Biocatalysis has emerged as one of the most promising technologies to enable green synthesis of important chemicals, due to the ambient conditions generally applied for these reactions. Nonetheless, a general uptake of enzymatic transformations has been hindered by the perceived high cost of recombinant proteins. Recent interest in continuous flow from the synthetic chemistry community has now begun to spread to biotransformations, with protein immobilization playing a key part. As a consequence, continuous biotransformations using immobilized enzymes are becoming more accessible to nonexperts. This review will discuss several recent examples of continuous biotransformations that use immobilization, with a focus on examples involving fine chemical synthesis. It will also examine some of the issues that the community has as a whole, most importantly a lack of unified reporting tools to allow comparison and assessment of the different techniques.
Getting in shape: DNA‐brush copolymer amphiphiles assemble into micelles with morphologies determined by selective interactions that allow manipulation of the magnitude of steric and electrostatic repulsions in the micelle shells. Cylinder‐to‐sphere phase transitions occur when an input DNA sequence is added to the micelles (see picture).
In this Communication, we describe an enzyme-responsive, paclitaxel-loaded nanoparticle and assess its safety and efficacy in vivo in a human fibrosarcoma murine xenograft. The material was generated via graft-through block copolymerization of norbornene monomers with hydrophilic targeting peptides together with hydrophobic paclitaxel prodrugs. This work represents a proof-of-concept study demonstrating the utility of enzyme-responsive nanoscale drug carriers capable of targeted accumulation and retention in tumor tissue in response to overexpressed endogenous enzymes. Critically, we observed low systemic toxicity in healthy mice following intravenous administration, with the maximum tolerated dose (MTD) exceeding 240 mg/kg with respect to paclitaxel. Furthermore, we observed efficacy against tumorigenesis paralleling that of paclitaxel at equivalent intravenous dosing, and near complete tumor growth suppression when administered intratumorally. This work represents a significant departure from traditional targeted drug delivery systems and presents a new avenue of exploration for nanomedicine.
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