Comparison of Survivin Determination by Surface-Enhanced Fluorescence and Raman Spectroscopy on Nanostructured Silver Substrates.

Survivin belongs to a family of proteins that promote cellular proliferation and inhibit cellular apoptosis. Its overexpression in various cancer types has led to its recognition as an important marker for cancer diagnosis and treatment. In this work, we compare two approaches for the immunochemical detection of survivin through surface-enhanced fluorescence or Raman spectroscopy using surfaces with nanowires decorated with silver nanoparticles in the form of dendrites or aggregates as immunoassays substrates.

Photonic Dipstick Immunosensor to Detect Adulteration of Ewe, Goat, and Donkey Milk with Cow Milk through Bovine κ-Casein Detection.

The quality and authenticity of milk are of paramount importance. Cow milk is more allergenic and less nutritious than ewe, goat, or donkey milk, which are often adulterated with cow milk due to their seasonal availability and higher prices. In this work, a silicon photonic dipstick sensor accommodating two U-shaped Mach-Zehnder Interferometers (MZIs) was employed for the label-free detection of the adulteration of ewe, goat, and donkey milk with cow milk.

Electrochemical Aptasensor with Antifouling Properties for Label-Free Detection of Oxytetracycline.

Oxytetracycline (OTC) is a widely employed antibiotic in veterinary treatment and in the prevention of infections, potentially leaving residues in animal-derived food products, such as milk, that are consumed by humans. Given the detrimental effects of prolonged human exposure to antibiotics, it has become imperative to develop precise and sensitive methods for monitoring the presence of OTC in food. Herein, we describe the development and results of a preliminary label-free electrochemical aptasensor with antifouling properties designed to detect OTC in milk samples.

Multiplexed colorimetric assay of antioxidants in wines with paper-based sensors fabricated by pen plotting.

This work reports the development of low-cost and rapid multiplexed colorimetric assay of antioxidants (total phenolics, antioxidant capacity, flavonoids and anthocyanins) in wines at daisy-shaped fluidic paper-based analytical devices (PADs). The desired fluidic patterns were formed on paper by pen drawing and colorimetric reagents were immobilized at the 6 peripheral test zones. The sample was added at the central sample zone, migrated to the test zones and reacted with the immobilized reagents producing characteristic colors that were captured and analyzed.

A simplified lateral flow immunosensor for the assay of carcinoembryonic antigen in low-resource settings.

Carcinoembryonic antigen (CEA) is a glycoprotein widely used as a tumor marker. In this work, a colorimetric lateral flow immunosensor is developed for rapid and low-cost quantification of CEA in human blood serum. The immunosensor consists of a glass fiber sample/conjugation pad, a nitrocellulose detection pad and a cellulose absorption pad.

Effect of in vivo aging on the surface and electrochemical properties of magnetic attachments used in facial prostheses: A retrieval analysis study.

Statement Of Problem: Reasons associated with the failure of facial prosthesis are of major concern and may be associated with deterioration of both elastomeric materials and magnetic attachments. However, the extent of deterioration of these components is unclear.

Purpose: The purpose of this in vitro study was to evaluate selected retrieved facial prostheses and provide information regarding the electrochemical characterization of the recovered magnetic attachments.

An Aptamer-Based Lateral Flow Biosensor for Low-Cost, Rapid and Instrument-Free Detection of Ochratoxin A in Food Samples.

In this work, a simple and cost-efficient aptasensor strip is developed for the rapid detection of OTA in food samples. The biosensor is based on the lateral flow assay concept using an OTA-specific aptamer for biorecognition of the target analyte. The strip consists of a sample pad, a conjugate pad, a nitrocellulose membrane (NC) and an absorbent pad.

Cancer Marker Immunosensing through Surface-Enhanced Photoluminescence on Nanostructured Silver Substrates.

Nanostructured noble metal surfaces enhance the photoluminescence emitted by fluorescent molecules, permitting the development of highly sensitive fluorescence immunoassays. To this end, surfaces with silicon nanowires decorated with silver nanoparticles in the form of dendrites or aggregates were evaluated as substrates for the immunochemical detection of two ovarian cancer indicators, carbohydrate antigen 125 (CA125) and human epididymis protein 4 (HE4). The substrates were prepared by metal-enhanced chemical etching of silicon wafers to create, in one step, silicon nanowires and silver nanoparticles on top of them.

Paper-Based Aptasensors: Working Principles, Detection Modes, and Applications.

Aptamers are short oligonucleotides designed to possess high binding affinity towards specific target compounds (ions, molecules, or cells). Due to their function and unique advantages, aptamers are considered viable alternatives to antibodies as biorecognition elements in bioassays and biosensors. On the other hand, paper-based devices (PADs) have emerged as a promising and powerful technology for the fabrication of low-cost analytical tools, mainly intended for on-site and point-of-care applications.

