Voltammetric DNA sensor has been proposed on the platform of glassy carbon electrode covered with carbon black with adsorbed pillar[5]arene molecules. Electropolymerization of Neutral Red performed in the presence of native or oxidatively damaged DNA resulted in formation of hybrid material which activity depended on the DNA conditions. The assembling of the surface layer was confirmed by scanning electron microscopy and electrochemical impedance spectroscopy. The influence of DNA and pillar[5]arene on redox activity of polymeric dye was investigated and a significant increase of the peak currents was found for DNA damaged by reactive oxygen species generated by Cu²⁺/H₂O₂ mixture. Pillar[5]arene improves the electron exchange conditions and increases the response and its reproducibility. The applicability of the DNA sensor developed was shown on the example of ascorbic acid as antioxidant. It decreases the current in the concentration range from 1.0 μM to 1.0 mM. The possibility to detect antioxidant activity was qualitatively confirmed by testing tera infusion. The DNA sensor developed can find application in testing of carcinogenic species and searching for new antitumor drugs.

The detection of small molecules interacting with DNA is important for the assessment of potential hazards related to the application of rather toxic antitumor drugs, and for distinguishing the factors related to thermal and oxidative DNA damage. In this work, a novel electrochemical DNA sensor has been proposed for the determination of antitumor drugs. For DNA sensor assembling, a glassy carbon electrode was modified with carbon black dispersed in DMF. After that, pillar [5]arene was adsorbed and Methylene blue and Neutral red were consecutively electropolymerized onto the carbon black layer. To increase sensitivity of intercalator detection, DNA was first mixed with water-soluble thiacalixarene bearing quaternary ammonium groups in the substituents at the lower rim. The deposition of the mixture on the electropolymerized dyes made it possible to detect doxorubicin as model intercalator by suppression of the redox activity of the polymerization products. The DNA sensor made it possible to determine 0.5 pM–1.0 nM doxorubicin (limit of detection 0.13 pM) with 20 min of incubation. The DNA sensor was successfully tested on spiked samples of human plasma and doxorubicin medication.

We proposed a voltammetric DNA sensor based on glassy carbon modified with carbon black, pillar[5]arene, and electropolymerized Neutral Red. To increase signal sensitivity, Methylene Blue in monomeric and polymeric forms was introduced into the surface layer of the DNA sensor as a specific DNA intercalator and electron transfer mediator. The electrochemical characteristics of the coating are determined, depending on the composition and the preparation method; a consistent change in the peak currents of dyes is observed during the incubation of a DNA sensor in a solution of doxorubicin as a model anticancer drug. Under optimal conditions, the DNA sensor enables the determination of 10 nM to 0.1 mM of doxorubicin. Doxorubicin can also be determined in synthetic blood plasma.

Electrochemical enzyme biosensors are extensively utilized in clinical analysis and environmental monitoring, yet achieving effective enzyme immobilization while maintaining high activity remains a challenge. In this work, we developed a flow-through enzyme biosensor system using a 3D-printed flow-through electrochemical cell fabricated from commercially available poly (lactic acid). After modification with thiacalixarene-functionalized oligo (lactic acids) (OLAs), the material enabled efficient immobilization of uricase on the inner surface of a replaceable reactor of the cell. Swelling and hydrolytic stability of OLAs in cone, partial cone, and 1,3-alternate conformations were studied, with 1,3-alernate conformation demonstrating superior stability and enzyme immobilization performance. The use of OLAs enhanced immobilization efficiency by over 30% and protected the reactor from swelling, hydrolytic degradation, and enzyme loss. The biosensor was validated for amperometric uric acid determination, with a screen-printed carbon electrode modified with carbon black and Prussian Blue. This modification reduced the cathodic potential for uric acid detection to –0.05 V. The biosensor exhibited a linear detection range of 10 nM to 30 μM with a detection limit of 7 nM, and it performed effectively in artificial urine and synthetic blood plasma. The novel cell design, featuring easy assembly and low-cost replaceable parts, makes this biosensor a promising candidate for routine clinical analysis and other practical applications.

Electrochemical flow-through sensor based on pillar[3]arene[2]quinone (P[3]A[2]Q) derivative was developed. Nitrophenol determination was based on P[3]A[2]Q redox current changes. Also, the shift of cathodic potential was observed compared to nitrophenol reduction current registration directly. Using carbon black (CB) as a matrix for macrocycle implementation provided the sensor stability in the flow when it was applied with a 3D printed flow-through cell. CB and macrocycle were drop casted from the same aliquot providing one-step modifying layer production by the principle of “one-pot synthesis”. The flow-through chronoamperometric sensor designed allowed determining mononitrophenols in the concentration range of 1 nM – 0.1 mM with the limit of detection (LOD) of 0.5 nM. The linear concentration range of 10 nM – 0.1 mM with LOD of 2 nM was obtained for 2,4-dinitrophenol, 2,6-dinitrophenol and 2,4,6-trinitrophenol. The sensor proposed was tested with a model effluent sample, and sufficient recovery about 98±1% was obtained.

The approaches to the synthesis of newly obtained pillar[3]arene[2]hydroquinone and its derivative with functional ammonium substituents (P[3]A[2]HQae) are suggested. The structures of the macrocycles synthesized were confirmed and characterized by a complex of physical methods. P[3]A[2]HQae has found its application as an electron transfer mediator for the determination of dopamine and ascorbic acid with the voltammetric sensor developed. For a successful sensor assembly the glassy carbon electrode (GCE) was modified with carbon black (CB), P[3]A[2]HQae and electropolymerized form of Neutral red (polyNR). P[3]A[2]HQae demonstrated better mediator properties compared to unsubstituted pillar[5]arene due to the 5–6-fold increase in the redox currents of Neutral red (NR) during its electropolymerization. Under optimal conditions the sensor allowed performing the determination of dopamine and ascorbic acid in the ranges from 10 nM to 1.0 mM and from 1 nM to 1 mM, respectively. The limits of detection were of 10 nM for dopamine and and 1 nM for ascorbic acid. The polyNR peaks positions after its interaction with the analytes provided the opportunity to discriminate the sensor response towards dopamine and ascorbic acid. The possibility of dopamine and ascorbic acid determination in real drug samples was demonstrated.