Microbial Pigments: Major Groups and Industrial Applications

Microbial pigments have many structures and functions with excellent characteristics, such as being biodegradable, non-toxic, and ecologically friendly, constituting an important source of pigments. Industrial production presents a bottleneck in production cost that restricts large-scale commercialization. However, microbial pigments are progressively gaining popularity because of their health advantages. The development of metabolic engineering and cost reduction of the bioprocess using industry by-products opened possibilities for cost and quality improvements in all production phases. We are thus addressing several points related to microbial pigments, including the major classes and structures found, the advantages of use, the biotechnological applications in different industrial sectors, their characteristics, and their impacts on the environment and society.

Hydrogen Bonding Nanoarchitectonics of Organic Pigment-Based Janus Microrobots with Entering Capability into Cancer Cells

Autonomous microrobots are at the forefront of biomedical research as they are expected to be applied for specific tasks at the intracellular level such as cargo delivery, sensing, molecular manipulation, among others. Here, we report on a preparation of microrobots based on quinacridone and indigo, which are members of the organic hydrogen-bonded pigment family. The microrobots were fabricated by asymmetric platinum deposition on corresponding quinacridone and indigo microparticles that possessed a homogeneous size and shape distribution. The microrobots exhibited autonomous locomotion in the presence of hydrogen peroxide, which was further supported by UV irradiation. The organic pigment-based microrobots were studied in the presence of mouse colorectal carcinoma cells, and it was observed that they were internalized into the cells. Internalization was visualized using confocal laser scanning microscopy. This study reveals the possibility of fabricating hydrogen-bonded organic pigment-based microrobots for biomedical applications by employing the principles of nanoarchitectonics.

A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems

Through a modern derivation of Planck’s formula for the entropy of an arbitrary beam of photons, we derive a general expression for entropy production due to the irreversible process of the absorption of an arbitrary incident photon spectrum in material and its dissipation into an infrared-shifted grey-body emitted spectrum, with the rest being reflected or transmitted. Employing the framework of Classical Irreversible Thermodynamic theory, we define the generalized thermodynamic flow as the flow of photons from the incident beam into the material and the generalized thermodynamic force is, then, the entropy production divided by the photon flow, which is the entropy production per unit photon at a given wavelength. We compare the entropy production of different inorganic and organic materials (water, desert, leaves and forests) under sunlight and show that organic materials are the greater entropy-producing materials. Intriguingly, plant and phytoplankton pigments (including chlorophyll) reach peak absorption exactly where entropy production through photon dissipation is maximal for our solar spectrum 430<λ<550 nm, while photosynthetic efficiency is maximal between 600 and 700 nm. These results suggest that the evolution of pigments, plants and ecosystems has been towards optimizing entropy production, rather than photosynthesis. We propose using the wavelength dependence of global entropy production as a biosignature for discovering life on planets of other stars.

Direct electrochemical capture and release of carbon dioxide using an industrial organic pigment: quinacridone

Limiting anthropogenic carbon dioxide emissions constitutes a major issue faced by scientists today. Herein we report an efficient way of controlled capture and release of carbon dioxide using nature inspired, cheap, abundant and non-toxic, industrial pigment namely, quinacridone. An electrochemically reduced electrode consisting of a quinacridone thin film (ca. 100 nm thick) on an ITO support forms a quinacridone carbonate salt. The captured CO2 can be released by electrochemical oxidation. The amount of captured CO2 was quantified by FT-IR. The uptake value for electrochemical release process was 4.61 mmol g(-1). This value is among the highest reported uptake efficiencies for electrochemical CO2 capture. For comparison, the state-of-the-art aqueous amine industrial capture process has an uptake efficiency of ca. 8 mmol g(-1).