Photoluminescence of ZnO Nanowires: A Review

One-dimensional ZnO nanostructures (nanowires/nanorods) are attractive materials for applications such as gas sensors, biosensors, solar cells, and photocatalysts. This is due to the relatively easy production process of these kinds of nanostructures with excellent charge carrier transport properties and high crystalline quality. In this work, we review the photoluminescence (PL) properties of single and collective ZnO nanowires and nanorods. As different growth techniques were obtained for the presented samples, a brief review of two popular growth methods, vapor-liquid-solid (VLS) and hydrothermal, is shown. Then, a discussion of the emission process and characteristics of the near-band edge excitonic emission (NBE) and deep-level emission (DLE) bands is presented. Their respective contribution to the total emission of the nanostructure is discussed using the spatial information distribution obtained by scanning transmission electron microscopy−cathodoluminescence (STEM-CL) measurements. Also, the influence of surface effects on the photoluminescence of ZnO nanowires, as well as the temperature dependence, is briefly discussed for both ultraviolet and visible emissions. Finally, we present a discussion of the size reduction effects of the two main photoluminescent bands of ZnO. For a wide emission (near ultra-violet and visible), which has sometimes been attributed to different origins, we present a summary of the different native point defects or trap centers in ZnO as a cause for the different deep-level emission bands

ZnO Nanowires/N719 dye with different aspect ratio as a possible photoelectrode for Dye-Sensitized Solar Cells

The vapor-liquid-solid (VLS) process was applied to fabricate zinc oxide nanowires (ZnO NWs) with a different aspect ratio (AR), morphological, and optical properties. The ZnO NWs were grown on a system that contains a quartz substrate with transparent conductive oxide (TCO) thin film followed by an Al-doped ZnO (AZO) seed layer; both films were grown by magnetron sputtering at room temperature. It was found that the ZnO NWs presented high crystalline quality and vertical orientation from different structural and morphological characterizations. Also, NWs showed a good density distribution of 69 NWs/μm2 with a different AR that offers their capability to be used as possible photoelectrode (anode) in potential future device applications. The samples optical properties were studied using various techniques such as photoluminescence (PL), absorption, and transmittance before and after sensitization with N719 dye. The results demonstrated that NW with 30 nm diameter had the best characteristics as feasible photoelectrode (anode) (high absorption, minimum recombination, high crystallinity). Also, the present samples optical properties were found to be improved due to the existence of N719 dye and Au nanoparticles on the tip of NWs. NWs grown in this work can be used in different photonic and optoelectronic applications

Zinc associated nanomaterials and their intervention in emerging respiratory viruses: Journey to the field of biomedicine and biomaterials.

Respiratory viruses represent a severe public health risk worldwide, and the research contribution to tackle the current pandemic caused by the SARS-CoV-2 is one of the main targets among the scientific community. In this regard, experts from different fields have gathered to confront this catastrophic pandemic. This review illustrates how nanotechnology intervention could be valuable in solving this difficult situation, and the state of the art of Zn-based nanostructures are discussed in detail. For virus detection, learning from the experience of other respiratory viruses such as influenza, the potential use of Zn nanomaterials as suitable sensing platforms to recognize the S1 spike protein in SARS-CoV-2 are shown. Furthermore, a discussion about the antiviral mechanisms reported for ZnO nanostructures is included, which can help develop surface disinfectants and protective coatings. At the same time, the properties of Zn-based materials as supplements for reducing viral activity and the recovery of infected patients are illustrated. Within the scope of noble adjuvants to improve the immune response, the ZnO NPs properties as immunomodulators are explained, and potential prototypes of nanoengineered particles with metallic cations (like Zn2+) are suggested. Therefore, using Zn-associated nanomaterials from detection to disinfection, supplementation, and immunomodulation opens a wide area of opportunities to combat these emerging respiratory viruses. Finally, the attractive properties of these nanomaterials can be extrapolated to new clinical challenges

Zinc associated nanomaterials and their intervention in emerging respiratory viruses:Journey to the field of biomedicine and biomaterials

Respiratory viruses represent a severe public health risk worldwide, and the research contribution to tackle the current pandemic caused by the SARS-CoV-2 is one of the main targets among the scientific community. In this regard, experts from different fields have gathered to confront this catastrophic pandemic. This review illustrates how nanotechnology intervention could be valuable in solving this difficult situation, and the state of the art of Zn-based nanostructures are discussed in detail. For virus detection, learning from the experience of other respiratory viruses such as influenza, the potential use of Zn nanomaterials as suitable sensing platforms to recognize the S1 spike protein in SARS-CoV-2 are shown. Furthermore, a discussion about the antiviral mechanisms reported for ZnO nanostructures is included, which can help develop surface disinfectants and protective coatings. At the same time, the properties of Zn-based materials as supplements for reducing viral activity and the recovery of infected patients are illustrated. Within the scope of noble adjuvants to improve the immune response, the ZnO NPs properties as immunomodulators are explained, and potential prototypes of nanoengineered particles with metallic cations (like Zn(2+)) are suggested. Therefore, using Zn-associated nanomaterials from detection to disinfection, supplementation, and immunomodulation opens a wide area of opportunities to combat these emerging respiratory viruses. Finally, the attractive properties of these nanomaterials can be extrapolated to new clinical challenges

