Diatom microalgae as smart nanocontainers for biosensing wastewater pollutants: recent trends and innovations

Abstract

Microalgae have been recognized as one of the most efficient microorganisms to remediate industrial effluents. Among microalgae diatoms are silica shelled unicellular eukaryotes, found in all types of water bodies and flourish very well even in wastewater. They have their silica cell wall made up of nano arrayed pores arranged in a uniform fashion. Therefore, they act as smart nanocontainers to adsorb various trace metals, dyes, polymers, and drugs which are hazardous to human as well to aquatic life. The beautiful nanoarchitecture in diatoms allows them to easily bind to ligands of choice to form a nanocomposite structure with the pollutants which can be a chemical or biological component. Such naturally available diatom nanomaterials are economical and highly sensitive compared to manmade artificial silica nanomaterials to help in facile removal of the toxic pollutants from wastewater. This review is thus focused on employing diatoms to remediate various pollutants such as heavy metals, dyes, hydrocarbons detected in the wastewater. It also includes different microalgae as biosensors for determination of pollutants in effluents and the perspectives for nanotechnological applications in the field of remediating pollutants through microalgae. The review also discusses in length the hurdles and perspectives of employing microalgae in wastewater remediation.

Diatom Biosilica in Targeted Drug Delivery and Biosensing Applications: Recent Studies

“…As a consequence, diatom biosilica has found wide applications in the fabrication of plasmonic devices in the fields of biochemical sensing, diagnostics and therapeutics. Numerous such examples have been described in the past [15,18,34,40,52], but within the constraints of this review, we highlight eight studies.…”

“…Increasing research interest in the exploitation of diatom biosilica comes from its varied 3D architecture currently unmatched by human engineering, mechanical and thermal inertness, relative straightforward chemical surface modifications, biocompatibility, stability, high specific surface area and regular pours structures. All these features have rendered diatoms very attractive as materials in a variety of applications, including wastewater treatment [17][18][19], bioremediation [19][20][21], tissue engineering [22,23] or catalysis [24]. The periodically nanostructured pore arrays of the diatoms, in particular, are responsible for the optical signal enhancement in fluorescence and Raman biosensing applications.…”

“…Indeed, several excellent reviews addressing the subjects prior to our selected timeframe are available to the reader [6][7][8][9][10][11][12][13][14][15]24]. More recently, other authors have also discussed different aspects of the fields in terms, e.g., of the applications of diatoms or microalgae in bio-sensing and -technology [18,[32][33][34], the discovery of active compounds [35][36][37], surface chemistry [38], material science [39][40][41] and as drug carries [42][43][44]. We begin with a short overview of the diatoms' structure and we then move specifically to the use of diatoms for the targeted delivery of anticancer and antibiotic drugs, and how the same microalgae are employed in the fabrications of biosensors whose analyte signal response is evaluated via fluorescence and surface-enhanced Raman scattering techniques.…”

A review on biofiltration techniques: recent advancements in the removal of volatile organic compounds and heavy metals in the treatment of polluted water

“…Maximum removal of heavy metals 80% was observed at a 1:1 ratio of carbon and sulfate for 126 days of treatment [ 195 ]. Very recent microalgae diatoms with silica shelled of eukaryotic cells were found its capacitance in the sensing of different pollutants present in wastewater [ 196 ]. The microalgae act in two ways with the perspective of nanotechnology: first to detect the pollutants and next to act as smart nanocontainers.…”

“…This was possible by the creation of bonding of nano-smart microalgae with the pollutants of choice of ligands. While compared to the artificial silica-based nanomaterials, the natural microalgae of nanosize are affordable in treating the pollutants [ 196 ]. So, microorganisms under suitable parameters could effectively capture heavy metals.…”