. Author manuscript; available in PMC: 2013 Apr 7.

Published in final edited form as: Chem Soc Rev. 2012 Feb 14;41(7):2545–2561. doi: 10.1039/c2cs15327k

Table 1.

Summary of the important features of polymeric nanoparticles designed for biomedical delivery applications.

Feature	Description
Stealth	○ A dense brush of neutral hydrophilic flexible polymer to prevent adsorption of plasma proteins and avoid recognition by the MPS and prolong the blood circulation time, and thereby allowing the accumulation of the nanoparticles at sites with impaired vasculature via the EPR effect ○ PEG is the most commonly utilized polymer
Surface chemistry	○ The surface chemistry of the nanomaterials greatly impact their toxicity, immunogenicity and biodistribution ○ Excess positive charge results in rapid opsonization and clearance with possible blood vessels and capillary occlusion
Smart ingredients	○ Cell-recognition moieties enhance the selective cellular uptake ○ Targeting subcellular compartments (e.g. nuclear localization sequence for nuclear delivery) ○ Skin, mucus (mucolytic) or cell-penetration enhancers ○ Endosomolytic polymers or lipids to increase the intracellular delivery and avoid lysosomal degradation ○ Stimuli-responsiveness (temperature, pH, oxidation, reduction, light, magnetic field, ultrasound, etc.) allows the controlled-drug release at specific sites or under applied conditions ○ “Multivalency”, “bio-mimicking” or “ self-communication” are recently-applied approaches to enhance the delivery efficiency ○ Any added component to the composition of the nanoparticle may impact their biodistribution, clearance and immunogenicity
Size	○ Intermediate size (20–200 nm) have the highest potential for in vivo applications
Shape/aspect ratio	○ Various morphologies and/or aspect ratios can have different solubilization capacities, blood circulation time, biodistribution, toxicity, cellular uptake and intracellular fate
Route of administration	○ The route of administration influences the stability and delivery efficiency of the nanoparticles ○ There are different barriers at the various entry routes of the body (e.g. pH, enzymes, etc.) ○ Auxiliary devices can enhance the delivery efficiency by localizing the nanoparticles at the target sites
Stability	○ Drug leakage, dissociation of nanoparticles and detachment of the surface-decorating moieties are detrimental to the efficacy of the nanoparticles ○ Stereocomplexation, non-covalent interactions and crosslinking are efficient techniques to enhance the kinetic stability of nanoparticles