Osvaldo N Oliveira

University of São Paulo | USP · Institute of Physics São Carlos (IFSC)

An electronic tongue was developed for the detection of lactose content in commercial foods. This was accomplished by employing optimized detection units comprised of gelatin films and information visualization methods for data analysis. The films incorporating gelatin, tannic acid, and zein, served as the basis for the sensors, whose electrodes we...

Upconverting nanoparticles are essential in modern photonics due to their ability to convert infrared light to visible light. Despite their significance, they exhibit limited brightness, a key drawback that can be addressed by combining them with plasmonic nanoparticles. Plasmon-enhanced upconversion has been widely demonstrated in dry environments...

Sticky-colored labels are an efficient way to communicate visual information. However, most labels are static. Here, we propose a new category of dynamic sticky labels that change structural colors when stretched. The sticky mechanochro-mic labels can be pasted on flexible surfaces such as fabric and rubber or even on brittle materials. To enhance...

Having a direct or indirect band gap can influence the potential applications of a semiconductor, for indirect band gap materials are usually not suitable for optoelectronic devices. Even though this is a fundamental property of semiconducting materials, discussed in textbooks, no unified theory exists to explain why a material has a direct or indi...

In this work, we combine the concepts of magnetic circular dichroism, nanocavities and magneto-optical hyperbolic metamaterials (MO-HMM) to demonstrate an approach for sensing down to few molecules. Our proposal comprises a multilayer MO-HMM with a square two-dimensional arrangement of nanocavities. The magnetization of the system is considered in...

The selective, rapid detection of low levels of hormones in drinking water and foodstuffs requires materials suitable for inexpensive sensing platforms. We report on core–shell Ag@C nanocables (NCs) decorated with carbon spherical shells (CSSs) and silver nanoparticles (AgNPs) by using a hydrothermal green approach. Sensors were fabricated with hom...

Changes in pH affect metabolic pathways, primarily by modulating enzyme conformations, which is why a detailed analysis of pH-driven conformational transitions is required to understand the underlying biochemistry of diseases and biological organisms. In this work, we examined the pH-driven conformational dynamics of Bovine Serum Albumin (BSA), wit...

Contamination of waters by acetaminophen (paracetamol), one of the most consumed non-opioid analgesics, is a cause of public concern owing to inadequate disposal and inefficient water treatment. In this paper, we report on a photoelectrochemical (PEC) sensor made with screen-printed carbon electrodes (SPCEs) modified with carbon spherical shells (C...

The use of electrical impedance spectroscopy in point-of-care systems or for on-line monitoring has been hampered by the high cost of typical benchtop impedance analyzers. In this paper we introduce a portable, low-cost impedance analyzer, referred to as ‘Simple-Z’, which contains a signal processing unit that allows for a precise generation and re...

Upconverting nanoparticles have been used as optical probes in a great variety of scenarios ranging from cells to animal model. A single upconverting nanoparticles can be remotely manipulated by laser in a contactless way. When assessing an optically trapped single nanoparticle, the luminescence intensity and the trapping stability is very limited....

The deployment of fifth-generation mobile network (5G), beyond 5G (B5G) and sixth-generation mobile network (6G) platforms encounters challenges of blockage, interference, and path-loss in radio mobile environments. Metasurfaces provide a promising solution to address these limitations. In this paper, we present a methodology for developing ultra-t...

Recent progress in natural language processing (NLP) enables mining the literature in various tasks akin to knowledge discovery. Obtaining an updated birds-eye view of key research topics and their evolution in a vast, dynamic field such as materials science is challenging even for experienced researchers. In this Perspective paper, we present a la...

Wearable sensors such as those made with paper are needed for non-destructive routine analysis of pesticides on plants, fruits, and vegetables. Herein we report on electrochemical sensors made with screen-printed carbon electrodes on kraft and parchment papers to detect the fungicide carbendazim. A systematic optimization was performed to find that...

The industrial production of chitosan, initiated over 50 years ago, has transformed its application across diverse industries, agriculture, and medicine. To enhance its properties, numerous chitosan derivatives have been synthesized. The quaternization of chitosan has proven beneficial, as it not only enhances its properties but also imparts water...

The combination of wearable devices with the Internet of Things (IoT) and machine learning technologies has led to innovative analytical tools with potential applications in different fields, ranging from healthcare to smart agriculture. In this chapter, we provide an overview of the application of machine learning algorithms to wearable technologi...

