Table 2.
Methods used to bioengineer the most commonly used PNPs for a range of bioapplications.
| PNP | In Vitro Loading Mechanism | Cov Biocon 1 | Point Mut 2 | UAA 3 | Pep Disp 4 | Prot Disp 5 | Modul Assem 6 | Encapsulated Cargo | Applications | Ref. | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Diffusion 7 | In Vitro | In Vivo | |||||||||||
| VLPs | CCMV | pH; Ionic strength | • | • | • | • | Metals; small-molecule drugs; nucleic acids; organic polymers | Drug delivery; vaccines; bioimaging; prodrug activation; biocatalysis | [30,117,118,119,120,121,122,123,124] | ||||
| CPMV | • | • | • | • | Metals; fluorescent probes; biotin; organic polymers | Drug delivery; vaccines; bioimaging | [31,91,125,126,127,128,129] | ||||||
| HBc | Denaturants | • | • | • | • | • | • | Metals; small-molecule drugs; fluorescent probes; nucleic acids | Drug delivery; vaccines; bioimaging | [37,130,131,132,133,134,135] | |||
| MS2 | pH; Denaturants | • | • | • | • | • | Fluorescent probes; photosensitizers | Metals; small-molecule drugs; nucleic acids | Proteins | Drug delivery; vaccines; bioimaging; biocatalysis | [114,136,137,138,139,140] | ||
| P22 | pH | • | • | • | • | Metals; fluorescent probes; biotin; organometallic polymers | Proteins | Proteins; peptides; epitopes; nucleic acids | Drug delivery; vaccines; nanomaterial synthesis; biocatalysis; solubility enhancement | [107,141,142,143,144,145,146] | |||
| Qβ | pH; Denaturants | • | • | • | • | • | Fluorescent probes; cationic polymers | Metals; small-molecule drugs; fluorescent probes; nucleic acids | Proteins | Drug delivery; vaccines; bioimaging; nanomaterial synthesis | [24,97,132,137,147,148] | ||
| Dps | • | • | • | Metals | Drug delivery; nanomaterial synthesis | [104,149,150] | |||||||
| E2 | Denaturants | • | • | • | • | • | Small-molecule drugs; fluorescent probes | Nucleic acids | Drug delivery; vaccines; biocatalysis; antibody purification | [48,82,151,152,153,154,155,156] | |||
| Encapsulin | pH; Denaturants | • | • | • | • | Metals | Proteins | Proteins | Drug delivery; bioimaging; immunotherapy; antimicrobials; biocatalysis | [9,50,51,52,157,158,159] | |||
| Ferritin | pH | • | • | • | • | • | Metals; small-molecule drugs | Bioactive compounds; metals; small-molecule drugs | Metals | Solubility enhancement; drug delivery; vaccines; bioimaging; immunotherapy; nanomaterial synthesis | [27,102,160,161,162,163,164,165,166,167,168,169] | ||
| Hsp | Temperature | • | • | • | • | Metals | Metals; small-molecule drugs; dyes; fluorescent probes | Drug delivery; nanomaterial synthesis; biocatalysis | [59,87,170,171,172] | ||||
| LS | Ionic strength | • | • | • | • | • | Proteins | Drug delivery; vaccines; bioimaging; biocatalysis | [62,98,173,174,175,176,177] | ||||
| Vault | “Breathing mechanism” | • | • | Metals; proteins; epitopes; antigens | Proteins | Solubility enhancement; drug delivery; vaccines; bioimaging; immunotherapy; bioremediation | [178,179,180,181,182,183,184,185,186,187] | ||||||
1 Covalent bioconjugation; 2 Point Mutation; 3 Unnatural amino acid incorporation; 4 Peptide display; 5 Whole protein display; 6 Modular assembly; 7 Pore-mediated diffusion.