ABSTRACT
Dynamic covalent chemistry is a versatile and powerful tool that integrates both stable chemical bonds and stimulus responsiveness into the construction of smart biotherapeutics. With minimalistic molecular design, a dynamic covalent protein assembly that incorporates selective targeting and intracellular release upon pH stimulus is presented. The construct comprises an active enzymatic protein core (cytochrome c) self-assembled with cancer cell targeting motifs (somatostatin) through boronic acid/salicylhydroxamate chemistry. The bioorthogonal assembly takes place rapidly under neutral aqueous conditions while the release of the protein is initiated under acidic conditions found within cellular vesicles during uptake. By demonstrating that these modular components act in synergy, we show the broad applicability of such chemical strategies to advance the frontier of modern nanomedicine.
Subject(s)
Boronic Acids/chemistry , Cytochromes c/metabolism , Salicylamides/chemistry , Somatostatin/metabolism , A549 Cells , Calcium/metabolism , Cytochromes c/chemistry , Fluorescence Resonance Energy Transfer , Fluorescent Dyes/chemistry , Humans , Hydrogen-Ion Concentration , Microscopy, Confocal , Nanomedicine , Somatostatin/chemistryABSTRACT
The development of small protein tags that exhibit bioorthogonality, bond stability, and reversibility, as well as biocompatibility, holds great promise for applications in cellular environments enabling controlled drug delivery or for the construction of dynamic protein complexes in biological environments. Herein, we report the first application of dynamic covalent chemistry both for purification and for reversible assembly of protein conjugates using interactions of boronic acid with diols and salicylhydroxamates. Incorporation of the boronic acid (BA) tag was performed in a site-selective fashion by applying disulfide rebridging strategy. As an example, a model protein enzyme (lysozyme) was modified with the BA tag and purified using carbohydrate-based column chromatography. Subsequent dynamic covalent "click-like" bioconjugation with a salicylhydroxamate modified fluorescent dye (BODIPY FL) was accomplished while retaining its original enzymatic activity.
Subject(s)
Boronic Acids/chemistry , Click Chemistry , Proteins/chemistry , Boron Compounds/chemistry , Chromatography, Liquid/methods , Disulfides/chemistry , Fluorescent Dyes/chemistry , Muramidase/chemistry , Muramidase/metabolism , Proteins/isolation & purification , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Tandem Mass Spectrometry/methodsABSTRACT
The interaction of boronic acids with various bifunctional reagents offers great potential for the preparation of responsive supramolecular architectures. Boronic acids react with 1,2-diols yielding cyclic boronate esters that are stable at pH>7.4 but can be hydrolyzed at pH<5.0. The phenylboronic acid (PBA)-salicylhydroxamic acid (SHA) system offers ultra-fast reaction kinetics and high binding affinities. This Focus Review summarizes the current advances in exploiting the bioorthogonal interaction of boronic acids to build pH-responsive supramolecular architectures in water.
