover, external magnetic radiations are provided to heat these metallic nanopopcorns for creating hotspots. All such activities can be tracked via SERS mechanism.

Results: Nanopopcorns create alternative and minimally-invasive treatment strategies for inflammatory conditions and life-threatening diseases.

Conclusion: In the near future, nanopopcorn-based drug delivery system can be an interesting field for research in medicinal nanotechnology.

Sensing devices own a vital role in supporting medical needs for the early recognition and diagnosis of diseases. In the past half-century, researchers have developed many biosensors for suitable applications, but only a limited number of biosensors are commercially available. The biosensors are biological recognition devices with high target specificity and high sensitivity leading to commercialization and wider acceptability in the existing market of health care industries. The nanosized materials are indispensable in the biomedical field because of their captivating characteristics like increased surface area and novel quantum effects. Nanoscale materials are very closer to biological molecules in size and own good specificity when used in biosensors. An overview of the working principles of various commonly used biosensors will be presented and a special emphasis is given to graphene-based biosensors to monitor the interaction of biological molecules. Graphene is one of the most superior nanocomposite that provides an opportunity for the best sensing platform in the field of bioanalysis. The supremacy of Graphene and GFET devices in biosensors for analyzing the biological samples and to provide consistent data is investigated using a simulation tool. Meanwhile, the performance behavior of nano-biosensors based on their dimensional influence is also explored. This review may provide constructive guidance for examining the interfacial interaction between nano composites and tiny biological components to impart knowledge or regulate things based on the application chosen.

Nanofluids, which consist of base liquid and nano-sized conductive particles, are widely acclaimed as a new generation liquid for heat transfer applications. Since they possess a variety of conductive particles, they can be efficiently utilized in a heat exchanger. These nano-sized conductive particles can increase the surface area, thus the heat transfer area, changing their thermophysical features. Density, thermal conductivity, viscosity, and heat capacity are crucial parameters and cannot be underestimated in heat transfer. These properties can be manipulated by the particle and baseliquid and can significantly influence the performance of nanofluids. In the last decade, several models, equations, and investigations have been performed to examine the parameters that promote these properties. A review is necessary to locate terms for classifying studies that are both compatible and contradictory to the effects of density, thermal conductivity, viscosity, and heat capacity on the performance of nanofluids.

Background: The hydrogen evolution reaction is a crucial step in electrochemical water splitting to generate molecular hydrogen with high purity, but it usually suffers from a sluggish reaction kinetics in alkaline media because of additional water dissociation and/or improper adsorption energy of reactive hydrogen intermediates. It is desirable to design highly active and robust nonprecious electrocatalysts as alternatives to state-of-the-art commercially available Pt/C catalysts for large-scale hydrogen production via water-alkali electrolysis. Methods: We developed monolithic nanoporous hybrid electrodes composed of electroactive Mo@MoOx nanoparticles, which are seamlessly integrated on hierarchical nanoporous Cu scaffold (Cu/Mo@MoOx) by making use of a spontaneous phase separation of Mo nanoparticles and subsequently, self-grown MoOx in chemical dealloying. Results: Owing to the unique monolithic electrode architecture, in which the constituent Mo@MoOx nanoparticles work as electroactive sites and the hierarchical nanoporous Cu skeleton serves as fast electron-transfer and mass-transport pathways, the monolithic nanoporous Cu/Mo@MoOx hybrid electrode exhibits superior electrocatalysis in 1 M KOH, with a low Tafel slope of 66 mV dec⁻¹ and outstanding stability. It only takes them ~185 mV overpotential to reach −400 mA cm⁻², ~150 mV lower than that of nanoporous Cu supported Pt/C. Conclusion: The outstanding electrochemical performance and excellent structural stability make nanoporous Cu/Mo@MoOx electrodes attractive alternatives to Pt/C catalysts in alkaline-based devices.

