# Special Issue \"World of Biosensing\"
## 2 (Bio)Sensing  
In light of the facts mentioned above, this Special Issue (SI), entitled \"World of Biosensing\", collected reports on the latest scientific achievements in (bio)sensing. We have reported on the development and testing of laboratory prototypes of (bio)sensors, aiming to accelerate the introduction of these sensitive and reliable experimental devices into commercial products. The analysis of recent scientific sources demonstrated that all the devices belong ultimately to two main modes of signal detection: electrochemical and optical, each group consisting of several subfamilies. Electrochemical (bio)sensors include amperometric, potentiometric, impedometric, piezoelectric piezoresistive sensors, amongst other types. Optical biosensors are based on methods of spectrophotometry, luminescence, fluorescence, surface plasmon resonance, surface-enhanced Raman scattering, atomic force spectroscopy and more [11; 12]. Looking back to the \"World of Biosensing,\" we see that various topics were addressed--primarily concerning up-to-date achievements in the development and characterization of different types of (bio)sensors used to determine quantitative changes in a target analyte or process. Eighteen papers were submitted to this Special Issue, and eleven were accepted (a 61% acceptance rate). Further, we analyze shortly the content of the papers of the current Special Issue. The first paper in the SI, authored by [PERSON] and [PERSON], presented a review of the latest achievements in the development of biosensors based on morphologically tunable conducting polymers [13]. This overview article is pivotal, since the problem of providing effective electron transfer between a biorecognition element and an electrode surface is a decisive factor in electrochemical biosensors. The authors selected conducting polymers and nanoparticles with excellent electrical, chemical, and physical properties, polymers which would improve the analytical characteristics of biosensors when used as components [13; 14; 15]. The second paper, authored by [PERSON], [PERSON], [PERSON] et al., was dedicated to hydrogen peroxide-sensitive amperometric electrodes that were developed using metallic nanoparticles as effective mimetics of natural peroxidase [14]. Catalytically active nanomaterials or nanozymes, having higher stability and a lower cost in comparison with natural enzymes, are promising platforms for further biosensor construction. The paper by [PERSON], [PERSON], [PERSON] et al. is an example of the successful application of peroxidase-like metallic nanozymes for the fabrication of arginine oxidase-based amperometric biosensors for L-arginine determination [15]. The developed biosensors, with their excellent analytical characteristics, may be used in different branches of science, medicine, and industry. Problem-solving in the high-tech development process, especially in healthcare, is very relevant today. In the article authored by [PERSON], [PERSON], [PERSON] and [PERSON], the fabrication of a rehabilitation robot to help people suffering from limited mobile ability is described [16]. For lower limb rehabilitation to be provided successfully, level walking is necessary; thus, precise terrain identification (downhill, level, and uphill) is needed. To solve this challenge, an intelligent device was proposed that contained two types of wearable sensors: electromyography-based and ground-reaction force (mechanical-based). Three papers in the SI dealt with the development of nonenzymatic optical sensors [17; 18; 19]. A gas sensor for detection of alcoholic vapors was described in the paper of [PERSON], [PERSON], [PERSON] et al. [17]. A reusable poly(lactic acid)-based sandwich-structural membrane, equipped with excellent analytical characteristics, was fabricated for vapor sorbtion, with Fourier transform infrared spectroscopy used for signal detection. The authors proposed to apply the developed chemosensor for the monitoring of the atmosphere and environmental protection. The paper of [PERSON]. [PERSON], [PERSON], [PERSON] et al.