Molecular Plasmonic Silver Forests for the Photocatalytic-Driven Sensing Platforms

Structural electronics, as well as flexible and wearable devices are applications that are possible by merging polymers with metal nanoparticles. However, using conventional technologies, it is challenging to fabricate plasmonic structures that remain flexible. We developed three-dimensional (3D) plasmonic nanostructures/polymer sensors via single-step laser processing and further functionalization with 4-nitrobenzenethiol (4-NBT) as a molecular probe. These sensors allow ultrasensitive detection with surface-enhanced Raman spectroscopy (SERS). We tracked the 4-NBT plasmonic enhancement and changes in its vibrational spectrum under the chemical environment perturbations. As a model system, we investigated the sensor’s performance when exposed to prostate cancer cells’ media over 7 days showing the possibility of identifying the cell death reflected in the environment through the effects on the 4-NBT probe. Thus, the fabricated sensor could have an impact on the monitoring of the cancer treatment process. Moreover, the laser-driven nanoparticles/polymer intermixing resulted in a free-form electrically conductive composite that withstands over 1000 bending cycles without losing electrical properties. Our results bridge the gap between plasmonic sensing with SERS and flexible electronics in a scalable, energy-efficient, inexpensive, and environmentally friendly way.</p

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

Selected Papers from the 1st International Electronic Conference on Biosensors (IECB 2020)

The scope of this Special Issue is to collect some of the contributions to the First International Electronic Conference on Biosensors, which was held to bring together well-known experts currently working in biosensor technologies from around the globe, and to provide an online forum for presenting and discussing new results. The world of biosensors is definitively a versatile and universally applicable one, as demonstrated by the wide range of topics which were addressed at the Conference, such as: bioengineered and biomimetic receptors; microfluidics for biosensing; biosensors for emergency situations; nanotechnologies and nanomaterials for biosensors; intra- and extracellular biosensing; and advanced applications in clinical, environmental, food safety, and cultural heritage fields

The 2nd International Electronic Conference on Applied Sciences

This book is focused on the works presented at the 2nd International Electronic Conference on Applied Sciences, organized by Applied Sciences from 15 to 31 October 2021 on the MDPI Sciforum platform. Two decades have passed since the start of the 21st century. The development of sciences and technologies is growing ever faster today than in the previous century. The field of science is expanding, and the structure of science is becoming ever richer. Because of this expansion and fine structure growth, researchers may lose themselves in the deep forest of the ever-increasing frontiers and sub-fields being created. This international conference on the Applied Sciences was started to help scientists conduct their own research into the growth of these frontiers by breaking down barriers and connecting the many sub-fields to cut through this vast forest. These functions will allow researchers to see these frontiers and their surrounding (or quite distant) fields and sub-fields, and give them the opportunity to incubate and develop their knowledge even further with the aid of this multi-dimensional network

Investigation of Volatile Organic Compounds (VOCs) released as a result of spoilage in whole broccoli, carrots, onions and potatoes with HS-SPME and GC-MS

Vegetable spoilage renders a product undesirable due to changes in sensory characteristics. The aim of this study was to investigate the change in the fingerprint of VOC composition that occur as a result of spoilage in broccoli, carrots, onions and potatoes. SPME and GC-MS techniques were used to identify and determine the relative abundance of VOC associated with both fresh and spoilt vegetables. Although a number of similar compounds were detected in varying quantities in the headspace of fresh and spoilt samples, certain compounds which were detected in the headspace of spoilt vegetables were however absent in fresh samples. Analysis of the headspace of fresh vegetables indicated the presence of a variety of alkanes, alkenes and terpenes. Among VOCs identified in the spoilt samples were dimethyl disulphide and dimethyl sulphide in broccoli; Ethyl propanoate and Butyl acetate in carrots; 1-Propanethioland 2-Hexyl-5-methyl-3(2H)-furanone in onions; and 2, 3-Butanediol in potatoes. The overall results of this study indicate the presence of VOCs that can serve as potential biomarkers for early detection of quality deterioration and in turn enhance operational and quality control decisions in the vegetable industry

A Novel Sensing Methodology to Detect Furfural in Water, Exploiting MIPs, and Inkjet-Printed Optical Waveguides

A novel optical platform has been used to monitor the interaction between a molecularly imprinted polymer (MIP) and a small molecule. The new optical sensor is made of a polyethylene terephthalate substrate with a pattern of silver nanoparticles, printed on it by inkjet technology, and two plastic optical fibers (POFs). The POFs connect the optical sensor, later covered by the MIP layer, with a light source and with a spectrometer. The detection of furfural (furan-2-carbaldehyde, 2-FAL) in aqueous media was investigated exploiting a selective MIP receptor. The experimental results show that this novel approach presents a limit of detection of about 0.03 ppm, comparable to that of plasmonic sensors combined with the same MIP, but with the advantage of an easier preparation procedure

A Novel Sensing Methodology to Detect Furfural in Water, Exploiting MIPs, and Inkjet-Printed Optical Waveguides

A novel optical 1 platform has been used to monitor 2 the interaction between a molecularly imprinted polymer (MIP) 3 and a small molecule. The new optical sensor is made of a 4 polyethylene terephthalate substrate with a pattern of silver 5 nanoparticles, printed on it by inkjet technology, and two plastic 6 optical fibers (POFs). The POFs connect the optical sensor, 7 later covered by the MIP layer, with a light source and with 8 a spectrometer. The detection of furfural (furan-2-carbaldehyde, 9 2-FAL) in aqueous media was investigated exploiting a selective 10 MIP receptor. The experimental results show that this novel 11 approach presents a limit of detection of about 0.03 ppm, 12 comparable to that of plasmonic sensors combined with the same 13 MIP, but with the advantage of an easier preparation procedure