Enzymes, In Vivo Biocatalysis, and Metabolic Engineering for Enabling a Circular Economy and Sustainability.

Since the industrial revolution, the rapid growth and development of global industries have depended largely upon the utilization of coal-derived chemicals, and more recently, the utilization of petroleum-based chemicals. These developments have followed a linear economy model (produce, consume, and dispose). As the world is facing a serious threat from the climate change crisis, a more sustainable solution for manufacturing, i.e., circular economy in which waste from the same or different industries can be used as feedstocks or resources for production offers an attractive industrial/business model. In nature, biological systems, i.e., microorganisms routinely use their enzymes and metabolic pathways to convert organic and inorganic wastes to synthesize biochemicals and energy required for their growth. Therefore, an understanding of how selected enzymes convert biobased feedstocks into special (bio)chemicals serves as an important basis from which to build on for applications in biocatalysis, metabolic engineering, and synthetic biology to enable biobased processes that are greener and cleaner for the environment. This review article highlights the current state of knowledge regarding the enzymatic reactions used in converting biobased wastes (lignocellulosic biomass, sugar, phenolic acid, triglyceride, fatty acid, and glycerol) and greenhouse gases (CO2 and CH4) into value-added products and discusses the current progress made in their metabolic engineering. The commercial aspects and life cycle assessment of products from enzymatic and metabolic engineering are also discussed. Continued development in the field of metabolic engineering would offer diversified solutions which are sustainable and renewable for manufacturing valuable chemicals.

Antibiotics armed neutrophils as a potential therapy for brain fungal infection caused by chemotherapy-induced neutropenia.

Chemotherapy-induced neutropenia, a symptom of neutrophil depletion, makes cancer patients highly susceptible to invasive fungal infection with substantial morbidity and mortality. To address the cryptococcal brain infection in this condition, this study attempts to arm neutrophils (NEs) with antibiotics to potentiate the antifungal capability of NEs. To allow effective integration, amphotericin B, a potent antibiotic, is assembled with albumin nanoparticles through hydrophobic and hydrogen-bond interactions to form AmB@BSA nanoparticles (A-NPs). The nutrient composition (albumin) and virus-like size (~40 nm) facilitate efficient uptake of A-NPs by NEs to construct the antibiotics-armed NEs. It is demonstrated that the armed NEs can maintain the intrinsic biological functions of NEs, such as cell viability and capacity of migration to an inflammatory site. In a neutropenic mouse model of brain fungal infection, the treatment with the armed NEs allows for preventing fungal invasion more effectively than that with the native NEs, without the apparent systemic toxicity. Such a synergistic anti-infection system maximizes the antifungal effects by taking advantage of NEs and antibiotics. It provides a potential NEs-mediated therapeutic approach for treating fungal infection caused by chemotherapy-induced neutropenia.

Bioengineering of nano metal-organic frameworks for cancer immunotherapy.

Immunotherapy techniques, such as immune checkpoint inhibitors, chimeric antigen receptor (CAR) T cell therapies and cancer vaccines, have been burgeoning with great success, particularly for specific cancer types. However, side effects with fatal risks, dysfunction in tumor microenvironment and low immune response rates remain the bottlenecks in immunotherapy. Nano metal-organic frameworks (nMOFs), with an accurate structure and a narrow size distribution, are emerging as a solution to these problems. In addition to their function of temporospatial delivery, a large library of their compositions, together with flexibility in chemical interaction and inherent immune efficacy, offers opportunities for various designs of nMOFs for immunotherapy. In this review, we overview state-of-the-art research on nMOFs-based immunotherapies as well as their combination with other therapies. We demonstrate that nMOFs are predominantly customized for vaccine delivery or tumor-microenvironment modulation. Finally, a prospect of nMOFs in cancer immunotherapy will be discussed.

In-Line Purification: A Key Component to Facilitate Drug Synthesis and Process Development in Medicinal Chemistry.

In-line purification is an important tool for flow chemistry. It enables effective handling of unstable intermediates and integration of multiple synthetic steps. The integrated flow synthesis is useful for drug synthesis and process development in medicinal chemistry. In this article, we overview current states of in-line purification methods. In particular, we focus on four common methods: scavenger column, distillation, nanofiltration, and extraction. Examples of their applications are provided.

