Assessing the ecological impact of pesticides/herbicides on algal communities: A comprehensive review

The escalating use of pesticides in agriculture for enhanced crop productivity threatens aquatic ecosystems, jeopardizing environmental integrity and human well-being. Pesticides infiltrate water bodies through runoff, chemical spills, and leachate, adversely affecting algae, vital primary producers in marine ecosystems. The repercussions cascade through higher trophic levels, underscoring the need for a comprehensive understanding of the interplay between pesticides, algae, and the broader ecosystem. Algae, susceptible to pesticides via spillage, runoff, and drift, experience disruptions in community structure and function, with certain species metabolizing and bioaccumulating these contaminants. The toxicological mechanisms vary based on the specific pesticide and algal species involved, particularly evident in herbicides' interference with photosynthetic activity in algae. Despite advancements, gaps persist in comprehending the precise toxic effects and mechanisms affecting algae and non-target species. This review consolidates information on the exposure and toxicity of diverse pesticides and herbicides to aquatic algae, elucidating underlying mechanisms. An emphasis is placed on the complex interactions between pesticides/herbicides, nutrient content, and their toxic effects on algae and microbial species. The variability in the harmful impact of a single pesticide across different algae species underscores the necessity for further research. A holistic approach considering these interactions is imperative to enhance predictions of pesticide effects in marine ecosystems. Continued research in this realm is crucial for a nuanced understanding of the repercussions of pesticides and herbicides on aquatic ecosystems, mainly algae.

Pre-During-Post Lockdown Air Quality in Adyar, Chennai, India Amid COVID-19 Pandemic

The COVID-19 pandemic has shoved most of the countries to implement restrictions for transportation and all other social activities to minimize spread of disease to the people. India is the second most populated country in the world which has implemented a historical complete lockdown throughout the country from the last week of March to April 2020 with an extension up to the first week of May 2020. This lockdown has slowed down the pollution levels in most of the cities in India within the first few weeks of the lockdown. In this view, the present study discusses the air quality scenario of Chennai, one of the megacities of India, scientifically. With the aid of air quality data of the Tamil Nadu Pollution Control Board, India, for five parameters such as PM 2.5 and P.M 10, sulphur dioxide, nitrogen dioxide and air quality index, the authors correlated the pre-during-post lockdown air quality of Adyar, Chennai. The results indicated that the concentrations of particulate matter reduced to about 50 � 80 % during the lockdown compared to pre-lockdown. The concentrations of sulphur dioxide and nitrogen dioxide were decreased to 50% and 20%, respectively, within the first week of lockdown. Further the data were compared with the pollution data for the past two years (2018 and 2019). The present study gives insight on the reduction of pollution in proportion to the temporary control of pollution source at particular interval could rejuvenate the environment.

Green synthesis and characterization of titanium dioxide nanoparticles using leaf extract of Pouteria campechiana and larvicidal and pupicidal activity on Aedes aegypti

The frequent application of synthetic insecticides creates resistance among insects, including mosquitoes, and causes environmental pollution and health issues. The current work aim at assessing the possibilities to produce and characterize the titanium dioxide (TiO₂) nanoparticles (TiO₂ NPs) mediated through the aqueous leaf extract of Pouteria campechiana, and their larvicidal and pupicidal activities against Aedes aegypti. The attained results showed that the aqueous leaf extract of P. campechiana had the efficiency to fabricate TiO₂ NPs from TiO₂. Under the UV-vis spectrum analysis, a sharp peak was recorded at 320 nm, which indicated the production of TiO₂ NPs by the plant extract. The SEM analysis revealed that the synthesized TiO₂ NPs were spherical, and 5 dissimilar diffractions were detected in the XRD spectrum analysis related to the TiO₂ NPs. In FTIR analysis, a prominent peak was found at 1052.41 cm^-1, corresponding to alcohol, and confirmed metal reduction. In the EDX analysis, there was a signal of around 58.44%, confirming the decrease in Ti from TiO₂ NPs, and the remaining percentages were Ca, Al, and Mg. About 900 μg mL^-1 of TiO₂ NPs had excellent lethal activity against various larvae and pupa stages of Ae. aegypti. The attained results showed that the P. campechiana aqueous leaf extract could reduce TiO₂ into TiO₂ NPs and could be considered a mosquito control agent. Furthermore, this is the initial report about the aqueous leaf extract of P. campechiana effectively synthesizing the TiO₂ NPs with anti-mosquito activity.

Phycoremediation potential of Chlorella sp. on the polluted Thirumanimutharu river water

Rivers are the most significant natural resources that afford outstanding habitation and nourishment for numerous living organisms. Urbanization and industrialization pollute rivers rendering their water unhealthy for consumption. Hence, this work was designed to find a potential native pollutant removing algae from polluted water. The physicochemical properties of the tested river water such as Electric Conductivity (EC), turbidity, total hardness, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ca, SO²-, and NH₃, NO₃, NO₂, PO₄, Mg, F^- and Cl^- contents were not within the permissible limits. Lab-scale and field-based phycoremediation treatments with the indigenous native microalgal species, Chlorella sp. from the Thirumanimutharu river water sample were set up for 15 days with three different (Group I, II, and III) biomass densities (4 × 10⁴, 8 × 10⁴, and 12 × 10⁴ cells mL^-1). Group III of both the lab-scale and field based treatments showed the maximum reduction in the physicochemical parameters compared to the other groups. Further, the group III of the field based study showed an extensive reduction in BOD (34.51%), COD (32.53%), NO₃, NO₂, free NH₃ (100%) and increased dissolved oxygen (DO) (88.47%) compared to the lab scale study. In addition, the trace elements were also reduced significantly. The pollutant absorbing active functional moieties (O-H, CO, and CN) found on Chlorella sp. had been confirmed by Fourier-Transform Infrared Spectroscopy (FTIR) analysis. In the Scanning Electron Microscope (SEM) study, significant morphological changes on the surface of the treated Chlorella sp. were noticed compared with the untreated Chlorella sp. biomass, which also confirmed the absorption of the pollutants during treatment.

