Engineered Protein-Iron Oxide Hybrid Biomaterial for MRI-traceable Drug Encapsulation

Coiled-Coil Protein Hydrogels Engineered with Minimized Fiber Diameters for Sustained Release of Doxorubicin in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) lacks expressed protein targets, making therapy development challenging. Hydrogels offer a promising new route in this regard by improving the chemotherapeutic efficacy through increased solubility and sustained release. Moreover, subcutaneous hydrogel administration reduces patient burden by requiring less therapy and shorter treatment times. We recently established the design principles for the supramolecular assembly of single-domain coiled-coils into hydrogels. Using a modified computational design algorithm, we designed Q8, a hydrogel with rapid assembly for faster therapeutic hydrogel preparation. Q8 encapsulates and releases doxorubicin (Dox), enabling localized sustained release via subcutaneous injection. Remarkably, a single subcutaneous injection of Dox-laden Q8 (Q8•Dox) significantly suppresses tumors within just 1 week. This work showcases the bottom-up engineering of a fully protein-based drug delivery vehicle for improved TBNC treatment via noninvasive localized therapy.

Protein-Engineered Fibers For Drug Encapsulation Traceable via 19F Magnetic Resonance

Theranostic materials research is experiencing rapid growth driven by the interest in integrating both therapeutic and diagnostic modalities. These materials offer the unique capability to not only provide treatment but also track the progression of a disease. However, to create an ideal theranostic biomaterial without compromising drug encapsulation, diagnostic imaging must be optimized for improved sensitivity and spatial localization. Herein, we create a protein-engineered fluorinated coiled-coil fiber, Q2TFL, capable of improved sensitivity to 19F magnetic resonance spectroscopy (MRS) detection. Leveraging residue-specific noncanonical amino acid incorporation of trifluoroleucine (TFL) into the coiled-coil, Q2, which self-assembles into nanofibers, we generate Q2TFL. We demonstrate that fluorination results in a greater increase in thermostability and 19F magnetic resonance detection compared to the nonfluorinated parent, Q2. Q2TFL also exhibits linear ratiometric 19F MRS thermoresponsiveness, allowing it to act as a temperature probe. Furthermore, we explore the ability of Q2TFL to encapsulate the anti-inflammatory small molecule, curcumin (CCM), and its impact on the coiled-coil structure. Q2TFL also provides hyposignal contrast in 1H MRI, echogenic signal with high-frequency ultrasound and sensitive detection by 19F MRS in vivo illustrating fluorination of coiled-coils for supramolecular assembly and their use with 1H MRI, 19F MRS and high frequency ultrasound as multimodal theranostic agents.

Supramolecular Assembly and Small-Molecule Binding by Protein-Engineered Coiled-Coil Fibers

The ability to engineer a solvent-exposed surface of self-assembling coiled coils allows one to achieve a higher-order hierarchical assembly such as nano- or microfibers. Currently, these materials are being developed for a range of biomedical applications, including drug delivery systems; however, ways to mechanistically optimize the coiled-coil structure for drug binding are yet to be explored. Our laboratory has previously leveraged the functional properties of the naturally occurring cartilage oligomeric matrix protein coiled coil (C), not only for its favorable motif but also for the presence of a hydrophobic pore to allow for small-molecule binding. This includes the development of Q, a rationally designed pentameric coiled coil derived from C. Here, we present a small library of protein microfibers derived from the parent sequences of C and Q bearing various electrostatic potentials with the aim to investigate the influence of higher-order assembly and encapsulation of candidate small molecule, curcumin. The supramolecular fiber size appears to be well-controlled by sequence-imbued electrostatic surface potential, and protein stability upon curcumin binding is well correlated to relative structure loss, which can be predicted by in silico docking.