Background: Ondansetron and paracetamol are often co-administrated to prevent and treat nausea and vomiting caused by anaesthesia and to control postoperative pain. In addition, ondansetron is used as the first-line antiemetic in paracetamol overdose. Therefore, a selective and sensitive method for their simultaneous analysis is of great importance. The electroanalytical methods are highly sensitive and offer many possibilities for new sensor platform design. However, at present, no electroanalytical method for simultaneous determination of these drugs has been proposed. Objective: The aim of this study was to develop a novel nanosensor for selective monitoring of ondansetron and paracetamol in pharmaceutical and biological samples without expensive and timeconsuming pretreatments. Methods: The graphitized multi-walled carbon nanotubes embedded in a cation exchange polymer matrix were selected, among various surface functionalizations evaluated, to design a novel sensor. Based on its excellent sensing performance, the first electroanalytical method was developed for the rapid concurrent determination of investigated drugs. Results: The scanning electron microscopy study showed an interlinked nanoporous network structure and a highly enlarged active surface. The developed sensor facilitated electron transfer in the oxidation of both drugs and tremendously enhanced the adsorption capacity for ondansetron, thus exhibiting a significant increase in drug responses and sensitivity. To obtain much sensitive response of investigated drugs, the effect of pH values of supporting electrolyte, dispersed nanomaterial amount, the cation exchange polymer concentration, drop-casting volume of nanocomposite suspension, accumulation potential and deposition time on the peak current was evaluated. The developed electroanalytical method was validated and the practical utility of the proposed nanosensor was tested. Conclusion: The developed sensor is a promising sensing platform with a fast response time for analysis of ondansetron and paracetamol at very different concentration levels found in their fixeddose combination and human serum sample after recommended daily doses showing its potential usage in pharmaceutical quality control and clinical research.

Background: Drug loaded β-cyclodextrin based nanosponges (CDNS) are of special interest for the entrapment of moieties with the view to address their physicochemical challenges, and to improve their delivery characteristics and utility. Dithranol (DTH), the standard drug for psoriasis, has poor stability and solubility, which limit its pharmaceutical applications. Objective: The objective of the current study was to entrap DTH in CDNS in order to alleviate the above-mentioned challenges. Methods: To synthesize CDNS, β-cyclodextrin was treated with diphenyl carbonate in various molar ratios. The obtained placebo CDNS were loaded with DTH by lyophilisation. The particle size of the DTH loaded CDNS was found to lie between 150 and 450 nm, with a narrow polydispersity index range. Fourier transform infrared spectroscopy, thermal analysis, X-ray diffraction, zeta potential and electron microscopy with energy dispersive spectroscopy (EDS) were conducted for characterization of DTH-CDNS. Results: Findings from spectral examinations confirmed the formation of inclusion complexes. Solubilisation efficiency of DTH (in distilled water) was found augmented 4.54 folds with optimized CDNS. The cytocompatibility study was performed by the MTT assay employing THP1 cell lines. A remarkable amelioration in stability and photostability of DTH was also observed by its inclusion in nanosponges. Conclusion: In a nutshell, we report the rational engineering and characterization of DTH loaded cyclodextrin-based nanosponges, and subsequently, their stepwise screening for photostability, in vitro release, in vitro cytocompatibility, in vitro antioxidant and in vitro inflammatory activity in a top-down manner, yielding the best carrier for this drug.

Background: The feasibility of plant extracts for metallic nanoparticle fabrication has been demonstrated. Each plant species impacts differently on formed nanoparticles, thus specific plants need to be explored in detail. Objective: Continuing the fabrication of nanoparticles using green method, Garcinia mangostana shell and Tradescantia spathacea leaf extract are exploited as reducing sources to form two types of silver nanoparticles (GMS-AgNPs and TSL-AgNPs) less than 50 nm. Methods: Structural characterization of GMS-AgNPs and TSL-AgNPs was performed by ultravioletvisible spectrophotometry (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray energy dispersive spectrometer (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Antifungal tests of GMS-AgNPs and TSL-AgNPs were performed with Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum. Results: UV-vis spectra with the 440-nm peak demonstrate the silver nanoparticle formation. FTIR analysis shows the GMS-AgNPs and TSL-AgNPs modified by organic functional groups. The SEM and TEM images indicate that the GMS-AgNPs are spherical shaped with rough edged, while the TSL-AgNPs are spherical shape with smooth surface. The GMS-AgNP average size (15.8 nm) is smaller than TSL-AgNP (22.4 nm). In addition, antifungal tests using Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum reveal that GMS-AgNPs and TSL-AgNPs can significantly inhibit the proliferation of these fungal strains. Conclusion: Garcinia mangostana shell and Tradescantia spathacea leaf extract as renewable and eco-friendly resources playing a dual role for nanoparticle biosynthesis create GMS-AgNPs and TSL-AgNPs with high antifungal efficiency for biomedical or agricultural applications.

