Novel technique for the ultra-sensitive detection of hazardous contaminants using an innovative sensor integrated with a bioreactor.

This study introduces an evaluation methodology tailored for bioreactors, with the aim of assessing the stress experienced by algae due to harmful contaminants released from antifouling (AF) paints. We present an online monitoring system equipped with an ultra-sensitive sensor that conducts non-invasive measurements of algal culture's optical density and physiological stage through chlorophyll fluorescence signals. By coupling the ultra-sensitive sensor with flash-induced chlorophyll fluorescence, we examined the dynamic fluorescence changes in the green microalga Chlamydomonas reinhardtii when exposed to biocides. Over a 24-h observation period, increasing concentrations of biocides led to a decrease in photosynthetic activity. Notably, a substantial reduction in the maximum quantum yield of primary photochemistry (FV/FM) was observed within the first hour of exposure. Subsequently, we detected a partial recovery in FV/FM; however, this recovery remained 50% lower than that of the controls. Integrating the advanced submersible sensor with fluorescence decay kinetics offered a comprehensive perspective on the dynamic alterations in algal cells under the exposure to biocides released from antifouling coatings. The analysis of fluorescence relaxation kinetics revealed a significant shortening of the fast and middle phases,  along with an increase in the duration of the slow phase, for the coating with the highest levels of biocides. Combining automated culturing and measuring methods, this approach has demonstrated its effectiveness as an ultrasensitive and non-invasive tool for monitoring the physiology of photosynthetic cultures. This is particularly valuable in the context of studying microalgae and their early responses to various environmental conditions, as well as the potential to develop an AF system with minimal harm to the environment.

Nature of Dielectric Response of Phenyl Alcohols.

Phenyl alcohols (PhAs) are an interesting class of materials, for which the dielectric response reveals only the presence of single prominent Debye-like (D) relaxation, interpreted as a genuine structural (α) process. Herein, we have performed dielectric and mechanical measurements on a series of PhAs characterized by the varying length of the alkyl chain and found that this interpretation is not valid. Analysis of the derivative of the real part of the complex permittivity together with the mechanical and light scattering data clearly indicated that the prominent dielectric D-like peak is actually a superposition of both cross-correlation between dipole-dipole (D-mode) and self-dipole correlation (α-process) and that the distinguished α-mode exhibits a similar ("generic") shape of PhAs independently to their molecular weight and applied experimental technique. Therefore, the data presented herein contribute to the whole discussion focused on the dielectric response function and universality (or diversity) of the spectral shape of the α-mode of polar liquids.

On the relationship between the Debye process in dielectric response and a dissociation-association phenomenon in phenyl alcohols.

In this paper, we have examined a series of phenyl-substituted primary monohydroxy alcohols (phenyl alcohols, PhAs), from ethanol to hexanol by means of dielectric and Fourier transform infrared (FTIR) spectroscopies supported by the mechanical investigations. The combination of both dielectric and mechanical data allows calculation of the energy barrier, Ea, for dissociation by the Rubinstein approach developed to describe the dynamical properties of self-assembling macromolecules. It was observed that the determined activation energy remains constant, |Ea,RM| ∼ 12.9-14.2 kJ mol-1, regardless of the molecular weight of the examined material. Surprisingly, the obtained values agree very well with Ea of the dissociation process determined from the FTIR data analysed within the van't Hoff relationship, where Ea,vH ∼ 9.13-13.64 kJ mol-1. Thus, the observed agreement between Ea determined by both applied approaches clearly implies that in the case of the examined series of PhAs, the dielectric Debye-like process is governed by the association-dissociation phenomenon as proposed by the transient chain model.

Fluorescence Analysis of Biocide Efficiency in Antifouling Coatings against Cyanobacteria.

This study focused on the antifouling effect of copper oxide (Cu2O)- and zineb-based coatings against Cyanothece sp. ATCC 51142 by analysing photosynthetic activity using chlorophyll fluorescence. The photoautotrophically grown cyanobacterium was exposed to toxic coatings over a short-term period of 32 h. The study showed that Cyanothece cultures are particularly sensitive to biocides (i) released from antifouling paints and (ii) exhibited by contact with the coated surfaces. Changes in the maximum quantum yield of photosystem II (FV/FM) were observed within the first 12 h of exposure to the coatings. Partial recovery of FV/FM in Cyanothece was revealed 24 h post exposure to a copper- and zineb-free coating. In this research, we proposed an analysis of the evaluation of fluorescence data to study the initial response of cyanobacterial cells to copper- and non-copper-based antifouling coatings formulated with zineb. We evaluated the dynamics of coating toxicity by determining the characteristic time constants of changes in the FV/FM. Within the most toxic paints studied, those formulated with the highest concentration of Cu2O and zineb, the estimated time constants were 3.9 times lower compared to the copper- and zineb-free paint. The use of zineb in copper-based antifouling coatings enhanced the toxic effect of paints and contributed to a faster decline in photosystem II activity in Cyanothece cells. The analysis we proposed, along with the fluorescence screening results, may be useful in evaluating the initial antifouling dynamic action against photosynthetic aquacultures.