Fabrication and characterization of disposable sensors and biosensors for detection of formaldehyde

Recent Advances in Electrochemical Sensors for Formaldehyde

Formaldehyde, a ubiquitous indoor air pollutant, plays a significant role in various biological processes, posing both environmental and health challenges. This comprehensive review delves into the latest advancements in electrochemical methods for detecting formaldehyde, a compound of growing concern due to its widespread use and potential health hazards. This review underscores the inherent advantages of electrochemical techniques, such as high sensitivity, selectivity, and capability for real-time analysis, making them highly effective for formaldehyde monitoring. We explore the fundamental principles, mechanisms, and diverse methodologies employed in electrochemical formaldehyde detection, highlighting the role of innovative sensing materials and electrodes. Special attention is given to recent developments in nanotechnology and sensor design, which significantly enhance the sensitivity and selectivity of these detection systems. Moreover, this review identifies current challenges and discusses future research directions. Our aim is to encourage ongoing research and innovation in this field, ultimately leading to the development of advanced, practical solutions for formaldehyde detection in various environmental and biological contexts.

IoT Electrochemical Sensor with Integrated Ni(OH)2-Ni Nanowires for Detecting Formaldehyde in Tap Water

Simple, low-cost methods for sensing volatile organic compounds that leave no trace and do not have a detrimental effect on the environment are able to protect communities from the impacts of contaminants in water supplies. This paper reports the development of a portable, autonomous, Internet of Things (IoT) electrochemical sensor for detecting formaldehyde in tap water. The sensor is assembled from electronics, i.e., a custom-designed sensor platform and developed HCHO detection system based on Ni(OH)₂-Ni nanowires (NWs) and synthetic-paper-based, screen-printed electrodes (pSPEs). The sensor platform, consisting of the IoT technology, a Wi-Fi communication system, and a miniaturized potentiostat can be easily connected to the Ni(OH)₂-Ni NWs and pSPEs via a three-terminal electrode. The custom-made sensor, which has a detection capability of 0.8 µM/24 ppb, was tested for an amperometric determination of the HCHO in deionized (DI) and tap-water-based alkaline electrolytes. This promising concept of an electrochemical IoT sensor that is easy to operate, rapid, and affordable (it is considerably cheaper than any lab-grade potentiostat) could lead to the straightforward detection of HCHO in tap water.

A new electroanalytical methodology for the determination of formaldehyde in wood-based products

A new electroanalytical methodology was developed for the sensitive and selective determination of formaldehyde in wood-based products (WBPs), featuring an extraction process using a Headspace Liquid Acceptor System (HLAS), and detection by square-wave voltammetry (SWV) on unmodified screen-printed carbon electrodes (SPCEs). HLAS, here presented for the first time, captures and derivatizes formaldehyde released from the sample by using the acetylacetone reagent as acceptor solution. The product of formaldehyde with acetylacetone, in the presence of ammonium salt, is 3,5-diacetyl-1,4-dihydrolutidine (DDL) which we have found to be electrochemically active at unmodified SPCEs, generating a selective oxidation peak at +0.4 V. Detection and quantification limits of 0.57 and 1.89 mg kg^-1 were obtained, together with intra- and inter-day precisions below 10% (as relative standard deviation, RSD). The methodology was used to determine formaldehyde content in seven WBPs, with similar results being obtained by the developed HLAS-SPCE method and the European standard method EN 717-3, with a profound reduction of total analysis time. The developed HLAS-SPCE combines the use of a new sample preparation procedure for volatiles with, as far as we know, the first determination of formaldehyde (as the derivative product, DDL) on unmodified SPCEs, offering a promising alternative for the determination of formaldehyde in WBPs and other samples.