Background: The root extracts of Asparagus racemosus (shatamuli) have been used as a benign reducing agent to reduce graphene oxide (GO) and reduced graphene oxide (rGO). The root extract, that is used as a green, reducing agent, is non-toxic, eco-friendly, and naturally therapeutic. Methods: The formation of rGO was identified using XRD, FTIR, TEM, and EDX techniques. Results: The DLS and Zeta potential data revealed that the hydrodynamic size of this rGO is lower than 200 nm with optimal charge. Conclusion: These results may be useful for the use of GO as a probe in biomedical research.

Background: Pancreatic cancer leaves little hope for survival among patients. This is due to its cancerous cell resistance to radiation and chemicals. Objective: Synergistic effect between three modalities of pancreatic cancer treatment is investigated. These are radiation therapy, hyperthermia and graphene oxide nanosheets. The aim is to overcome resistance of pancreatic cancer cells against radiation therapy. Methods: Cancerous cell lines were treated by each one of three modalities separately. Other samples were treated with various combinations of these modalities. Hyperthermia was accomplished by placing cell lines for 15 min in 42°C. In the course of radiation therapy, the cancerous cells were irradiated by 6 MV Linac for two cases of 2 Gy and 3 Gy. The cell line viability was readout by MTT assay 24 hours and 48 hours after treatment. Results: In single modality treatment it was shown that 24h after the treatment, the group treated by RT 3 Gy had the highest cell killing result. Following up the result in 48h readout, hyperthermia and 3 Gy radiotherapy had similar results. In double modality treatment, for both 24h and 48h viability readout, the group graphene-oxide plus 2 Gy radiotherapy showed cell survival amounting to 69% and 43%, respectively being the lowest cell survival among all double combinations. Conclusion: In triple modality treatment, the cell viability for 24h showed no significant improvement but in 48h, the hyperthermia plus Graphene-oxide and 3 Gy radiotherapy had very low cell viability. Significant sensitizing effect for GO, when combined with radiation therapy, was observed.

Background: Post-arthroplasty implant-related infection is one of the most feared complications with adverse consequences for patients and public health systems, especially in terms of the huge financial cost of treatment. This is compounded by the potential risks of continuous metamorphosis and emergence of new resistant bacterial strains. Constructing an antibacterial surface, therefore, on the implant represents an approach to reduce the incidence of implant-related infections. Methods: In this study, a covalent-driven layer-by-layer self-assembly of clindamycin-loaded polyethylene glycol grafted polylactic acid nanoparticles/chitosan membrane has been successfully fabricated on the titanium sheet and evaluated for drug releasing potential and antibiotic activity. Results: Attenuated total reflectance spectrum of the layer-by-layer self-assembly membrane showed three absorption peaks around 1680, 1520 and 1240 cm^-1, which are the characteristic absorption peaks of secondary amines. The results indicated the formation of an amide bond between the carboxyl groups of clindamycin-loaded polyethylene glycol grafted polylactic acid nanoparticles and the amino groups of chitosan. The covalent bond stabilized the membrane construct. The membrane exhibited a sustained drug release behavior whereby less than 50% of clindamycin was released after 160 hr. The membrane persistently inhibited the growth of Staphylococcus aureus with the inhibition ratio exceeding 60%. Conclusion: The membrane construct holds a great potential for managing anti-implant-related infections.