POC device for rapid oral pH determination based on a smartphone platform.

Salivary pH serves as a valuable and useful diagnostic marker for periodontal disease, as it not only plays a critical role in disease prevention but also in its development. Typically, saliva sampling is collected by draining and spitting it into collection tubes or using swabs. In this study, we have developed a Point-of-Care (POC) device for in situ determination of oral pH without the need for complex instruments, relying solely on a smartphone as the detection device.

Using a cotton thread-based colorimetric sensor modified by carboxymethylcellulose and cuprizone with smartphone detection for quantification of copper.

In the present work, we report the development of a novel cotton thread-based colorimetric sensor modified by carboxymethylcellulose (CMC) and cuprizone (CPZ) with smartphone detection and its application for the quantitative determination of cupric ions in water and cachaça. The cotton thread/smartphone detection-based colorimetric method is an easily affordable, low-cost technique which allows one to perform real-time and on-field determination analyses, especially with limited financial resources. The method involves the complexation of Cu(II) with CPZ, which causes a change in the coloration of the cotton thread from a shade of white to blue in the detection zone of the colorimetric sensor.

Using a biphasic system and digital imaging analysis with chemometric tools for simultaneous determination of Cu and furfural in cachaça.

The present study reports, for the first time, the development and application of a highly efficient method based on digital imaging analysis for the simultaneous determination of Cu and furfural in cachaça samples using a two-phase system and chemometrics tools. Furfural reacts with aniline in an acidic medium to form a Schiff base, which exhibits a pink color. On the other hand, Cu reacts with cuprizone in a basic medium to form a blue complex.

SARS-CoV-2 viral RNA detection using the novel CoVradar device associated with the CoVreader smartphone app.

The COVID-19 pandemic has highlighted the need for innovative approaches to its diagnosis. Here we present CoVradar, a novel and simple colorimetric method that combines nucleic acid analysis with dynamic chemical labeling (DCL) technology and the Spin-Tube device to detect SARS-CoV-2 RNA in saliva samples. The assay includes a fragmentation step to increase the number of RNA templates for analysis, using abasic peptide nucleic acid probes (DGL probes) immobilized to nylon membranes in a specific dot pattern to capture RNA fragments.

Near-Field Communication Tag for Colorimetric Glutathione Determination with a Paper-Based Microfluidic Device.

Here, we propose a microfluidic paper-based analytical device (µPAD) implemented with a near-field communication (NFC) tag as a portable, simple and fast colorimetric method for glutathione (GSH) determination. The proposed method was based on the fact that Ag could oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into oxidized blue TMB. Thus, the presence of GSH could cause the reduction of oxidized TMB, which resulted in a blue color fading.

Reversal of a Fluorescent Fluoride Chemosensor from Turn-Off to Turn-On Based on Aggregation Induced Emission Properties.

Here we present a new approach for the development of fluoride chemosensors taking advantage of aggregation induced emission (AIE) properties. Although AIE-based chemosensors have been described, they rely primarily on the analyte causing aggregation and hence fluorescence. We propose a new concept in the use of AIE for the development of fluorescent sensors.

Microanalysis based on paper device functionalized with cuprizone to determine Cu in sugar cane spirits using a smartphone.

In this work we propose for the first time, a paper-based test strip to analyse Cu content in sugar cane spirits, which, due to its simplicity, high portability and fast analytical response (3 min), can be easily applied to in situ analyses by producers. The test strip was developed aiming: i) identify qualitatively the Cu content in sugar cane spirits, and, ii) determine quantitatively the Cu content using a digital image method employing a smartphone. The paper-based test strip was functionalized with cuprizone and optimized through a Box-Behnken, an experimental design for obtaining the best reaction conditions.

Synthesis of a thermoresponsive crosslinked MEOMA polymer coating on microclusters of iron oxide nanoparticles.

Encapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (FeO) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEOMA) is successfully developed. Magnetic aggregates of large size, around 150-200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEOMA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis.

Carbon Dots as Sensing Layer for Printed Humidity and Temperature Sensors.

This work presents an innovative application of carbon dots (Cdots) nanoparticles as sensing layer for relative humidity detection. The developed sensor is based on interdigitated capacitive electrodes screen printed on a flexible transparent polyethylene terephthalate (PET) film. Cdots are deposited on top of these electrodes.

A vinyl sulfone clicked carbon dot-engineered microfluidic paper-based analytical device for fluorometric determination of biothiols.

A microfluidic paper-based analytical device integrating carbon dot (CDs) is fabricated and used for a fluorometric off-on assay of biothiols. Vinyl sulfone (VS) click immobilization of carbon dots (CDs) on paper was accomplished by a one-pot simplified protocol that uses divinyl sulfone (DVS) as a homobifunctional reagent. This reagent mediated both the click oxa-Michael addition to the hydroxyl groups of cellulose and ulterior covalent grafting of the resulting VS paper to NH-functionalized CDs by means of click aza-Michael addition.

Smartphone based meat freshness detection.

In this work, a freshness colorimetric sensor has been integrated with pork meat packages. The sensor tracks rising CO levels in the package associated with meat spoilage, as CO levels increase with bacterial population. The color of the sensor changes depending on the quantity of bacteria present, therefore it can be correlated with the freshness of meat, in this case pork loin.

Portable Instrument for Hemoglobin Determination Using Room-Temperature Phosphorescent Carbon Dots.