Cell membrane biomimetic nanoparticles for inflammation and cancer targeting in drug delivery.

Nanoparticle capture and elimination by the immune system are great obstacles for drug delivery. Camouflaging nanoparticles with cell membrane represents a promising strategy to communicate and negotiate with the immune system. As a novel class of nanotherapeutics, such biomimetic nanoparticles inherit specific biological functionalities of the source cells (e.g., erythrocytes, immune cells, cancer cells and platelets) in order to evade immune elimination, prolong circulation time, and even target a disease region by virtue of the homing tendency of the cell membrane protein. In this review, we begin with an overview of different cell membranes that can be utilized to create a biointerface on nanoparticles. Subsequently, we elaborate on the state-of-the-art of cell membrane biomimetic nanoparticles for drug delivery. In particular, a summary of data on circulation capacity and targeting efficiency by camouflaged nanoparticles is presented. In addition to cancer therapy, inflammation treatment, as an emerging application of biomimetic nanoparticles, is specifically included. The challenges and outlook of this technology are discussed.

Perspectives on the Use of Liquid Extraction for Radioisotope Purification.

The reliable and efficient production of radioisotopes for diagnosis and therapy is becoming an increasingly important capability, due to their demonstrated utility in Nuclear Medicine applications. Starting from the first processes involving the separation of 99mTc from irradiated materials, several methods and concepts have been developed to selectively extract the radioisotopes of interest. Even though the initial methods were based on liquid-liquid extraction (LLE) approaches, the perceived difficulty in automating such processes has slowly moved the focus towards resin separation methods, whose basic chemical principles are often similar to the LLE ones in terms of chelators and phases. However, the emerging field of flow chemistry allows LLE to be easily automated and operated in a continuous manner, resulting in an even improved efficiency and reliability. In this contribution, we will outline the fundamentals of LLE processes and their translation into flow-based apparatuses; in addition, we will provide examples of radioisotope separations that have been achieved using LLE methods. This article is intended to offer insights about the future potential of LLE to purify medically relevant radioisotopes.

Advanced Continuous Flow Platform for On-Demand Pharmaceutical Manufacturing.

As a demonstration of an alternative to the challenges faced with batch pharmaceutical manufacturing including the large production footprint and lengthy time-scale, we previously reported a refrigerator-sized continuous flow system for the on-demand production of essential medicines. Building on this technology, herein we report a second-generation, reconfigurable and 25 % smaller (by volume) continuous flow pharmaceutical manufacturing platform featuring advances in reaction and purification equipment. Consisting of two compact [0.7 (L)×0.5 (D)×1.3 m (H)] stand-alone units for synthesis and purification/formulation processes, the capabilities of this automated system are demonstrated with the synthesis of nicardipine hydrochloride and the production of concentrated liquid doses of ciprofloxacin hydrochloride, neostigmine methylsulfate and rufinamide that meet US Pharmacopeia standards.

Multistage extraction platform for highly efficient and fully continuous purification of nanoparticles.

This paper presents a fully-continuous novel liquid-liquid-extraction (LLE) platform for the purification of nanoparticles. The use of multistage operation enhances the purity of the final stream without the expense of high solvent consumption. Two case studies, purification of CdSe quantum dots in organic solvent and that of gold nanoparticles in water, demonstrate that the LLE platform is versatile, non-destructive, and highly efficient.

On-demand continuous-flow production of pharmaceuticals in a compact, reconfigurable system.

Pharmaceutical manufacturing typically uses batch processing at multiple locations. Disadvantages of this approach include long production times and the potential for supply chain disruptions. As a preliminary demonstration of an alternative approach, we report here the continuous-flow synthesis and formulation of active pharmaceutical ingredients in a compact, reconfigurable manufacturing platform. Continuous end-to-end synthesis in the refrigerator-sized [1.0 meter (width) × 0.7 meter (length) × 1.8 meter (height)] system produces sufficient quantities per day to supply hundreds to thousands of oral or topical liquid doses of diphenhydramine hydrochloride, lidocaine hydrochloride, diazepam, and fluoxetine hydrochloride that meet U.S. Pharmacopeia standards. Underlying this flexible plug-and-play approach are substantial enabling advances in continuous-flow synthesis, complex multistep sequence telescoping, reaction engineering equipment, and real-time formulation.