Table 3.
The comparison of lipid carriers for mRNA delivery.
| Carrier type | Characteristic | Advantage | Disadvantage |
|---|---|---|---|
| LPs | Spherical vesicles with a lipid bilayer. | Low toxicity, high biocompatibility, protection of envelope. | Low EE. |
| LPPs | Spherical vesicles with a cationic lipid bilayer. | Higher EE. | Significant toxicity. |
| LLPs | Sphere-shaped, multi/monolayer nanosized vesicle. | Less toxic, higher EE, improved endosome escape. | Instability under non-freezing conditions. |
| SLNs | Spherical vesicles with a core consisting of a solid matrix. | Higher physical stability, more robust mRNA protection, and higher delivery efficacy. | Expulsion of the incorporated mRNA. |
| NLCs | Spherical vesicles with a core consisting of both solid and liquid lipids. | Higher physicochemical stability, higher drug-loading capacity, less drug leakage, and controlled drug release. | In the preparation (high-pressure homogenization) process, the high temperature may promote the degradation of drug and the carriers. |
| LPNs | Core-shell nanoparticle structure composed of polymer core and lipid shell. | Less biofouling, prolonged half-life, sustained drug release. | Polymeric materials may bring unwanted side effects. |
| Nanoemulsions | A heterogeneous colloidal dispersion of nanodroplets dispersed in another liquid phase. | Prolonged half-life, less irritation. | Emulsifier incorporation may generate safety risks. |
| Exosomes | Nanosized lipid vesicles secreted from living cells, ranging from 30 to 150 nm. | Extremely high biocompatibility and stability, biological barrier permeability, and extended circulation time. | Modification is required to obtain high target site affinity. The preparation of exosomes is time-consuming with high costs. |
| LPTs | Heterogeneous NPs present in biological fluids, mainly composed of lipids and proteins. | Extremely high biocompatibility, non-immunogenicity and stability, intrinsic targeting ability. | The purification of LPTs is time-consuming and poorly scalable. |
These lipid carriers have lower toxicity and higher inclusion protection than non-lipid vectors. The advantages and disadvantages of the carriers were demonstrated by comparing with LPs.
EE, encapsulation efficiency; LPs, liposomes; LPNs, lipid-polymer hybrid nanoparticles; LLPs, liposome-like nanoparticles; LPPs, lipoplexes; LPTs, lipidprotein-particles; NLCs, nanostructured lipid carriers; SLNs, solid lipid nanoparticles.