3D MICROSIZED PROTEIN AMYLOID PARTICULATES AS EFFECTIVE BIOADSORBERS FOR Pb2+ IONS

The production of new cost-effective biocompatible sorbent sustainable materials, with natural origins, able to remove heavy metals from water resources is nowadays highly desirable in order to reduce pollution and increase clean water availability. In this context, self-assembled protein materials with highly ordered amyloid structures, stabilised by H-bonds, seems to have a great potential as natural platform for a broader development of highly-tunable structures. By suitably varying solution conditions it is possible to tune aggregate size, surface area and morphologies as well as their physicochemical (hydrophobicity, hydrophilicity, swelling/deswelling properties) and mechanical properties1. In this work we show how Bovine Serum Albumin (BSA) particulates2-3, a generic form of protein aggregates, with spherical microsized shape can be used as adsorbents of Pb2+ ions from aqueous solution4. We used spectroscopy and microscopy methods to characterize the aggregates formation, structure and morphologies. Inductively coupled plasma Optical Emission Spectroscopy (ICP – OES) and Differential Pulse Anodic Stripping Voltammetry (DP-ASV) techniques are used to evaluate uptake/release of metal ions in different conditions of pH, ionic medium, ionic strength, and temperature as a function of time and of adsorbate – adsorbent ratio in kinetic and thermodynamic experiments. The most used kinetic and isotherm equations were used to fit experimental data in order to obtain information about adsorption mechanism, which is the result of the balance of specific interactions with functional groups in protein structure and not specific ones common to all polypeptide chains, and possibly related to amyloid state and to modification of particulates hydration layer. Therefore, it is possible to highlight peculiar structural features essential for metal binding changing aggregation conditions and in turn molecular properties of aggregates. This knowledge may provide extraordinary opportunities towards the design and production of new tailorable bio sorbents using natural raw materials and which can also be exploited for several cycles of purification with minimal reduction in performance.