A portable reconfigurable platform for hemoglobin determination based on inner filter quenching of room-temperature phosphorescent carbon dots (CDs) in the presence of HO is described. The electronic setup consists of a light-emitting diode (LED) as the carbon dot optical exciter and a photodiode as a light-to-current converter integrated in the same instrument. The reconfigurable feature provides adaptability to use the platform as an analytical probe for CDs coming from different batches with some variations in luminescence characteristics.

Carbon dots-inspired fluorescent cyclodextrins: competitive supramolecular "off-on" (bio)sensors.

Chromophore-appended cyclodextrins combine the supramolecular loading capabilities of cyclodextrins (CDs) with the optical properties of the affixed chromophores. Among fluorescent materials, carbon dots (CNDs) are attractive and the feasibility of CND-appended CDs as sensors has been demonstrated by different authors. However, CNDs are intrinsically heterogeneous materials and their ulterior functionalization yields hybrid composites that are not well defined in terms of structure and composition.

General-purpose passive wireless point-of-care platform based on smartphone.

A versatile, compact and low-cost analytical platform has been designed, tested and validated to be used in the point-of-care settings. This passive measurement system is powered and complemented by a standard smartphone including a programmed application for measurement configuration and data processing as well as wireless results sharing. Electrochemical and electrochemiluminescence analytical techniques can be configured and realized by this platform that employs standard screen-printed electrodes for the sample managing and off-the-shelf electronic components.

Real time monitoring of glucose in whole blood by smartphone.

A combined thread-paper microfluidic device (μTPAD) is presented for the determination of glucose in blood. The device is designed to include all the analytical operations needed: red blood cell separation, conditioning, enzymatic recognition, and colorimetric transduction. The signal is captured with a smartphone or tablet working in video mode and processed by custom Android-based software in real-time.

Acid anhydride coated carbon nanodots: activated platforms for engineering clicked (bio)nanoconstructs.

Activated carbon nanodots functionalized with acid anhydride groups (AA-CNDs) are prepared by one-pot water-free green thermolysis of citric acid. As a proof of concept of their capabilities as appealing and versatile platforms for accessing engineering nanoconstructs, the as-prepared AA-CNDs have been reacted to yield clickable CNDs. Their click bioconjugation with relevant recognizable complementary clickable sugars has led to multivalent CND-based glyconanoparticles that are non-toxic and biorecognizable.

Ionophore-Based Optical Sensor for Urine Creatinine Determination.

Creatinine is a metabolite present in urine, and its concentration is used to diagnose and monitor kidney performance. For that reason, the development of new sensors to analyze this metabolite and obtain accurate results in a short period of time is necessary. An optical disposable sensor for monitoring creatinine levels in urine is described.

Microfluidic paper-based device for colorimetric determination of glucose based on a metal-organic framework acting as peroxidase mimetic.

This work presents a microfluidic paper-based analytical device (μPAD) for glucose determination using a supported metal-organic framework (MOF) acting as a peroxidase mimic. The catalytic action of glucose oxidase (GOx) on glucose causes the formation of HO, and the MOF causes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by HO to form a blue-green product with an absorption peak at 650 nm in the detection zone. A digital camera and the iOS feature of a smartphone are used for the quantitation of glucose with the S coordinate of the HSV color space as the analytical parameter.

Tetrazine-based chemistry for nitrite determination in a paper microfluidic device.

We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink.

Development and use of specific ELISA methods for quantifying the biological activity of bevacizumab, cetuximab and trastuzumab in stability studies.

Bevacizumab (BVZ), cetuximab (CTX) and trastuzumab (TTZ) are monoclonal antibodies (mAbs) used worldwide for the treatment of several widespread kinds of cancer. They are marketed as medicines under their respective tradenames: Avastin(®), Erbitux(®) and Herceptin(®). The aim of this research was to develop in-house specific enzyme-linked immunosorbent assays (ELISA) to assess the long-term stability of these three mabs.

Surface Modified Thread-Based Microfluidic Analytical Device for Selective Potassium Analysis.

This paper presents a thread-based microfluidic device (μTAD) that includes ionophore extraction chemistry for the optical recognition of potassium. The device is 1.5 cm × 1.

The Effects of Light-Accelerated Degradation on the Aggregation of Marketed Therapeutic Monoclonal Antibodies Evaluated by Size-Exclusion Chromatography With Diode Array Detection.

Research into the effects that exposure to light can have on therapeutic proteins is essential for ensuring the quality and safety of the medicines in which they are used. It is important to understand the effects of light on aggregation to help avoid undesirable colloidal instabilities, both in the original medicines and in the formats in which they are finally administered. In this study, 5 marketed therapeutic mAbs, namely bevacizumab, cetuximab, infliximab, rituximab, and trastuzumab, were investigated for this purpose.

Evaluation of a reconfigurable portable instrument for copper determination based on luminescent carbon dots.

A portable reconfigurable platform for copper (Cu(II)) determination based on luminescent carbon dot (Cdots) quenching is described. The electronic setup consists of a light-emitting diode (LED) as the carbon dot optical exciter and a photodiode as a light-to-current converter integrated in the same instrument. Moreover, the overall analog conditioning is simply performed with one integrated solution, a field-programmable analog array (FPAA), which makes it possible to reconfigure the filter and gain stages in real time.