Attaching palladium catalysts to antibodies

In Vivo Synthetic Anticancer Approach by Resourcing Mouse Blood Albumin as a Biocompatible Artificial Metalloenzyme

Methods for producing drugs directly at the cancer site, particularly using bioorthogonal metal catalysts, are being explored to mitigate the side effects of therapy. Albumin-based artificial metalloenzymes (ArMs) catalyze reactions in living mice while protecting the catalyst in the hydrophobic pocket. Here, we describe the in situ preparation and application of biocompatible tumor-targeting ArMs using circulating albumin, which is abundant in the bloodstream. The ArM was formed using blood albumin through the intravenous injection of ruthenium conjugated with an albumin-binding ligand; the tumor-targeting unit was conjugated to the ArM using its catalytic activity, and the ArM was transported to the cancer site. The delivered ArM catalyzed a second tagging reaction of the proapoptotic peptide on the cancer surface, successfully suppressing cancer proliferation. This approach, which efficiently leveraged the persisting reactivity twice in vivo, holds promise for future in vivo metal-catalyzed drug synthesis utilizing endogenous albumin.

Target-Specific Bioorthogonal Reactions for Precise Biomedical Applications

Bioorthogonal chemistry is a promising toolbox for dissecting biological processes in the native environment. Recently, bioorthogonal reactions have attracted considerable attention in the medical field for treating diseases, since this approach may lead to improved drug efficacy and reduced side effects via in situ drug synthesis. For precise biomedical applications, it is a prerequisite that the reactions should occur in the right locations and on the appropriate therapeutic targets. In this minireview, we highlight the design and development of targeted bioorthogonal reactions for precise medical treatment. First, we compile recent strategies for achieving target-specific bioorthogonal reactions. Further, we emphasize their application for the precise treatment of different therapeutic targets. Finally, a perspective is provided on the challenges and future directions of this emerging field for safe, efficient, and translatable disease treatment.

Palladium responsive liposomes for triggered release of aqueous contents

Palladium (Pd) is a promising metal catalyst for novel bioorthogonal chemistry and prodrug activation. This report describes the first example of palladium responsive liposomes. The key molecule is a new caged phospholipid called Alloc-PE that forms stable liposomes (large unilamellar vesicles, ∼220 nm diameter). Liposome treatment with PdCl2 removes the chemical cage, liberates membrane destabilizing dioleoylphosphoethanolamine (DOPE), and triggers liposome leakage of encapsulated aqueous contents. The results indicate a path towards liposomal drug delivery technologies that exploit transition metal triggered leakage.