Machine learning is increasingly used in the analysis of distinct types of data for clinical diagnosis and monitoring the environment, particularly because of the large amounts of data generated in sensing and biosensing methods. In this chapter, we discuss the usage of machine learning for electrochemical sensors, with emphasis on colorimetric pri...

We report a nanoarchitectonic electronic tongue made with flexible electrodes coated with curcumin carbon dots and zein electrospun nanofibers, which could detect Staphylococcus aureus(S. aureus) in milk using electrical impedance spectroscopy. Electronic tongues are based on the global selectivity concept in which the electrical responses of disti...

The efficiency of methylene blue (MB) and acridine orange (AO) for photodynamic therapy (PDT) is increased if encapsulated in liposomes. In this paper we determine the molecular-level interactions between MB or AO and mixed monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG...

Thermoelectric materials capable of converting heat into electrical energy are used in sustainable electric generators, whose efficiency has been normally increased with incorporation of new materials with high figure of merit (ZT) values. Because the performance of these thermoelectric generators (TEGs) also depends on device geometry, in this stu...

Reconfigurable magnetoplasmonic nanoantennas will enable on-chip wireless communication of a single nanoantenna with multiple nanoantennas, improving energy efficiency and miniaturization density levels.

We report on a flexible, bifunctional platform made with solution-blow spinning fiber mats of polylactic acid (PLA) and polyethylene glycol (PEG). The PLA/PEG mats were designated bifunctional because they were used as a substrate for screen-printed carbon electrodes (SPCEs) and as a matrix to attach glucose oxidase (GOx) covalently. By attaching G...

Chemoselective oxidation of sulfides to sulfones under mild conditions is relevant for industry, but challenging owing to the need to establish catalysis mechanisms and optimize several experimental parameters. Herein, we report the synthesis of metal-based tungstates as efficient and selective catalysts for this transformation in darkness. This ca...

On-chip wireless communications require optical nanoantennas with dynamically tunable radiation patterns, which may allow for higher integration with multiple nanoantennas instead of two fixed nanoantennas in existing approaches. In this paper, we introduce a concept to enable active manipulation of radiated beam steering using applied magnetic fie...

The manipulation of molecules placed in close proximity to a liquid is crucial for understanding their interactions, as in the study of antibiotics against bacteria. This can, in principle, be realized with plasmonic optical tweezers, but the heating of metals leads to the denaturing of biomolecules. In this work, we demonstrate that slotted all-di...

Herein, we introduce wearable potentiometric biosensors on screen-printed carbon electrodes (SPCEs) for on-body and on-site monitoring of urea in sweat. The biosensor architecture was judiciously designed to detect urea at different pHs and incorporate a pH sensor, thus containing polyaniline ink, urease bioink and a polyvinylchloride membrane. Ure...

Low-cost, instrument-free colorimetric tests were developed to detect SARS-CoV-2 using plasmonic biosensors with Au nanoparticles functionalized with polyclonal antibodies (f-AuNPs). Intense color changes were noted with the naked eye owing to plasmon coupling when f-AuNPs form clusters on the virus, with high sensitivity and a detection limit of 0...

A computer vision (CV) system is proposed for real-time prediction of strain by monitoring the color-changing feature of mechanochromic sensors. Pictures of the sensors subjected to calibration tensile tests were treated with standard image processing methods and analyzed using supervised machine learning (ML) algorithms. Visual strain sensing was...

Photoelectrochemical (PEC) sensors are promising for monitoring the environment and in clinical diagnosis, but their point-of-use application requires portable systems and materials with high photocatalytic activity. In this work, we extend the use of a recent miniaturized PEC system to detect the breast cancer biomarker carbohydrate antigen 15-3 (...

Drug resistance is known to depend on the interactions with cell membranes and other molecules such as human cytochromes P450 (CYPs) which are anchored on the endoplasmic reticulum (ER) membrane and involved in the metabolism of anticancer drugs. In this study, we determined the influence from cytochrome P450 3A4 (CYP3A4) on the interaction between...

Cancer is the second leading cause of death globally and early diagnosis is the best strategy to reduce mortality risk. Biosensors to detect cancer biomarkers are based on various principles of detection, including electrochemical, optical, electrical, and mechanical measurements. Despite the advances in the identification of biomarkers and the con...

This paper reports a facile technique to construct an oxide nanostructured film on a low-power microheater sensor platform to detect NO2 gas with high sensitivity and selectivity at a low temperature. Microcube-shaped zinc stannate (ZnSnO3) nanostructures prepared through a co-precipitation method were used to detect NO2 down to 85 ppb at 110 °C wi...

