Stimuli-responsive nanoparticles for biomedical applications
Stimuli-responsive NPs with excellent stability, high loading efficiency, encapsulation of multiple agents, targeting to certain cells, tissues or organs of the body, can be used as delivery tools. These NPs contain a hydrophobic inner core and hydrophilic outer shell, which endows them with high stability and the ability to load therapeutic agents with high encapsulation efficiency. The NPs are preferably formed from amphiphilic stimulus-responsive polymers or a mixture of amphiphilic and hydrophobic polymers or compounds, at least one type of which is stimuli-responsive. These NPs can be made so that their cargo is released primarily within target certain cells, tissues or organs of the body, upon exposure to endogenous or exogenous stimuli. The rate of release can be controlled so that it may be a burst, sustained, delayed, or a combination thereof. The NPs have utility as research tools or for clinical applications including diagnostics, therapeutics, or combination of both.
1 . A stimulus responsive polymer comprising:
(a) a hydrophilic portion; and
(b) a hydrophobic portion modified with a charged group,
wherein the hydrophilic portion and the hydrophobic portion are connected by a covalent linker; and
wherein the stimulus responsive polymer comprises Formula I: (X) m —(Y) n ,
wherein m and n are independently integers between one and 1000, X is a hydrophobic polymer in the hydrophobic portion and comprises a glycidyl methacrylate and Y is a hydrophilic polymer in the hydrophilic portion and comprises polyethylene glycol, and
wherein the polymer comprises methoxyl-polyethylene glycol-b-poly (2-(diisopropylamino) ethylmethacrylate-co-glycidyl methacrylate-tetraethylenepentamine-C14) (Meo-PEG-b-P (DPA-CO-GMA-TEPA-C14)).
2 . The stimulus responsive polymer of claim 1 , wherein the charged group comprises a positive charge.
3 . The stimulus responsive polymer of claim 1 , wherein the stimulus comprises a pH buffer.
4 . The stimulus responsive polymer of claim 3 , wherein the buffer comprises a pH of about 4 to about 7.5.
5 . The stimulus responsive polymer of claim 4 , wherein the buffer comprises a pH of about 5 to about 7.
6 . The stimulus responsive polymer of claim 1 , wherein the hydrophobic portion further binds a nucleic acid.
7 . The stimulus responsive polymer of claim 1 , wherein the stimulus responsive polymer has a pKa between 6.0 and 6.5.
8 . The stimulus responsive polymer of claim 1 , wherein the stimulus responsive polymer is complexed with a nucleic acid.
9 . The stimulus responsive polymer of claim 8 , wherein the nucleic acid is an antisense oligonucleotide, an siRNA, a shRNA, an miRNA, a piRNA, an external guide sequence (EGS), a ribozyme, or an aptamer.