Eco-friendly voltammetric platform for trace metal determination using a conductive polymer sensor modified with bismuth nanoparticles generated by spark discharge.

The fabrication of a low-cost eco-friendly sensor platform for the voltammetric determination of trace metals by electrochemical stripping analysis is reported. Plastic conductive electrodes were manufactured via injection moulding from polysterene reinforced with carbon fibres. The platform comprises a carbon counter electrode, a working electrode modified with bismuth nanoparticles generated by spark discharge and a reference electrode coated with AgCl.

Electrochemical Determination of the Drug Colchicine in Pharmaceutical and Βiological Samples Using a 3D-Printed Device.

In this work, a simple, fast, and sensitive voltammetric method for the trace determination of the alkaloid drug colchicine (Colc) using a 3D-printed device is described. The electrochemical method was based on the adsorptive accumulation of the drug at a carbon-black polylactic acid (CB/PLA) working electrode, followed by voltammetric determination of the accumulated species. The plastic sensor was printed in a single step by a low-cost dual extruder 3D-printer and featured three CB/PLA electrodes (serving as working, reference, and counter electrodes) and a holder, printed from a non-conductive PLA filament.

Mach-Zehnder Interferometric Immunosensor for Detection of Aflatoxin M1 in Milk, Chocolate Milk, and Yogurt.

Aflatoxin M1 (AFM1) is detected in the milk of animals after ingestion of aflatoxin B1-contaminated food; since 2002, it has been categorized as a group I carcinogen. In this work, a silicon-based optoelectronic immunosensor for the detection of AFM1 in milk, chocolate milk, and yogurt has been developed. The immunosensor consists of ten Mach-Zehnder silicon nitride waveguide interferometers (MZIs) integrated on the same chip with the respective light sources, and an external spectrophotometer for transmission spectra collection.

Gold nanoparticle-modified sustainable plastic sensor chip for voltammetric monitoring of Hg(II).

Mercury is a toxic environmental contaminant that can cause serious health problems. This work describes a new type of eco-friendly three-electrode plastic sensor chip for the determination of trace Hg(II) by means of anodic stripping voltammetry (ASV). The sensor chip is entirely fabricated by injection moulding, which is a sustainable manufacturing method, and consists of three conductive carbon-based electrodes embedded in a plastic holder while the reference electrode is coated with Ag using e-beam evaporation.

3D-printed electrochemical glucose device with integrated Fe(II)-MOF nanozyme.

Estimation of glucose (GLU) levels in the human organism is very important in the diagnosis and monitoring of diabetes. Scientific advances in nanomaterials have led to the construction of new generations of enzymatic-free GLU sensors. In this work, an innovative 3D-printed device modified with a water-stable and non-toxic metal-organic framework of iron (Fe(II)-MOF), which serves as a nanozyme, has been developed for the voltammetric determination of GLU in artificial sweat.

Wooden Tongue Depressor Multiplex Saliva Biosensor Fabricated via Diode Laser Engraving.

Since wood is a renewable, biodegradable naturally occurring material, the development of conductive patterns on wood substrates is a new and innovative chapter in sustainable electronics and sensors. Herein, we describe the first wooden (bio)sensing device fabricated via diode laser-induced graphitization. For this purpose, a wooden tongue depressor (WTD) is laser-treated and converted to an electrochemical multiplex biosensing device for oral fluid analysis.

3D Printed Voltammetric Sensor Modified with an Fe(III)-Cluster for the Enzyme-Free Determination of Glucose in Sweat.

In this work, a 3D printed sensor modified with a water-stable complex of Fe(III) basic benzoate is presented for the voltammetric detection of glucose (GLU) in acidic epidermal skin conditions. The GLU sensor was produced by the drop-casting of Fe(III)-cluster ethanolic mixture on the surface of a 3D printed electrode fabricated by a carbon black loaded polylactic acid filament. The oxidation of GLU was electrocatalyzed by Fe(III), which was electrochemically generated in-situ by the Fe(III)-cluster precursor.

Mechanical and electrochemical characterization of 3D printed orthodontic metallic appliances after in vivo ageing.

Objectives: Three-dimensional (3D) printing technology is a promising technique for fabricating custom orthodontic metallic appliances. Aim of this study was to assess the effect of intraoral aging on the mechanical / electrochemical properties of 3D-printed orthodontic metallic appliances.

Methods: Twelve molar orthodontic distalization appliances 3D-printed from cobalt chromium (Co-Cr) alloy were retrieved after intraoral use and twenty blocks fabricated under similar conditions were used as control.

Electrochemical characterization of three types of Co-Cr based alloys manufactured by casting and selective laser melting according to ISO 10271.