We report an electronic tongue based on impedance spectroscopy to detect Staphylococcus aureus and diagnose bovine mastitis in milk samples. This was achieved with optimized sensing units made with layer-by-layer films and by treating the capacitance data with machine learning algorithms employing decision trees models. These films were made with c...

Although Ag-based materials are efficient against antibiotic-resistant bacteria, their high toxicity to living organisms represents a major challenge for obtaining useful products. In this work, we report the bactericidal activity of Ag4V2O7/β-AgVO3 heterostructures, which proved to be effective against Klebsiella pneumoniae (ATCC 1706, a standard...

Machine learning and other artificial intelligence methods are gaining increasing prominence in chemistry and materials sciences, especially for materials design and discovery, and in data analysis of results generated by sensors and biosensors. In this paper, we present a perspective on this current use of machine learning, and discuss the prospec...

Flexible, fully printed immunosensors can meet the requirements of precision nutrition, but this demands optimized molecular architectures to reach the necessary sensitivity. Herein, we report on flexible and label-free immunosensor chips made with tree-like gold dendrites (AuDdrites) electrochemically formed by selective desorption of l-cysteine (...

An overview is presented of experimental investigations during two decades at the Polymer Group Prof. Bernhard Gross in Sao Carlos, Brazil, on the properties of piezoelectric polymers. The paper is focused on innovations with the introduction of the constant current technique and corona triodes. Together with thermally stimulated depolarization and...

A disposable electrochemical immunosensor for on‐site detection of aflatoxin B1(AFB1), one of the most toxic mycotoxins in agri‐food products, was fabricated through a low‐cost cut‐printing method and then modified with zein/polypyrrole(PPy) electrospun nanofibers onto which anti‐AFB1 monoclonal antibodies were immobilized covalently. Fabrication w...

The polysaccharide β-glucan, found in the cell wall of cereals such as wheat, oats, and barley, is believed to lower the concentration of bad cholesterol in humans, but the molecular-level mechanisms responsible for such an action are unknown. In this study, we use Langmuir monolayers of cholesterol and dipalmitoyl phosphatidyl choline (DPPC) as ce...

The use of enhanced electromagnetic fields in nanophotonic structures is moving from plasmonic to all-dielectric platforms in order to overcome the intrinsic Ohmic losses from metal inclusions. In this work, we demonstrate that strong electromagnetic fields may be generated in the infrared without heating the nearby molecules by exciting anapole mo...

Mass testing for the diagnosis of COVID-19 has been hampered in many countries owing to the high cost of genetic material detection. This study reports on a low-cost immunoassay for detecting SARS-CoV-2 within 30 min using dynamic light scattering (DLS). The immunosensor comprises 50-nm gold nanoparticles (AuNPs) functionalized with antibodies agai...

The membrane of methicillin-resistant Staphylococcus aureus (MRSA) contains penicillin-binding proteins (PBPs) in the phospholipidic bilayer, with the protein PBP2a being linked with the resistance mechanism. In this work we confirm the role of PBP2a with molecular-level information obtained with Langmuir monolayers as cell membrane models. The MRS...

Analytical tools are essential to monitor anthropogenic contamination of natural resources and prevent health risks to humans and other living beings, which should be low-cost, with fast response and high sensitivity. In this work we developed a photoelectrochemical (PEC) sensor to determine hydroquinone in tap water using a screen-printed carbon e...

The early diagnosis of Covid-19 requires either an accurate detection of genetic material or a sensitive detection of viral proteins. In this work, we designed an immunoassay platform for detecting trace levels of SARS-CoV-2 spike (S) protein. It is based on surface-enhanced resonance Raman scattering (SERRS) of methylene blue (MB) adsorbed onto sp...

This paper reports the development of a low-cost (< US$ 0.03 per device) immunosensor based on gold-modified screen-printed carbon electrodes (SPCEs). As a proof of concept, the immunosensor was tested for a fast and sensitive determination of S proteins from both SARS-CoV and SARS-CoV-2, by a single disposable device. Gold nanoparticles were elect...

In this study, chloroquine resinates were prepared at a 1:1 (w:w) drug-to-resin ratio using the batch method with polacrilex (PC), sodium polystyrene sulfonate (SPS), and polacrilin potassium (PP) ion exchange resins (IER). The influence of drug/resin ratio and pH of the medium on drug loading efficiency was explored. UV-VIS spectrophotometric anal...

