Amino-Acid-Encoded Bioinspired Supramolecular Self-Assembly of Multimorphological Nanocarriers.

Supramolecular self-assembly has emerged as an efficient tool to construct well-organized nanostructures for biomedical applications by small organic molecules. However, the physicochemical properties of self-assembled nanoarchitectures are greatly influenced by their morphologies, mechanical properties, and working mechanisms, making it challenging to design and screen ideal building blocks. Herein, using a biocompatible firefly-sourced click reaction between the cyano group of 2-cyano-benzothiazole (CBT) and the 1,2-aminothiol group of cysteine (Cys), an amino-acid-encoded supramolecular self-assembly platform Cys(SEt)-X-CBT (X represents any amino acid) is developed to incorporate both covalent and noncovalent interactions for building diverse morphologies of nanostructures with bioinspired response mechanism, providing a convenient and rapid strategy to construct site-specific nanocarriers for drug delivery, cell imaging, and enzyme encapsulation. Additionally, it is worth noting that the biodegradation of Cys(SEt)-X-CBT generated nanocarriers can be easily tracked via bioluminescence imaging. By caging either the thiol or amino groups in Cys with other stimulus-responsive sites and modifying X with probes or drugs, a variety of multi-morphological and multifunctional nanomedicines can be readily prepared for a wide range of biomedical applications.

A Simple Binary Supramolecular Co-Assembly Platform for Enhanced Tumor Imaging and Therapy.

The primary challenges in tumor imaging and therapy revolve around improving targeting efficiency, enhancing probe/drug delivery efficacy, and minimizing off-target signals and toxicity. Although various carriers have been developed, many are difficult to synthesize, costly, and not universally applicable. Furthermore, numerous carriers exhibit limited delivery rates in solid tumors, particularly larger nanocarriers. To address these challenges, a simple binary co-assembly drug delivery platform has been designed using the readily synthesized small molecule Cys(SEt)-Lys-CBT (CKCBT) as the self-assembly building block. CKCBT can effectively penetrate tumor cells due to its positively charged Lys side chain and small size. Upon glutathione reduction, CKCBT co-assembles with Nile red or Chlorin e6 to form nanofibers inside tumor cells. This enables their specific accumulation in tumor cells rather than normal cells and extends their exposure time, resulting in precise and enhanced tumor imaging and treatment. Hence, this uncomplicated and highly efficient binary co-assembly drug delivery platform can be easily adapted to a broad spectrum of probes and drugs, presenting a novel approach for advancing clinical diagnosis and therapy.

Amino-Acid-Encoded Supramolecular Nanostructures for Persistent Bioluminescence Imaging of Tumor.

Bioluminescence imaging (BLI) is a powerful technique for noninvasive monitoring of biological processes and cell transplantation. Nonetheless, the application of D-luciferin, which is widely employed as a bioluminescent probe, is restricted in long-term in vivo tracking due to its short half-life. This study presents a novel approach using amino acid-encoded building blocks to accumulate and preserve luciferin within tumor cells, through a supramolecular self-assembly strategy. The building block platform called Cys(SEt)-X-CBT (CXCBT, with X representing any amino acid) utilizes a covalent-noncovalent hybrid self-assembly mechanism to generate diverse luciferin-containing nanostructures in tumor cells after glutathione reduction. These nanostructures exhibit efficient tumor-targeted delivery as well as sequence-dependent well-designed morphologies and prolonged bioluminescence performance. Among the selected amino acids (X = Glu, Lys, Leu, Phe), Cys(SEt)-Lys-CBT (CKCBT) exhibits the superior long-lasting bioluminescence signal (up to 72 h) and good biocompatibility. This study demonstrates the potential of amino-acid-encoded supramolecular self-assembly as a convenient and effective method for developing BLI probes for long-term biological tracking and disease imaging.