Two-dimensional nanostructures based '-onics' and '-omics' in personalized medicine

With the maturing techniques for advanced synthesis and engineering of two-dimensional (2D) materials, its nanocomposites, hybrid nanostructures, alloys, and heterostructures, researchers have been able to create materials with improved as well as novel functionalities. One of the major applications that have been taking advantage of these materials with unique properties is biomedical devices, which currently prefer to be decentralized and highly personalized with good precision. The unique properties of these materials, such as high surface to volume ratio, a large number of active sites, tunable bandgap, nonlinear optical properties, and high carrier mobility is a boon to 'onics' (photonics/electronics) and 'omics' (genomics/exposomics) technologies for developing personalized, low-cost, feasible, decentralized, and highly accurate medical devices. This review aims to unfold the developments in point-of-care technology, the application of 'onics' and 'omics' in point-of-care medicine, and the part of two-dimensional materials. We have discussed the prospects of photonic devices based on 2D materials in personalized medicine and briefly discussed electronic devices for the same. © 2022 the author(s), published by De Gruyter, Berlin/Boston.Instrumental Analysis Centre of Shenzhen UniversityMacao Special Administration RegionShenzhenKQTD2015032416270385, (JCYJ20150625103619275, JCYJ20170811093453105)Songshan Lake Materials LaboratoryNational Natural Science Foundation of China, NSFC, (61435010, 6181101252, 61875138)Science and Technology Development Fund, STDF, (007/2017/A1, 132/2017/A3)Department of Education of Guangdong Province, DEGP, (2018KCXTD026)Science, Technology and Innovation Commission of Shenzhen MunicipalityThe authors extend sincere thanks to the funding and support from Aaivalayam, India. One of the authors Manavalan Rajesh Kumar convey his thanks to the contract no. 40/is2

Surface plasmon resonance sensing: an optical fibre based SPR platform with scattered light interrogation

This thesis describes the development, fabrication and optimisation of a Surface Plasmon Resonance (SPR) sensing architecture based on optical fibres. Motivated by biosensing applications, SPR was chosen as a simple and sensitive label-free technique that allows real time quantitative measurements of biomolecular interactions. Unlike conventional fibre SPR probes, this platform utilises a novel interrogation mechanism based on the analysis of scattered radiation facilitated by a rough plasmonic coating. A theoretical study is performed in order to determine the optimal parameters of the sensing configuration, i. e. the metal coating and fibre material. This analysis revealed a trade-off between the sensitivity of these devices, and their resolution. Optical fibres with cores made of lower refractive index materials were found to increase the sensitivity of the sensor, but broaden the SPR spectral signature. This broadening of the linewidth results in an unwanted increase in the sensor resolution, which leads to an undesirable increase in the detection limit. Therefore, experiments were performed to investigate the trade off between the sensitivity and resolution of the sensor to optimise both performance characteristics. The experimental demonstration and characterisation of a scattering SPR platform based on lead silicate fibres is described. The plasmonic coating with required surface roughness was fabricated using chemical electroless plating. In order to increase the refractive index sensitivity, a fibre SPR sensor with a lower refractive index core made of fused silica was produced. Due to the different surface properties of the silica glass and the lead silicate glass, surface modification with stannous chloride was required to fabricate suitable plasmonic coatings on the fused silica fibres. Characterisation of the new fused silica SPR sensors showed that the sensitivity of the sensing probe was improved, however, the spectral linewidth of the SPR signature was broadened, in agreement with the theoretical modelling. Nevertheless, analysis of the capability of the silica fibre based SPR sensors demonstrated potential for this platform in biological studies. To improve the resolution without affecting the sensitivity of a sensor, smaller core fibres can be used. However, using conventional small core fibres or fibre tapers is challenging due to their fragility and the requirement for fibre post processing to access the core. To overcome these difficulties, an SPR sensor based on a silica microstructured optical fibre with a core exposed along the entire fibre length was fabricated. Exposed Core Fibres (ECFs) have small cores that are supported by thin struts inside of a larger support structure, providing mechanical robustness to the fibre. The ECF SPR sensing platform doubled the improvement in the spectral linewidth when compared to the large core fused silica fibre sensor, without compromising sensitivity. Finally, the demonstration of Metal Enhanced Fluorescence (MEF) phenomena is presented. The effect of rough metallic coatings on the enhancement of fluorescence emission is investigated in planar glass substrates, showing significant improvement in emission when compared to smooth metal films. An optical fibre based MEF platform was demonstrated to illustrate the potential of rough metal coatings on a fibre for surface enhanced optical phenomena. This work is the first systematic study of a scattering based SPR sensing platform. This architecture addresses existing practical limitations associated with current SPR technologies, including but not limited to bulk design and affordability. Additionally, performance enhancement of the sensing probes is achieved through the use of alternative fibre material and geometry. The demonstrated performance improvements are not class-leading compared to commercial biosensing devices, however, the performance is in agreement with the theoretical analysis which provides a pathway for further improvement. This demonstrated that the scattering based SPR fibre platform is a practical new approach that offers the advantages of high sensitivity and signal to noise ratio, and low resolution, with the capability to improve the detection limit of SPR devices. Most importantly, this novel SPR interrogation approach allows the incorporation of two different sensing techniques, SPR and fluorescence, in the same fibre device, which opens pathways for novel biosensing applications combining the two phenomena.Thesis (Ph.D.)--University of Adelaide, School of Physical Sciences, 2017

