From Biomimicry to Translational Readiness: Barrier-Centric Design Principles for Intracellular Protein and Genome-Editing RNP Nanodelivery

Intracellular protein therapeutics face a sequential delivery problem: the formulation must preserve cargo integrity during administration and systemic exposure, reach the relevant tissue, enter the target cell, avoid destructive trafficking, release active cargo into the cytosol, and, when required, support organelle or nuclear access. This cascade makes particle internalisation an incomplete measure of delivery performance. This critical review reorganizes biomimetic nanocarriers around the biological barriers that determine functional intracellular bioavailability rather than around carrier origin alone. Virus-like particles (VLPs), engineered bacterial systems and outer-membrane vesicles (OMVs), biomineralized nanoparticles, exosomes/extracellular vesicles (EVs), and cell-membrane-coated nanocarriers are analysed as modular biological solutions to receptor recognition, immune clearance, membrane traversal, endosomal escape, triggered release, and tissue homing. Cargo requirements are stratified for enzymes and functional proteins, cytotoxic/regulatory proteins, Cas9 ribonucleoproteins (RNPs), base-editing complexes, and prime-editing systems. Mechanistic strengths are considered together with platform-specific failure modes, manufacturing constraints, quality attributes, safety liabilities, and evidence maturity. A Biomimetic Translation Readiness Framework (BTRF) is proposed across four domains-biological performance, manufacturing robustness, safety, and translational evidence-without assigning arbitrary numerical scores. The central thesis is that progress depends on matching the cargo to its dominant biological barrier, verifying intracellular delivery with functional endpoints, and developing reproducible manufacturing and safety performance in parallel with efficacy.