Early diagnosis of cattle diseases such as mastitis caused by Staphylococcus aureus (S. aureus) can be made effective if on-site detection methods with portable instruments are available. In this work, we fabricated immunosensors based on a layer-by-layer (LbL) film of chitosan and carbon nanotubes coated with a layer of antibodies to detect S. aur...

Wearable sensing technology may fulfill the requirements of precision medicine, but the use of on-body devices for rapid, selective screening of therapeutic drugs is relatively new. In this paper, we report on wearable glove-embedded sensors for non-invasive and selective determination of therapeutic drugs and a biomarker in sweat samples. Electroc...

The diagnosis of cancer and other diseases using data from non-specific sensors – such as the electronic tongues (e-tongues) - is challenging owing to the lack of selectivity, in addition to the variability of biological samples. In this study, we demonstrate that impedance data obtained with an e-tongue in saliva samples can be used to diagnose ca...

We demonstrate numerically a concept for highly integrated magnetoplasmonic biosensors made with nanostructured magnetooptical (MO) hyperbolic metamaterials (HMMs). The concept is based on the use of enhanced amplitudes of ultranarrow peaks of the transverse magnetooptical Kerr effect (TMOKE). In contrast to conventional magnetoplasmonic transducer...

Low-cost sensors to detect cancer biomarkers with high sensitivity and selectivity are essential for early diagnosis. Herein, an immunosensor was developed to detect the cancer biomarker p53 antigen in MCF7 lysates using electrical impedance spectroscopy. Interdigitated electrodes were screen printed on bacterial nanocellulose substrates, then coat...

The concepts and methods of nanoarchitectonics are explored to combine materials and architectures for a variety of purposes. In this chapter we concentrate on nanostructured films where the properties of polymers, nanomaterials, and biomolecules are leveraged for various applications. To illustrate the generality and potential of nanoarchitectonic...

Glutathione-s-transferase is believed to be involved in the resistance to chemotherapeutic drugs, which depends on the interaction with the cell membranes. In this study, we employed Langmuir monolayers of a mixture of phospholipids and cholesterol (MIX) as models for tumor cell membranes and investigated their interaction with the anticancer drugs...

The assessment of drug taste is crucial for pediatric treatments so that formulations can be developed to enhance their effectiveness. In this study, in vivo and in vitro methods were applied to evaluate the taste of tablets of three drugs administered to children without taste-masking excipients to treat tropical diseases, namely artesunate-mefloq...

A sensitive detection of carbohydrate antigen 15–3 (CA15-3) levels may allow for early diagnosis and monitoring the treatment of breast cancer, but this can only be made in routine clinical practice if low-cost immunosensors are available. In this work, we developed a sandwich-type electrochemical immunosensor capable of rapid detection of CA15-3 w...

DOI:https://doi.org/10.1103/PhysRevLett.127.279901

We report on the preparation of SiO2-based nanoparticles readily available for superhydrophobic applications. In contrast to usual approaches, our process is substrate-free and based on electrostatic adsorption of small SiO2 particles onto large SiO2 cores with the aid of poly(diallyldimethylammonium chloride) followed by calcination and chemical m...

PROCESSING AND APPLICATION OF POLYMERIC BIOMATERIALS: RECENT ADVANCES AND PERSPECTIVES. Biomaterials have been intensively investigated due to the increase in the elderly population and high prevalence of several disorders, such as cardiovascular and orthopedic diseases. Polymeric and composite polymeric materials in combination with different proc...

On-site monitoring the presence of pesticides on crops and food samples is essential for precision and post-harvest agriculture, which demands nondestructive analytical methods for rapid, low-cost detection that is not achievable with gold standard methods. The synergy between eco-friendly substrates and printed devices may lead to wearable sensors...

Photoinduced hyperthermia with nanomaterials has been proven effective in photothermal therapy (PTT) of tumor tissues, but a precise control in PTT requires determination of the molecular-level mechanisms. In this paper, we determined the mechanisms responsible for the action of photoexcited gold shell-isolated nanoparticles (AuSHINs) in reducing t...

Mass testing for the diagnostics of COVID-19 has been hampered in many countries owing to the high cost of the methodologies to detect genetic material of SARS-CoV-2. In this paper, we report on a low-cost immunosensor capable of detecting the spike protein of SARS-CoV-2, including in samples of inactivated virus. Detection is performed with electr...