Sensores em POF baseados em intensidade para a avaliação da qualidade de águas

Nowadays there is the need for low-cost and user-friendly solutions for water quality assessment which can allow for remote, in-site and real-time monitoring of water contaminants. POF sensing technologies combined with specially developed sensitive layers for chemical detection may offer these possibilities, with proper interrogation systems. POF sensing platforms based on low-cost procedures were developed and characterized using aqueous solutions of different refractive indices (RI). The POF RI sensors were optimized by varying the length and/or roughness of the sensing region. The suitability of these sensing platforms for chemical detection was evaluated through the coating with sensitive layers, namely molecularly imprinted polymers (MIPs) using different deposition techniques. The dependency of proteins immobilization on the POF’s surface was evaluated aiming future developments in chemical detection using POF biosensors. A D-shaped POF chemical sensor was successfully developed using a sensitive MIP layer, allowing the detection of perfluorooctanoate (POFA/PFO-) in aqueous media with a limit of detection of 0.20 – 0.28 ppb. The collaboration of researchers from different areas was essential for the success of the developed work.Hoje em dia há uma necessidade de soluções simples e de baixo custo para a avaliação da qualidade de águas e que permitam a monitorização remota de contaminantes, no local e em tempo real. As tecnologias baseadas em POF podem oferecer essa possibilidade através de sistemas de interrogação óptica adequados, combinados com camadas sensíveis especialmente desenvolvidas para detecção química. As plataformas ópticas baseadas em POF foram desenvolvidas e caracterizadas com soluções aquosas com diferentes índices de refracção. Os sensores foram optimizados através da variação do comprimento e/ou rugosidade da região sensível. A capacidade de detecção química das plataformas ópticas desenvolvidas foi avaliada através do revestimento com camadas sensíveis, nomeadamente polímeros molecularmente impressos (PMI), utilizando diferentes técnicas de deposição. A dependência da imobilização de proteínas na superfície de POFs modificadas foi avaliada com o objectivo de desenvolver biossensores para detecção química. Um sensor POF para detecção química, em configuração D-shape, foi desenvolvido com sucesso através do revestimento com um PMI, permitindo a detecção de perfluorooctanoato (POFA/PFO-) em soluções aquosas com um limite de detecção entre 0.20 – 0.28 ppb. A colaboração com investigadores de diferentes áreas foi essencial para o sucesso do trabalho desenvolvido.Programa Doutoral em Engenharia Físic

Sistemas híbridos basados en grafeno y MoS2-2D para detección óptica

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de Materiales. Fecha de Lectura: 02-12-202