Electrospinning and Post-Spun Chain Conformations of Synthetic, Hydrophobic Poly(α-amino acid)s

Electrospinning and post-spun conformations of hydrophobic poly(α-amino acid)s are described in this study. The poly(α-amino acid)s, poly(Gly), poly(l-Ala), poly(l-Val), and poly(l-Leu) were synthesized via corresponding N-carboxy-α-amino acid anhydrides. The average molecular weight and degree of polymerization of these polymers were determined by N-terminus labeling using 2,4-dinitrofluorobenzene and by viscometry in the case of poly(Gly). These poly(α-amino acid)s were electrospun from trifluoroacetic acid or trifluoroacetic acid/dichloromethane solutions. The FT-IR spectroscopy and wide-angle X-ray diffraction indicated that the electrospun poly(l-Ala) and poly(l-Leu) fibers predominantly adopts α-helical structure, whereas poly(l-Val) and poly(Gly) fibers exhibited mainly β-strand and random coil structures, respectively.

Effect of Microgravity on Fungistatic Activity of an α-Aminophosphonate Chitosan Derivative against Aspergillus niger

Biocontamination within the international space station is ever increasing mainly due to human activity. Control of microorganisms such as fungi and bacteria are important to maintain the well-being of the astronauts during long-term stay in space since the immune functions of astronauts are compromised under microgravity. For the first time control of the growth of an opportunistic pathogen, Aspergillus niger, under microgravity is studied in the presence of α-aminophosphonate chitosan. A low-shear modelled microgravity was used to mimic the conditions similar to space. The results indicated that the α-aminophosphonate chitosan inhibited the fungal growth significantly under microgravity. In addition, the inhibition mechanism of the modified chitosan was studied by UV-Visible spectroscopy and cyclic voltammetry. This work highlighted the role of a bio-based chitosan derivative to act as a disinfectant in space stations to remove fungal contaminants.

Facile fabrication of hierarchical cellulose nanospicules via hydrolytic hydrogenation

A new spicule-like cellulose nanostructure is prepared from electrospun cellulose nanofibers using a one-pot bifunctional catalysis strategy namely hydrolytic hydrogenation. The electrospun cellulose nanofibers or cellulose film was treated in presence of catalyst consisting of an alkali and a metal to produce celluloses with structures like nanospicules, nanoflowers or nanorods, respectively. This work highlights the promising combination of electrospinning and hydrolysis/hydrogenation for facile production of hierarchical cellulose nanostructures such as nanospicules and nanorods.

Correlations between steric/thermochemical parameters and O-/N-acylation reactions of cellulose

N(α)-t-Butyloxycarbonyl (Boc)-amino acids (Xaa = Gly, Ala, or β-Ala) were reacted with the cellulose hydroxyl groups (O-acylation) using N,N'-carbonyl diimidazole. The degrees of substitution toward the total hydroxyl groups (DS%(/OH)s) were 38% for O-(Boc-Gly)-Cellulose, 29% for O-(Boc-Ala)-Cellulose and 53% for O-(Boc-β-Ala)-Cellulose. The one-by-one N-acylation between the O-(Xaa)-Celluloses and Boc-Ala-Gly using a water-soluble carbodiimide yielded the conjugates N-(Boc-Ala-Gly)-Xaa-Celluloses with DS%(/NH2) values of 25% (Xaa = Gly), 35% (Ala), and 48% (β-Ala), respectively. The results were well correlated with ΔG and ΔEstrain profiles, which were predicted by semi-empirical thermochemical parameter calculation coupled with conformer search (R(2)>0.90). N-acylation of the O-(β-Ala)-Cellulose using various length of oligo-peptides, Boc-(Ala-Gly)n and Boc-(Gly-Ala)n (where, n = 0.5, 1.0, 1.5, 2.0, 3.0), suggested that the DS%(/NH2) was dependent on the structural features of the symmetric anhydrides as the N-acylating agents, including conformer populations and their transition energy.

Synthesis of peptide-cellulose conjugate mediated by a soluble cellulose derivative having β-Ala esters

A derivatization of cellulose was investigated for gaining up the solubility for subsequent conjugation reaction. N(β)-Boc-β-Ala, was introduced to the parent cellulose using carbonyl diimidazole. Degree of substitution towards the cellulose hydroxyls was 49%. Subsequent removal of Boc in trifluoroacetic acid (TFA) yielded β-Ala-cellulose·TFA salt. A protected hexapeptide, Boc-Ser(Bzl)-Gly-Tyr(Bzl)-Ser(Bzl)-Gly-Lys(Z) was synthesized via 9 steps of peptide elongation, and the C-end carboxyl groups of the peptide was coupled with the β-Ala-cellulose in a homogenous dimethyl sulfoxide solution, using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide monohydrochloride to ensure the N(β)-selective acylation. The degree of substitution of the protected peptide towards the β-amino groups of β-Ala-cellulose (DS%(/NH(2))) was 52% for 1.0 eq.mol of the protected peptide feed, and in the presence of N-hydroxysuccinimide, DS%(/NH(2)) was increased to 61%. At 4.0 eq.mol feed, almost quantitative conjugation was observed as DS%(/NH(2))=98-99%. Deprotection of the conjugate using thioanisole-TFA resulted in complete removal of Boc, Bzl on Tyr, and Z on Lys, while a very trace amount of Bzl on Ser seemed to be left uncleaved.