Intracellular Protein Delivery Systems

Intracellular protein delivery systems aim to transport functional proteins across the plasma membrane and release them into the cytosol or organelles, thereby expanding the range of therapeutic targets to intracellular pathways. These systems address key challenges including the large size and poor membrane permeability of proteins, susceptibility to proteolytic degradation and off-target immunogenicity. Strategies span chemical modification of proteins, incorporation into nanocarriers (lipid-based, polymeric or inorganic), use of cell-penetrating peptides and stimuli-responsive assemblies that trigger cargo release in response to pH, redox potential or specific enzymes. Progress in materials design has improved endosomal escape and biodistribution, while advances in targeting moieties and biomimetic formulations have enhanced cellular uptake and tissue selectivity. Applications range from enzyme replacement and pro-apoptotic therapies in oncology to intracellular gene editing using ribonucleoprotein complexes. Interdisciplinary efforts in nanotechnology, chemical biology and polymer science continue to refine these platforms for precise, efficacious delivery of protein therapeutics.

Research from Nature Portfolio

Fluoroamphiphile co-assembly has been shown to form stable nanoparticles that encapsulate diverse proteins without denaturation, facilitating efficient cellular uptake and cytosolic release. Introduction of fluorocarbon chains enhances nanoparticle uniformity and endosomal disruption, while minimising toxicity. Structure-activity studies reveal an optimal fluorination degree for protein encapsulation and delivery, highlighting fluoroamphiphiles as a versatile platform for intracellular protein transport.

pH-responsive, charge-reversible lipid nanoparticles incorporating a diethylenediamine-modified phosphoglyceride have been developed to encapsulate negatively charged proteins with high efficiency. Upon endocytosis, protonation of lipid head groups triggers charge inversion and promotes endosomal escape, resulting in cytosolic distribution in the majority of target cells. This approach demonstrates precise control over protein encapsulation and intracellular release using a single lipid component.

Intracellular Protein Delivery Systems publication trend

The graph below shows the total number of articles in intracellular protein delivery systems across all publications each year (not limited to Nature Index journals).

Technical terms

Nanocarrier: A nanoscale delivery vehicle designed to encapsulate and transport therapeutic molecules into cells.

Endocytosis: Cellular uptake process in which extracellular material is engulfed within membrane-bound vesicles.

Endosomal escape: Mechanism by which internalised cargo breaches endosomal membranes to reach the cytosol.

Stimuli-responsive: Property of a system to alter structure or release its cargo in response to environmental triggers such as pH or redox changes.

Fluoroamphiphile: An amphiphilic molecule bearing fluorocarbon segments that facilitate nanoparticle self-assembly and membrane interactions.

Poly(β amino ester): A biodegradable cationic polymer used to complex with and deliver proteins into the cytosol.

Cytosolic delivery: Direct transport of therapeutic cargo into the cell’s cytosol, bypassing lysosomal degradation.

References

1. Targeted protein delivery based on stimuli‐triggered nanomedicine. Exploration (2023).
2. The fluorination effect of fluoroamphiphiles in cytosolic protein delivery. Nature Communications (2018).
3. Nanotechnological Strategies for Protein Delivery. Molecules (2018).
4. Cytosolic protein delivery using pH-responsive, charge-reversible lipid nanoparticles. Scientific Reports (2021).
5. Guanidyl-Rich Poly(β Amino Ester)s for Universal Functional Cytosolic Protein Delivery and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) Cas9 Ribonucleoprotein Based Gene Editing. ACS Nano (2023).