## 3 Protein and Peptide Nanobiosensors for the Early Diagnosis of Diseases  
A pathological process at an early stage is characterized by the appearance of marker proteins at very low (10\({}^{-15}\) M and lower) concentrations in blood, and highly-sensitive nanobiosensor systems are required to detect proteins at such low concentrations [10]. Additionally, the composition of biomolecules gathering at a surface is another relevant issue, given the dynamic nature of disease progression. With respect to that, nano-biosensors may offer increased possibilities for the early diagnosis of diseases. In the manuscript: _Influence of Chip Materials on Charge Generation in Flowing Solution in Nanobiosensors_[11], [PERSON] and coworkers demonstrate that the presence of an AFM chip (made of mica and graphite) near the nozzle of the injector supplying an analyte solution into the measuring cell of an AFM-based fishing system (used for the registration of low-abundant proteins in the temperature range corresponding to the physiological temperature of 35 \({}^{\circ}\)C) causes an increase in charge generation upon the injection of the solution. In the presence of protein at femtomolar concentrations, an increase in the efficiency of charge generation in the injector was demonstrated. [PERSON] and coworkers in their paper on _Metallic Nanoparticles Obtained via \"Green\" Synthesis as a Platform for Biosensor Construction_[12] demonstrate the possibility of developing reagent-less, enzyme-based amperometric biosensors using metallic nanoparticles obtained via green synthesis (gNPs), which have great potential for applications in biotechnology, industry, and medicine as antibacterial agents, fluorescent markers, and carriers for drug delivery, respectively. The bioelectrodes modified with Pd-based gNPs have lower sensitivities to their substrates, but broader linear ranges of their detection and higher storage stabilities than unmodified control electrodes. Moreover, the advantage of the \"green\" approach is the rapid growth of the yeast cells with a high-yield of pure gNPs surrounded by organic compounds that provides the anti-aggregative effect on metallic gNPs, which can be useful as carriers of enzymes and cells in biosensors and biofuel cells. In the article on _The Characterisation and Quantification of Immobilised Concanavalin A on Quartz Surfaces Based on The Competitive Binding to Glucose and Fluorescent Labelled Dextran_[13] authored by [PERSON] and coworkers, a simple protocol for the immobilization of Concanavalin A (Con A) on a quartz substrate, a common material for gravimetric microsensors, was developed. The binding activity of the immobilized Con A was assessed by measuring the intensity from fluorescent labelled dextran (FITC and Alexa 488; with a surface coverage ranging from \(1.8\times 10^{11}\) to \(2.1\times 10^{12}\) immobilized fluorescent molecules per cm\({}^{2}\)) over a glucose concentration range from 0 to 40 mM, whereas any structural changes to the surface topography were investigated using AFM. These complementing measurements verified that a change in the fluorescence intensity was accompanied with a change in the average surface roughness, and thereby the composition (addition and loss of dextran) at the sample surface. [PERSON] and coworkers in their paper on the _Study of the Stability of Functionalized Gold Nanoparticles for the Colorimetric Detection of Dipeptidyl Peptides IV_[14] report on three stabilization strategies of gold nanoparticles and their practical applications for the visual detection of dipeptidyl peptidase IV (DPP-IV), an enzyme of high clinical importance, especially as a diagnostic and prognostic marker of various inflammatory disorders and tumors. The first strategy used the incorporation of a PEGylated sequence with a dithiol anchor to create biorecognition ligands; the other two strategies used a peptide sequence (CALNN) selected from 58 peptide sequences tested for their high stability and resistance to electrolyte-induced Au NP aggregation.