Anticipating Challenges in Optical Nanobiosensors for Global Detection of Respiratory Viruses and Emerging Threats

The unprecedented SARS-CoV-2 pandemic has opened huge opportunities for nanomaterial-based biosensors focused on timely detection of emerging respiratory viruses, where challenges must address actions for fast response and massive application. Accordingly, we provide a comprehensive perspective on critical aspects, including nanomaterials, biofunctionalization strategies, and bioreceptors engineering to increase accuracy, emphasizing optical nanobiosensors. The first biosensing prototype performance reveals the need to consider crucial factors for improvement, such as handling detection in complex matrices, standardization for commercial purposes, portability, integration with artificial intelligence, sustainability, and economic feasibility. By achieving these goals, biosensors would foster a prepared global healthcare landscape

Interaction Study of Anti‐E. coli Immobilization on 1DZnO at Nanoscale for Optical Biosensing Application

Abstract Developing low‐cost biosensing platforms for robust detection response and sensitivity at low concentrations is of great interest. This work reports synthesizing 1D ZnO nanostructured materials (1DZnO) with controllable properties utilizing a metal catalyst‐assisted vapor phase growth technique (VLS). The obtained materials are functionalized with (3‐aminopropyl) trimetoxysilane (APTMS) and immobilized with anti‐Escherichia coli enteropathogenic (EPEC) antibodies. Characterization results show changes in the optical and structural properties of 1DZnO that are correlated with the biofunctionalization methodologies. Further, the biofunctionalization process is assessed on 1DZnO surface platforms to obtain acceptable antibody immobilization efficiencies (52%, 96%, and 100%) using a low‐concentration antibody solution (30 µg ml−1). Special techniques such as focused ion beam micromachining and scanning tunneling electron microscopy are proposed to appreciate the semiconductor biofunctionalization layer around 1DZnO and explain the physics of the interaction process. It is found that morphology obtained from distinct synthesis methods, solvents, and functionalization agents can generate functional groups for biomolecule attachment. Remarkably, it is demonstrated that biofunctionalization on 1DZnO takes place all over a single nanostructure. This work presents a proof‐of‐concept focused on generating pathogen sensing platforms using 1DznO semiconducting materials, providing new insights into bio‐analytes interaction with structures at the nanoscale

Catalyzing innovation:Exploring iron oxide nanoparticles - Origins, advancements, and future application horizons

Iron oxides, including wustite (FeO), hematite (α-Fe2O3), maghemite (γ-Fe2O3), and magnetite (Fe3O4), are remarkable nanomaterials. Iron oxide nanoparticles (IONPs) at the nanoscale display super-paramagnetic, high surface area, and biocompatibility, making them ideal for diverse applications. Their influence on matter behavior, interaction with light, electricity, magnetism, and non-toxicity in biological systems make them promise in biomedicine. This review covers IONPs' properties, emphasizing biological, chemical, and physical synthesis methods, including doping, coating, and encapsulation. In addition, advancing green synthesis approaches for IONPs are highlighted. We explore their applications in medicine, environmental science, and pollution solutions, emphasizing their merits. Examining various IONPs and synthesis routes, we underscore their role in addressing global challenges. IONPs versatility, scalability, and eco-friendliness position them to transform research and uphold ethical standards. This review unveils the transformative potential of Iron Oxide Nanoparticles (IONPs), emphasizing their unique attributes—biocompatibility, magnetic responsiveness, and tunable surface functionalities. IONPs are pivotal in targeted drug delivery, imaging, hyperthermia therapy, and biosensing. The comprehensive exploration spans biomedical, agricultural, antioxidant, and photocatalytic applications, showcasing IONPs versatility in advancing innovative solutions across diverse domains. Our collective efforts aim to revolutionize medical treatments, combat environmental issues, and foster a sustainable future while advocating responsible research and ethics.</p

Optical Detection of Cancer Cells Using Lab-on-a-Chip

The global need for accurate and efficient cancer cell detection in biomedicine and clinical diagnosis has driven extensive research and technological development in the field. Precision, high-throughput, non-invasive separation, detection, and classification of individual cells are critical requirements for successful technology. Lab-on-a-chip devices offer enormous potential for solving biological and medical problems and have become a priority research area for microanalysis and manipulating cells. This paper reviews recent developments in the detection of cancer cells using the microfluidics-based lab-on-a-chip method, focusing on describing and explaining techniques that use optical phenomena and a plethora of probes for sensing, amplification, and immobilization. The paper describes how optics are applied in each experimental method, highlighting their advantages and disadvantages. The discussion includes a summary of current challenges and prospects for cancer diagnosis