Self-Assembly of Heterogeneous Ferritin Nanocages for Tumor Uptake and Penetration

Fusing fluorescent proteins and ferritin for protein cage based lighting devices

Ferritin cages are an effective platform to encapsulate and stabilize a range of active cargoes and present a promising stepping stone towards a wide range of applications. They have been explored for optoelectronic applications in combination with fluorescent proteins towards bio-hybrid light-emitting diodes (Bio-HLEDs) only recently. However, protein integration within the cage or coassembled ferritin cages relies on electrostatic interactions and requires the supercharging of the fluorescent protein that easily compromises functionality and stability. To address this limitation, we have developed a fusion protein combining the Thermotoga maritima apoferritin (TmaFt) with a green fluorescent protein named mGreenlantern (mGL). This approach avoids jeopardizing both the cage assembly capability of TmaFt and the photophysical features of mGL. After optimizing the fusion protein mGL-TmaFt with respect to the linker length, assembling efficiency, and mGL payload into the cage (mGL@TmaFt), our findings reveal that they exhibited enhanced thermal and structural stabilities in both solution and when embedded into a polymer matrix. This enables effective mGL shielding, reducing H-transfer deactivation of the chromophore and water-assisted heat transfer across the polymer network. Indeed, the photo-induced heat generation in Bio-HLEDs operating at high currents was significantly reduced, resulting in a 30- and 15-fold higher device stability compared to references with either mGL or mGL-TmaFt proteins, respectively. Overall, this work sets in the potential of protein cage design for photon manipulation in protein lighting devices.

Unveiling Structural Heterogeneity and Evolutionary Adaptations of Heteromultimeric Bacterioferritin Nanocages

Iron-storage bacterioferritins (Bfrs), existing in either homo- or hetero-multimeric form, play a crucial role in iron homeostasis. While the structure and function of homo-multimeric bacterioferritins (homo-Bfrs) have been extensively studied, little is known about the assembly, distinctive characteristics, or evolutionary adaptations of hetero-multimeric bacterioferritins (hetero-Bfrs). Here, the cryo-EM structure and functional characterization of a bacterial hetero-Bfr (SoBfr12) are reported. Compared to homo-Bfrs, although SoBfr12 exhibits a conserved spherical cage-like dodecahedron, its pores through which ions traverse exhibit substantially increased diversity. Importantly, the heterogeneity has significant impacts on sites for ion entry, iron oxidation, and reduction. Moreover, evolutionary analyses reveal that hetero-Bfrs may represent a new class within the Bfr subfamily, consisting of two different types that may have evolved from homo-Bfr through tandem duplication and directly from ferritin (Ftn) via dispersed duplication, respectively. These results reveal remarkable structural and functional features of a hetero-Bfr, enabling the rational design of nanocages for enhanced iron-storing efficiency and for other specific purposes, such as drug delivery vehicles and nanozymes.

SynBioNanoDesign: pioneering targeted drug delivery with engineered nanomaterials

Synthetic biology and nanotechnology fusion represent a transformative approach promoting fundamental and clinical biomedical science development. In SynBioNanoDesign, biological systems are reimagined as dynamic and programmable materials to yield engineered nanomaterials with emerging and specific functionalities. This review elucidates a comprehensive examination of synthetic biology's pivotal role in advancing engineered nanomaterials for targeted drug delivery systems. It begins with exploring the fundamental synergy between synthetic biology and nanotechnology, then highlights the current landscape of nanomaterials in targeted drug delivery applications. Subsequently, the review discusses the design of novel nanomaterials informed by biological principles, focusing on expounding the synthetic biology tools and the potential for developing advanced nanomaterials. Afterward, the research advances of innovative materials design through synthetic biology were systematically summarized, emphasizing the integration of genetic circuitry to program nanomaterial responses. Furthermore, the challenges, current weaknesses and opportunities, prospective directions, and ethical and societal implications of SynBioNanoDesign in drug delivery are elucidated. Finally, the review summarizes the transformative impact that synthetic biology may have on drug-delivery technologies in the future.

Rational Design of Dual-Targeted Nanomedicines for Enhanced Vascular Permeability in Low-Permeability Tumors

Designing dual-targeted nanomedicines to enhance tumor delivery efficacy is a complex challenge, largely due to the barrier posed by blood vessels during systemic delivery. Effective transport across endothelial cells is, therefore, a critical topic of study. Herein, we present a synthetic biology-based approach to engineer dual-targeted ferritin nanocages (Dt-FTn) for understanding receptor-mediated transport across tumor endothelial cells. By leveraging a genetically engineered logic-gated strategy, we coassembled various Dt-FTn in E. coli with tunable ratios of RGD-targeting and intrinsic TfR1-targeting ligands. These Dt-FTn constructs were employed to investigate the interaction between receptor-mediated vascular permeability and dual-targeted nanomedicines in low-permeability tumors. Through machine learning-based single vessel analysis, we uncovered the crucial role of dual-receptor expression profiles in determining the vascular transport of dual-targeted nanomedicines in tumors with low permeability. Using a patient-derived colon cancer model, we demonstrated a proof-of-concept that the optimal proportions of dual ligands in these nanomedicines can be customized based on tumor cell receptor expression profiles. This study provides valuable insights and guiding principles for the rational design of dual-targeted nanomedicines for tumor-targeted delivery.

Rational Design of Genetically Engineered Mitochondrial-Targeting Nanozymes for Alleviating Myocardial Ischemic-Reperfusion Injury

The development of mitochondria-targeting nanozymes holds significant promise for treating myocardial ischemia-reperfusion (IR) injury but faces significant biological barriers. To overcome these obstacles, we herein utilized genetically engineered ferritin nanocages (i.e., imFTn) to develop mitochondria-targeting nanozymes consisting of three ferritin subunit assembly modules: an IR-injured cardiomyocyte-targeting module, a lysosome-escaping module, and a mitochondria-targeting module. Using imFTn as a nanozyme platform, we developed nanozymes capable of efficiently catalyzing the l-Arg substrate to produce NO. The imFTn-Ru exhibits NO-generating activities, reduces mitochondrial reactive oxygen species generation, inhibits mitochondrial permeability transition pore opening, and enhances mitochondrial membrane potential. Furthermore, imFTn-Ru provides synergistic effects by specifically targeting myocardial IR-injured tissues, facilitating their accumulation in mitochondria, and protecting mitochondria against myocardial IR-induced injury in both in vitro and in vivo models. This study underscores a rational approach to designing nanozymes for targeting specific subcellular organelles in the treatment of IR injury.

A Purely Biomanufactured System for Delivering Nanoparticles and STING Agonists

Nanovaccines have significantly contributed in the prevention and treatment of diseases. However, most of these technologies rely on chemical or hybrid semibiological synthesis methods, which limit the manufacturing performance advantages and improved inoculation outcomes compared with traditional vaccines. Herein, a universal and purely biological nanovaccine system is reported. This system integrates three modules: (1) self-assembling nanoparticles, (2) self-catalyzed synthesis of small-molecule stimulator of interferon gene (STING) agonists, and (3) delivery vectors that target the cytosolic surveillance system. Various nanoparticles are efficiently self-assembled using this system. After confirming the excellent immunostimulatory and lymph node targeting of this system, its broad-spectrum antiviral efficacy is further demonstrated. By leveraging the comprehensive biosynthetic capabilities of bacterial cells, this system can efficiently combine various adjuvant-active modular components and antigenic cargo, thereby providing a highly diversified and potent vaccine platform.