Annual review of chemical and biomolecular engineering最新文献

Alternative polymer feedstocks are highly desirable to address environmental, social, and security concerns associated with petrochemical-based materials. Lignocellulosic biomass (LCB) has emerged as one critical feedstock in this regard because it is an abundant and ubiquitous renewable resource. LCB can be deconstructed to generate valuable fuels, chemicals, and small molecules/oligomers that are amenable to modification and polymerization. However, the diversity of LCB complicates the evaluation of biorefinery concepts in areas including process scale-up, production outputs, plant economics, and life-cycle management. We discuss aspects of current LCB biorefinery research with a focus on the major process stages, including feedstock selection, fractionation/deconstruction, and characterization, along with product purification, functionalization, and polymerization to manufacture valuable macromolecular materials. We highlight opportunities to valorize underutilized and complex feedstocks, leverage advanced characterization techniques to predict and manage biorefinery outputs, and increase the fraction of biomass converted into valuable products.

Are deep eutectic solvents (DESs) a promising alternative to conventional solvents? Perhaps, but their development is hindered by a plethora of misconceptions. These are carefully analyzed here, beginning with the very meaning of DESs, which has strayed far beyond its original scope of eutectic mixtures of Lewis or Brønsted acids and bases. Instead, a definition that is grounded on thermodynamic principles and distinguishes between eutectic and deep eutectic is encouraged, and the types of precursors that can be used to prepare DESs are reviewed. Landmark works surrounding the sustainability, stability, toxicity, and biodegradability of these solvents are also discussed, revealing piling evidence that numerous DESs reported thus far, particularly those that are choline based, lack sufficient sustainability-related traits to be considered green solvents. Finally, emerging DES applications are reviewed, emphasizing their most remarkable feature: the ability to liquefy a solid compound with a target property, allowing its use as a liquid solvent.

Oxidative stress is an important and pervasive physical stress encountered by all kingdoms of life, including bacteria. In this review, we briefly describe the nature of oxidative stress, highlight well-characterized protein-based sensors (transcription factors) of reactive oxygen species that serve as standards for molecular sensors in oxidative stress, and describe molecular studies that have explored the potential of direct RNA sensitivity to oxidative stress. Finally, we describe the gaps in knowledge of RNA sensors-particularly regarding the chemical modification of RNA nucleobases. RNA sensors are poised to emerge as an essential layer of understanding and regulating dynamic biological pathways in oxidative stress responses in bacteria and, thus, also represent an important frontier of synthetic biology.

From the first clinical trial by Dr. W.F. Anderson to the most recent US Food and Drug Administration-approved Luxturna (Spark Therapeutics, 2017) and Zolgensma (Novartis, 2019), gene therapy has revamped thinking and practice around cancer treatment and improved survival rates for adult and pediatric patients with genetic diseases. A major challenge to advancing gene therapies for a broader array of applications lies in safely delivering nucleic acids to their intended sites of action. Peptides offer unique potential to improve nucleic acid delivery based on their versatile and tunable interactions with biomolecules and cells. Cell-penetrating peptides and intracellular targeting peptides have received particular focus due to their promise for improving the delivery of gene therapies into cells. We highlight key examples of peptide-assisted, targeted gene delivery to cancer-specific signatures involved in tumor growth and subcellular organelle-targeting peptides, as well as emerging strategies to enhance peptide stability and bioavailability that will support long-term implementation.

Electrochemical synthesis of organic chemical commodities provides an alternative to conventional thermochemical manufacturing and enables the direct use of renewable electricity to reduce greenhouse gas emissions from the chemical industry. We discuss electrochemical synthesis approaches that use abundant carbon feedstocks for the production of the largest petrochemical precursors and basic organic chemical products: light olefins, olefin oxidation derivatives, aromatics, and methanol. First, we identify feasible routes for the electrochemical production of each commodity while considering the reaction thermodynamics, available feedstocks, and competing thermochemical processes. Next, we summarize successful catalysis and reaction engineering approaches to overcome technological challenges that prevent electrochemical routes from operating at high production rates, selectivity, stability, and energy conversion efficiency. Finally, we provide an outlook on the strategies that must be implemented to achieve large-scale electrochemical manufacturing of major organic chemical commodities.

Drying drops of colloidal dispersions have attracted attention from researchers since the nineteenth century. The multiscale nature of the problem involving physics at different scales, namely colloidal and interfacial phenomena as well as heat, mass, and momentum transport processes, combined with the seemingly simple yet nontrivial shape of the drops makes drying drop problems rich and interesting. The scope of such studies widens as the physical and chemical nature of dispersed entities in the drop vary and as evaporation occurs in more complex configurations. This review summarizes past and contemporary developments in the field, emphasizing the physicochemical and hydrodynamical principles that govern the processes occurring within a drying drop and the resulting variety of patterns generated on the substrate.

Active colloids use energy input at the particle level to propel persistent motion and direct dynamic assemblies. We consider three types of colloids animated by chemical reactions, time-varying magnetic fields, and electric currents. For each type, we review the basic propulsion mechanisms at the particle level and discuss their consequences for collective behaviors in particle ensembles. These microscopic systems provide useful experimental models of nonequilibrium many-body physics in which dissipative currents break time-reversal symmetry. Freed from the constraints of thermodynamic equilibrium, active colloids assemble to form materials that move, reconfigure, heal, and adapt. Colloidal machines based on engineered particles and their assemblies provide a basis for mobile robots with increasing levels of autonomy. This review provides a conceptual framework for understanding and applying active colloids to create material systems that mimic the functions of living matter. We highlight opportunities for chemical engineers to contribute to this growing field.

In the past two decades, we have witnessed a rapid emergence of new and powerful photochemical and photocatalytic synthetic methods. Although these methods have been used mostly on a small scale, there is a growing need for efficient scale-up of photochemistry in the chemical industry. This review summarizes and contextualizes the advancements made in the past decade regarding the scale-up of photo-mediated synthetic transformations. Simple scale-up concepts and important fundamental photochemical laws have been provided along with a discussion concerning suitable reactor designs that should facilitate scale-up of this challenging class of organic reactions.