Protein@Inorganic Nanodumpling System for High-Loading Protein Delivery with Activatable Fluorescence and Magnetic Resonance Bimodal Imaging Capabilities

Abstract

Efficient protein delivery into the target cell is highly desirable for protein therapeutics. Current approaches for protein delivery commonly suffer from low-loading protein capacity, poor specificity for target cells, and invisible protein release. Herein, we report a protein@inorganic nanodumpling (ND) system as an intracellular protein delivery platform. Similar to a traditional Chinese food, the dumpling, ND consists of a protein complex “filling” formed by metal-ion-directed self-assembly of protein cargos fused to histidine-rich green fluorescent proteins (H39GFPs), which are further encapsulated by an external surface “wrapper” of manganese dioxide (MnO2) via in situ biomineralization. This ND structure allows for a high loading capacity (>63 wt %) for protein cargos with enhanced stability. NDs can be targeted and internalized into cancer cells specifically through folic acid receptors by surface-tailored folic acid. The protein cargo release is in a bistimuli-responsive manner, triggered by an either reductive or acidic intracellular microenvironment. Moreover, the MnO2 nanowrapper is an efficient fluorescence quencher for inner fused GFPs and also a “switch-on” magnetic resonance imaging (MRI) agent via triggered release of Mn2+ ions, which enables activatable fluorescence/MRI bimodal imaging of protein release. Finally, the ND is highly potent and specific to deliver functional protein ribonuclease A (RNase A) into cultured target cells and the tumor site in a xenografted mouse model, eliminating the tumor cells with high therapeutic efficacy. Our approach provides a promising alternative to advance protein-based cancer therapeutics.

Biomineralization: An Opportunity and Challenge of Nanoparticle Drug Delivery Systems for Cancer Therapy

“…Therefore, the most recent studies were still based on dual‐stimuli‐responsive release. [ 40 ] Li et al. prepared a hybrid nanosphere with pH and GSH dual‐stimuli response in a one‐pot method.…”

“…[ 100 ] This strategy is an effective and green approach. The inorganic nanoparticles (e.g., Au nanoclusters, [ 101 ] Ag 2 S quantum dots, [ 102 ] and MnO 2 nanoparticles [ 40a ] ) and hybrid nanoparticles (e.g., Gd/CuS, [ 103 ] Gd/Au, [ 104 ] and Mn/Au [ 105 ] ) based on protein biomimetic mineralization have excellent biocompatibility, good stability, rich surface functional groups, and high water solubility. However, the process of biomineralization may affect the enzymatic activity or targeting of some proteins, which limits the use of proteins as a template for biomineralization.…”

Internally Responsive Nanomaterials for Activatable Multimodal Imaging of Cancer

“…for biothiol and pH activatable FL and MR imaging using a green and straightforward process (Figure 10d). [ 88 ] In their design, functional proteins were fused with a 39‐histidine base‐green fluorescent protein (H 39 GFP) tag to enable zinc ion directed self‐assembly as the “filling.” The fabricated protein complex was then coated using in situ biomineralization with a MnO 2 “wrapper” and then PEGylated with a FA‐containing moiety for enhanced circulation and biocompatibility as well as endow folate receptor targeting (H 39 GFP@MnO 2 NDs). The MnO 2 coating served to protect the internal protein cargo from premature release.…”

Nanotechnologies for enhancing cancer immunotherapy

“…Coupled with the cationization-triggered adsorption-mediated transcytosis (AMT), charge reversal and actively infiltration throughout the tumor tissue were realized, thereby overcoming the limitations of nano-structure transfer (high interstitial fluid pressure, tightly packed tumor cells, dense extracellular matrix) [63]. Folic acid (FA) [64,65], hyaluronic acid (HA) [33], specific ligands [66] are also often used as target tags. A recent focus on cell membrane and exosome permeability targeting needs to be mentioned [40,67,68].…”

“…As a result, UiO-Ra-DOX-CuS was proved to be more efficient for tumor-killing effect than monotherapy. Moreover, there are chemodynamic therapy (CDT) [78,79], sonodynamic therapy (SDT) [39,80], magnetic resonance imaging (MRI) [65,81] and photoacoustic imaging (PAI) [82] induced by physiochemical properties of material itself. They are frequently used in combination with conventional methods for cancer diagnosis, imaging and treatment because of noninvasive processes, enhanced spatiotemporal control, less time-consuming and more precise effect, termed "nanotheranostic" [83][84][85][86].…”