Lead sulfide quantum dots inside ferritin: synthesis and application to photovoltaics

Ferritin: A Promising Nanoreactor and Nanocarrier for Bionanotechnology

The essence of bionanotechnology lies in the application of nanotechnology/nanomaterials to solve the biological problems. Quantum dots and nanoparticles hold potential biomedical applications, but their inherent problems such as low solubility and associated toxicity due to their interactions at nonspecific target sites is a major concern. The self-assembled, thermostable, ferritin protein nanocages possessing natural iron scavenging ability have emerged as a potential solution to all the above-mentioned problems by acting as nanoreactor and nanocarrier. Ferritins, the cellular iron repositories, are hollow, spherical, symmetric multimeric protein nanocages, which sequester the excess of free Fe(II) and synthesize iron biominerals (Fe₂O₃·H₂O) inside their ∼5-8 nm central cavity. The electrostatics and dynamics of the pore residues not only drives the natural substrate Fe²⁺ inside ferritin nanocages but also uptakes a set of other metals ions/counterions during in vitro synthesis of nanomaterial. The current review aims to report the recent developments/understanding on ferritin structure (self-assembly, surface/pores electrostatics, metal ion binding sites) and chemistry occurring inside these supramolecular protein cages (protein mediated metal ion uptake and mineralization/nanoparticle formation) along with its surface modification to exploit them for various nanobiotechnological applications. Furthermore, a better understanding of ferritin self-assembly would be highly useful for optimizing the incorporation of nanomaterials via the disassembly/reassembly approach. Several studies have reported the successful engineering of these ferritin protein nanocages in order to utilize them as potential nanoreactor for synthesizing/incorporating nanoparticles and as nanocarrier for delivering imaging agents/drugs at cell specific target sites. Therefore, the combination of nanoscience (nanomaterials) and bioscience (ferritin protein) projects several benefits for various applications ranging from electronics to medicine.

Recent Developments of Solar Cells from PbS Colloidal Quantum Dots

PbS (lead sulfide) colloidal quantum dots consist of crystallites with diameters in the nanometer range with organic molecules on their surfaces, partly with additional metal complexes as ligands. These surface molecules are responsible for solubility and prevent aggregation, but the interface between semiconductor quantum dots and ligands also influences the electronic structure. PbS quantum dots are especially interesting for optoelectronic applications and spectroscopic techniques, including photoluminescence, photodiodes and solar cells. Here we concentrate on the latter, giving an overview of the optical properties of solar cells prepared with PbS colloidal quantum dots, produced by different methods and combined with diverse other materials, to reach high efficiencies and fill factors.

Supramolecular protein polymers using mini-ferritin Dps as the building block

Production of long polymer chains with iron oxidation and storage activity, built from protein nanocages using a click chemistry approach.