Łukasz Górski

The widespread resistance of pathogenic bacteria to current antimicrobial drugs poses a serious challenge to modern civilization and stimulates the search for novel antibacterial agents. In this work, we investigated a series of stimuli‐responsive polymers with antibacterial properties, aiming to modulate the agent's bioactivity through external redox stimuli. The polymers were prepared via reductive amination, resulting in the grafting of ferrocene onto linear polyethyleneimine (L‐PEI). The resulting series varied in molecular weight and degree of functionalization. The redox behavior of the L‐PEI‐grafted ferrocene moieties was confirmed using UV–vis spectroscopy and cyclic voltammetry. The antimicrobial activity of each material was first assessed by determining the minimal inhibitory concentrations (MICs) against three model organisms: Escherichia coli, Staphylococcus aureus, and Candida albicans. Redox‐modulated antimicrobial activity experiments revealed an unexpected outcome. The oxidized form of L‐PEI‐Fc increased the survivability of E. coli compared to various control runs. These experiments were conducted in a nutrient‐depleted environment, and the observed effect is likely related to improved iron transport facilitated by the polymer.

We propose a novel type of electronic tongue based on four types of monodispersed chemosensory microparticles (MPs) with a lipophilic core stabilized by a nonionic poloxamer surfactant. The lipophilic core composition was designed to achieve cross-sensitivity toward various ions and to enable spectrophotometric and/or spectrofluorimetric detection. Thus, generic anion-selective MPs, generic cation-selective MPs, as well as two types of metalloporphyrin-based MPs were fabricated and their morphology was characterized. Next, their differential sensing ability toward the discrimination of five l-tyrosine derivatives (dopamine, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxy-l-phenylalanine, normetanephrine, 4-hydroxy-3-methoxymandelic acid) was assessed. Comparison with the respective ion-selective electrode (ISE) responses was also provided to verify if the results from the potentiometric e-tongue correspond to outputs of the developed MP optode array. The recognition of dietary supplements containing l-tyrosine (l-Tyr) derivatives with the use of the MP-based e-tongue proved the potential of the developed sensing assay in pharmaceutical analysis.

This paper focuses on the current state of art as well as on future trends in electrochemical aptasensors application in medical diagnostics. The origin of aptamers is presented along with the description of the process known as SELEX. This is followed by the description of the broad spectrum of aptamer-based sensors for the electrochemical detection of various diagnostically relevant analytes, including metal cations, abused drugs, neurotransmitters, cancer, cardiac and coagulation biomarkers, circulating tumor cells, and viruses. We described also possible future perspectives of aptasensors development. This concerns (i) the approaches to lowering the detection limit and improvement of the electrochemical aptasensors selectivity by application of the hybrid aptamer–antibody receptor layers and/or nanomaterials; and (ii) electrochemical aptasensors integration with more advanced microfluidic devices as user-friendly medical instruments for medical diagnostic of the future.

Purpose: Because of the bioaccumulation effect, organophosphorus pesticides cause long-term damage to mammals, even at small concentrations. The ability to perturb the phospholipid bilayer structure as well as the overstimulation of cholinergic receptors makes them hazardous to humans. Therefore, there is a need for a quick and inexpensive detection of organophosphorus pesticides for agricultural and household use. As organophosphorus pesticides are acetylcholinesterase (AChE) inhibitors, biosensors using this mechanism hold a great promise to meet these requirements with a fraction of reagents and time used for measurement comparing to laboratory methods. This study aims to manufacture AChE-coated, screen-printed carbon electrodes applicable in such amperometric biosensors. Design/methodology/approach: AChE enzyme, known for catalytic activity for the hydrolysis of acetylthiocholine (ATCh), could be used to obtain electrochemically active thiocholine from acetylthiocholine chloride in aqueous solutions. Using Malathion’s inhibitory effect towards AChE, pesticides’ presence can be detected by reduction of anodic oxidation peaks of thiocholine in cyclic voltammetry. Findings: The conducted research proved that it is possible to detect pesticides using low-cost, simple-to-manufacture screen-printed graphite (GR) electrodes with an enzymatic (AChE) coating. Investigated electrodes displayed significant catalytic activity to the hydrolysis of ATCh. Owing to inhibition effect of the enzyme, amperometric response of the samples decreased in pesticide-spiked solution, allowing determination of organophosphorus pesticides. Originality/value: Printed electronics has grown significantly in recent years as well as research focused on carbon-based nanocomposites. Yet, the utilization of carbon nanocomposites in screen-printed electronics is still considered a novelty in the market. Biosensors have proved useful not only in laboratory conditions but also in home applications, as glucometers are a superior solution for glucose determination for personal use. Although pesticides could be detected accurately using chromatography, spectroscopy, spectrometry or spectrophotometry, the market lacks low-cost, disposable solutions for pesticide detection applicable for household use. With biosensing techniques and electric paths screen-printed with GR or graphene nanocomposites, this preliminary research focuses on meeting these needs.

C‐reactive protein (CRP) is one of the crucial biomarkers of inflammation, as well as cardiovascular and cancer diseases. Hence, the development of a sensitive and selective technique for CRP detection is of special importance. One of the possibilities is the application of biosensors containing receptor elements formed of RNA aptamers, as they exhibit high affinity towards C‐reactive protein. Herein, the capability of utilization of thiolated RNA aptamers as sensing layers was verified. The occurrence of aptamer ‐ C‐reactive protein interaction was confirmed by quartz crystal microbalance experiments. The voltammetric measurements performed in the presence of methylene blue redox indicator showed a linear current decrease within 1–100 pmol L⁻¹ range of protein concentration. The interaction between surface‐tethered aptamer and CRP was distinguished with dissociation constant of 25.9 pmol L⁻¹. The developed assay demonstrated a pronounced selectivity to CRP over interfering proteins as well as capability of CRP analysis in serum sample.