Electrochemical Biosensors for Express Analysis of the Integral Toxicity of Polymer Materials

Abstract

Biosensors based on an oxygen electrode, a mediator electrode, and a mediator microbial biofuel cell (MFC) using the bacteria Gluconobacter oxydans B-1280 were formed and tested to determine the integral toxicity. G. oxydans bacteria exhibited high sensitivity to the toxic effects of phenol, 2,4-dinitrophenol, salicylic and trichloroacetic acid, and a number of heavy metal ions. The system “G. oxydans bacteria–ferrocene–graphite-paste electrode” was superior in sensitivity to biosensors formed using an oxygen electrode and MFC, in particular regarding heavy metal ions (EC50 of Cr3+, Mn2+, and Cd2+ was 0.8 mg/dm3, 0.3 mg/dm3 and 1.6 mg/dm3, respectively). It was determined that the period of stable functioning of electrochemical systems during measurements was reduced by half (from 30 to 15 days) due to changes in the enzyme system of microbial cells when exposed to toxicants. Samples of the products made from polymeric materials were analyzed using developed biosensor systems and standard biotesting methods based on inhibiting the growth of duckweed Lemna minor, reducing the motility of bull sperm, and quenching the luminescence of the commercial test system “Ecolum”. The developed bioelectrocatalytic systems were comparable in sensitivity to commercial biosensors, which made it possible to correlate the results and identify, by all methods, a highly toxic sample containing diphenylmethane-4,4′-diisocyanate according to GC-MS data.

A “2-in-1” Bioanalytical System Based on Nanocomposite Conductive Polymers for Early Detection of Surface Water Pollution

“…For the rapid assessment of BOD, the following microbial associations were formed: O. polymorpha + B. adeninivorans, P. yeei + E. coli, and B. adeninivorans + P. yeei. The electrochemical reaction with ferrocene as a model electron transport mediator does not depend on pH, and this mediator has previously been used to assess toxicity when using individual strains of microorganisms [7]. These associations can interact with ferrocene and have been confirmed by biosensor responses at a working potential of 250 mV.…”

“…Based on our previous research on the formation of receptor systems using monocultures of microorganisms for toxicity assessment [6,7], and biochemical oxygen demand (BOD) [14] under conditions involving a bioelectrocatalytic mediator, and taking into account the growth parameter characteristics, associations among microorganisms for BOD and toxicity assessment were formed (Table S1). To assess toxicity, we proposed forming the following associations: P. yeei and E. coli, E. coli and S. cerevisiae, and S. cerevisiae, and P. yeei.…”

“…The association based on E. coli bacteria and P. yeei is more stable, with the composition not differing significantly from the original 1:1 ratio (Figure S1A). This is due to similar growth parameters for the microorganisms used, including lag phase and exponential growth [7]. However, in the presence of the toxicant, there is a significant reduction in the number of viable microorganisms, which may affect the sensitivity of the bioreceptor element.…”

“…The most important integral indicators of water pollution are biochemical oxygen demand (BOD) and toxicity [4,5]. Laboratory models of biotoxicity analyzers are based on different test organisms such as fish, daphnia, algae, ciliates, duckweed, animal cells, and certain types of bacteria [6,7]. For most biotesting methods, the main disadvantage is the long duration of the analysis.…”