Objective: To characterize the effect of elemental composition and manufacturing process on the electrochemical properties of Co-Cr-Mo, Co-Cr-W and Co-Cr-Mo-W alloys.

Methods: Six Co-Cr based alloys were included in this study. All alloys are Co-Cr based alloys, classified in three different types according to their elemental composition.

Plot-on-demand integrated paper-based sensors for drop-volume voltammetric monitoring of Pb(II) and Cd(II) using a bismuth nanoparticle-modified electrode.

The fabrication of fully ink-drawn fluidic electrochemical paper-based analytical devices (ePADs) is reported for the determination of trace Pb(II) and Cd(II) by differential pulse anodic stripping voltammetry (DPASV). The fluidic pattern was formed on the paper substrate using an inexpensive computer-controlled x-y plotter and a commercial hydrophobic marker pen. Then, electrodes were deposited on the devices using a second x-y plotting step with a commercial technical pen filled with a graphite-based conductive ink prepared in house.

Wearable Electronic Finger for Date Rape Drugs Screening: From "Do-It-Yourself" Fabrication to Self-Testing.

In-house digital fabrication of low-cost sensors that can on-site and rapidly detect adulteration of alcoholic beverages with sedation drugs (known as date rape drugs, (DRDs)) and analgesics is of great importance for everyday consumers and supervisory authorities. DRDs and analgesics are administrated in spirits for "drug-facilitated sexual assault" crimes and for the reduction of the following day hangover caused by low-quality spirits, respectively. This work describes, a novel "do-it-yourself" wearable 3D printed electrochemical finger (e-finger), which enables direct, rapid, and multianalyte self-testing of the main DRDs (flunitrazepam, scopolamine, ketamine) and paracetamol via direct immersing into a spirit shot.

Single-Use Fluidic Electrochemical Paper-Based Analytical Devices Fabricated by Pen Plotting and Screen-Printing for On-Site Rapid Voltammetric Monitoring of Pb(II) and Cd(II).

This work reports the fabrication of integrated electrochemical fluidic paper-based analytical devices (ePADs) using a marker pen drawing and screen-printing. Electrodes were deposited on paper using screen-printing with conductive carbon ink. Then, the desired fluidic patterns were formed on the paper substrate by drawing with a commercial hydrophobic marker pen using an inexpensive computer-controlled x-y plotter.

3D-printed fluidic electrochemical microcell for sequential injection/stripping analysis of heavy metals.

In this paper, a 3D-printed microfluidic device is described which is suitable for sequential injection/anodic stripping voltammetric (SIA-ASV) determination of Pb(II) and Cd(II). The fluidic device is manufactured by 3D-printing in a single-step using a dual extruder 3D printer. The device is composed of a microfluidic cell (printed from a non-conductive polylactic acid (PLA) filament) and of 3 electrodes (printed from a conductive carbon-loaded PLA filament) which are integrated within the fluidic cell.

Smartphone-Addressable 3D-Printed Electrochemical Ring for Nonenzymatic Self-Monitoring of Glucose in Human Sweat.

Nowadays, there is increased demand for wearable sensors for sweat glucose monitoring in order to facilitate diabetes management in a patient-friendly and noninvasive manner. This work describes a wearable glucose monitoring device in the form of an electrochemical ring (e-ring) fabricated by 3D printing. The 3D-printed e-ring consists of three carbon-based plastic electrodes (fabricated using a conductive filament) integrated at the inner side of a ring-shaped flexible plastic holder (fabricated using a nonconductive filament).

Fast Deoxynivalenol Determination in Cereals Using a White Light Reflectance Spectroscopy Immunosensor.

Deoxynivalenol (DON) is a mycotoxin produced by certain species and found in a high percentage of wheat and maize grains cultured worldwide. Although not so toxic as other mycotoxins, it exhibits both chronic and acute toxicity, and therefore methods for its fast and accurate on-site determination are highly desirable. In the current work, we employ an optical immunosensor based on White Light Reflectance Spectroscopy (WLRS) for the fast and sensitive immunochemical label-free determination of DON in wheat and maize samples.

Rapid Drop-Volume Electrochemical Detection of the "Date Rape" Drug Flunitrazepam in Spirits Using a Screen-Printed Sensor in a Dry-Reagent Format.

Flunitrazepam is an extremely potent benzodiazepine sedative which is associated with "drug-facilitated sexual assault" when administered within an alcoholic drink. This work describes a simple electrochemical method for on-site rapid detection of flunitrazepam in untreated spirits (whiskey, vodka and gin) using a single-use screen-printed sensor (featuring graphite working and auxiliary electrodes and an Ag/AgCl reference electrode) in a dry reagent format. Analysis was performed by placing a drop of sample on the sensor, which was previously coated with dry KCl, and recording selected reduction/oxidation peaks of the target compound in a cyclic voltammetry scan.