The concepts and methods of nanoarchitectonics are explored to combine materials and architectures for a variety of purposes. In this chapter we concentrate on nanostructured films where the properties of polymers, nanomaterials, and biomolecules are leveraged for various applications. To illustrate the generality and potential of nanoarchitectonic...

A challenge in plasmonic trapping of small nanoparticles is the heating due to the Joule effect of metallic components. This heating can be avoided with electromagnetic field confinement in high-refractive-index materials, but nanoparticle trapping is difficult because the electromagnetic fields are mostly confined inside the dielectric nanostructu...

Plasmonic and magnetic silicon hybrids are suitable hyperthermia nanoagents owing to their ability to generate heat under an external stimulus in addition to their biocompatibility, limited aggregation, dielectric properties, and surface functionalization. In this chapter, a discussion will be provided the applications of plasmonic and magnetic sil...

Multiplex detection of emerging pollutants is essential to improve quality control of water treatment plants, which requires portable systems capable of real-time monitoring. In this paper we describe a flexible, dual electrochemical sensing device that detects nonylphenol and paroxetine in tap water samples. The platform contains two voltammetric...

Langmuir monolayers are used to simulate the biological membrane environment, acting as a mimetic system of the outer or the inner membrane leaflet. Herein, we analyze the interaction of membrane models with a partially N-acetylated chitosan (Ch35%) possessing a quasi-ideal random pattern of acetylation, full water solubility up to pH ≈ 8.5 and unu...

In this paper we discuss how nanotech-based sensors and biosensors are providing the data for autonomous machines and intelligent systems, using two metaphors to exemplify the convergence between nanotechnology and artificial intelligence (AI). These are related to sensors to mimic the five human senses, and integration of data from varied sources...

Highly sensitive and selective gas sensors with low energy consumption and amenable to miniaturization are required for real-time gas monitoring applications. The challenge is to produce sensing units at a sufficiently low cost to allow for broad deployment, which can only be reached with efficient materials and fabrication procedures. In this cont...

We report on genosensors to detect an ssDNA sequence from the SARS-CoV-2 genome, which mimics the GU280 gp10 gene (coding the viral nucleocapsid phosphoprotein), using four distinct principles of detection and treating the data with information visualization and machine learning techniques. Genosensors were fabricated on either gold (Au) interdigit...

Boron nitride allotropes are 2D nanomaterials with hexagonal form, sometimes referred to as “white graphene.” In contrast to graphene, boron nitride is a dielectric material with a well-defined energy gap, being therefore suitable for several electronic devices. Its use in sensors and biosensors has been relatively little explored though. In this c...

Electrical impedance spectroscopy has been used extensively for sensing and biosensing due to the multiple electrical properties that can be interrogated through varying the frequency of the electrical excitation. In this paper, we review the basic concepts and key issues for applying impedance spectroscopy in sensing and biosensing, with emphasis...

A series of precursors of bioactive paraconic acids were synthesized and their cytotoxicity assessed on human cells in vitro. Two amphiphilic nitro-containing precursors, Nitro-C15-EED and the butanolide Nitro-C12-GBL, were cytotoxic at the micromolar scale, with higher activity on tumor HeLa cells than on HEK-293T of non-tumor origin. The structur...

In this paper we present a portable photoelectrochemical system developed with screen-printed carbon electrodes (SPCEs) and a 3 W light-emitting diode (LED). The device with 3D printed structure was applied for detecting lactate on TiO2 nanoparticles modified with [Ni(salen)] polymer film (referred to as TiO2@poly[Ni(salen)]). Electrode coating wit...

https://pubs.rsc.org/en/content/articlelanding/2021/tc/d1tc90093e#!divAbstract

In this paper we report on a modular design that allows one to fabricate electrochemical sensors upon combining 3D printing and screen printing. The usefulness of the design is showcased with graphene paste electrodes (GPE) coated with magnetic microspheres used to detect the drug nimesulide (NIM), biomarkers dopamine (DOP) and uric acid (UA). Unde...

Monitoring health conditions with low-cost, portable devices is a target for diseases such as diabetes, which is now performed by detecting the glucose level in blood samples. Since commercial biosensors suffer with limited enzyme stability and shelf-life problems, novel materials have been exploited, including metal oxides and sulfide nanostructur...

The composition of Langmuir monolayers used as cell membrane models is an essential factor for the interaction with biologically-relevant molecules, including pharmaceutical drugs. In this paper, we report the modulation of effects from the antineoplastic drug paclitaxel by the relative concentration of cholesterol in the Langmuir monolayers of ter...