Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025

This Special Issue, entitled “Feature Review Papers in Chemical/Bio-Sensors and Analytical Chemistry in 2025”, collates 13 review papers that present state-of-the-art findings and future challenges regarding research on gas sensors, chemical sensors, and biosensors.

The first review focuses on chemoresistive humidity sensors [1] and considers the interplay of mechanism–material–application for sensor optimization [2,3,4,5,6,7]. The key challenges for the large-scale development of the sensors are analyzed. The second review explores the promising potential of resistive-based nanostructured CeO₂ gas sensors for the detection of toxic gases [8], where methods for improving selectivity and sensitivity, as well as decreasing the working temperature, are described [9,10,11,12]. Electrical and optical biosniffers and their use for monitoring VOCs in medical diagnostics are described in the third review [13], where challenges that must be addressed prior to real-world applications are analyzed: minimizing the effect of temperature and humidity on the signal [14], integrating multisensors [15], and improving data processing [16,17,18,19].

Four review papers that focus on chemical sensors to detect pollutants in environmental matrices were published. The suitability of optical sensing platforms—colorimetry, fluorescence, chemiluminescence, near-infrared spectroscopy, surface-enhanced Raman spectroscopy, and surface plasma resonance—for pesticide analysis in food and water samples are presented in the first article [20]. Innovations in nanomaterials with improved functionality [21], as well as the integration of novel technologies in microfluidics [22] and data processing [23], will pave the way for commercialization. The emerging role of manganese-based nanoparticles in the detection of heavy metals in environmental matrices is reviewed in the second article [24]. Although detection limits in the sub-ppb range have been reached [25], future research directions should explore practical environmental applications, such as scalability, cost effectiveness, and integration in water treatment infrastructures. The third article [26] presents green strategies, based on the AGREEMIP tool [27], regarding molecular imprinted polymers (MIPs) for chemical sensors, with the aim of improving environmental sustainability, including lifecycle and fabrication routes. The fourth article presents microfluidic technologies that integrate miniaturization, rapid analysis, and reduced reagent consumption, and allow or the real-time monitoring of heavy metal ions in environmental matrices [28]. Bringing these technologies to the forefront of environmental monitoring remains challenging, with the stability and reproducibility of the sensors and integration of advanced data processing proving difficult [29].

Six review articles focus on biosensors. The first article demonstrates the potential of electrochemical miRNA biosensors in terms of high sensitivity, short protocol, and good specificity [30]. Challenges that should be addressed prior to their widespread clinical implementation are analyzed, such as robust multi-analyte detection [31,32], wearable instrumentation [33], and clinical validation. The fluorescent detection of pathogenic bacteria that threaten human health is reviewed in the second article [34]. Lower detection limits were obtained when combining specific recognition with nanomaterial-based probes [35,36,37,38,39,40,41,42]. Major challenges remain, including minimizing background interferences and improving the sensitivity of detection. The third article assesses the degree of glycosylation of biomolecules necessary for the diagnosis of some diseases, such as cancers [43]. Electrochemical biosensors are suitable candidates for this application, even in blood samples [44,45,46]. New detection probes and integration in microfluidic systems will pave the way for new applications. The fourth article shows that in the field of ISFET technology-based biosensors, sub-picomolar sensitivities can be achieved by combining nanoporous materials and miniaturized transistors [47]. Several configurations led to sub-Nernstian sensitivities [48,49,50], and transistors based on silicon nanowires had detection limits at the closest level to single-molecule detection [51,52,53]. The fifth article presents a combination of enzymatic catalysis and single solid-state nanochannel technology, which leads to a variation in ionic current in the presence of the enzymatic substrate in these nanofluidic devices [54]. The main drawback of the nanodevices is the lack of stability, and several methods of improvement have been proposed [55,56], such as pretreatments for limiting ionic interferences [57,58,59]. Progress in microfluidic paper-based glucose sensors in POCT applications is presented in the sixth article [60]. Colorimetric and electrochemical transducers associated with enzymatic- or non-enzymatic [61,62]-sensitive parts are described. An especially strong research interest has been shown in machine learning assistance [63,64] and AI [65,66].