A Self-Powered Biosensor with a Flake Electrochromic Display for Electrochemical and Colorimetric Formaldehyde Detection

The formaldehyde biosensors with the features of cost effectiveness, high specificity, easy operation, and simplicity are urgently desired in routing and field detection of formaldehyde. Here, we report a new design of an enzymatic self-powered biosensor (ESPB) toward formaldehyde detection. The ESPB involves a formaldehyde dehydrogenase/poly-methylene green/buckypaper bioanode as the sensing electrode and a Prussian blue/Au nanoparticles/carbon fiber paper cathode as the electrochromic display. Formaldehyde acts as the fuel to drive the ESPB, relying on that the concentration of formaldehyde can be determined with the ESPB by both directly measuring the variance in short circuit current and observing the color change of the cathode. By measuring the variance in short circuit current, a linear detection range from 0.01 to 0.35 mM and a calculated detection limit of 0.006 mM are obtained, comparable to or better than those reported before. The color change of the cathode can be distinguished easily and exactly via the naked eye after immersing the ESPB in formaldehyde solution for 90 s with the concentration up to 0.35 mM, covering the permissive level of formaldehyde in some standards associated with environmental quality control. Specially, the formaldehyde concentration can be precisely quantified by analyzing the color change of the cathode digitally using the equation of B/(R + G + B). In the following test of real spiked samples of tap water and lake water, the recovery ratios of formaldehyde with the concentrations from 0.010 to 0.045 mM are tested to be between 95 and 100% by both measuring the variance in short circuit current and analyzing the color change of the cathode digitally. In addition, the ESPB exhibits negligible interference from acetaldehyde and ethanol and can be stored at 4 °C for 21 days with a loss of less than 8% in its initial value of short circuit current. Therefore, the ESPB with the capability of working like disposable test paper can be expected as a sensitive, simple, rapid, cost-effective colorimetric method with high selectivity in routing and field formaldehyde detection.

Responsive Photonic Hydrogel-Based Colorimetric Sensors for Detection of Aldehydes in Aqueous Solution

In this work, we present a fast and efficient strategy for the preparation of responsive photonic hydrogels for aldehyde sensing by combining the self-assembly of monodisperse carbon-encapsulated Fe₃O₄ nanoparticles (NPs) and in situ photopolymerization of polyacrylamide (PAM) hydrogels. The responsive photonic hydrogels exhibit structural color variation after being treated with formaldehyde aqueous solution, which can be attributed to the chemical reaction between the amide groups in the hydrogels and the formaldehyde. We have also shown that the photonic hydrogels can be used to determine the concentration of formaldehyde and to differentiate aldehydes through a facile reflection spectra shift and color change. This study provides a facile strategy for the visualized determination of aldehyde in aqueous solution.

Effect of Nanoparticles on Modified Screen Printed Inhibition Superoxide Dismutase Electrodes for Aluminum

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. The immobilization of the enzyme was performed with glutaraldehyde on screen-printed carbon electrodes modifiedwith tetrathiofulvalene (TTF) and different types ofnanoparticles. Nanoparticles of gold, platinum, rhodium and palladium were deposited on screen printed carbon electrodes by means of two electrochemical procedures. Nanoparticles were characterized trough scanning electronic microscopy, X-rays fluorescence, and atomic force microscopy. Palladium nanoparticles showed lower atomic force microscopy parameters and higher slope of aluminum calibration curves and were selected to perform sensor validation. The developed biosensor has a detection limit of 2.0 ± 0.2 μM for Al(III), with a reproducibility of 7.9% (n = 5). Recovery of standard reference material spiked to buffer solution was 103.8% with a relative standard deviation of 4.8% (n = 5). Recovery of tap water spiked with the standard reference material was 100.5 with a relative standard deviation of 3.4% (n = 3). The study of interfering ions has also been carried out.

The preparation of high-quality water-soluble silicon quantum dots and their application in the detection of formaldehyde

This paper reports the synthesis of water-soluble fluorescence silicon quantum dots (Si QDs) through a hydrothermal route with urea propyl triethoxysilane (UPTES) as the source of silicon and sodium citrate as the deoxidizer.

An electrochemical impedimetric sensor based on biomimetic electrospun nanofibers for formaldehyde

Herein, simple molecular recognition sites for formaldehyde were designed on electrospun polymer nanofibers.