Photo-crosslinked poly(ethylene glycol)-b-poly(ϵ-caprolactone) nanoparticles for controllable paclitaxel release

Synthesis, Self-Assembly, and Drug Delivery Characteristics of Poly(methyl caprolactone-co-caprolactone)-b-poly(ethylene oxide) Copolymers with Variable Compositions of Hydrophobic Blocks: Combining Chemistry and Microfluidic Processing for Polymeric Nanomedicines

The synthesis, characterization, and self-assembly of a series of biocompatible poly(methyl caprolactone-co-caprolactone)-b-poly(ethylene oxide) amphiphilic block copolymers with variable MCL contents in the hydrophobic block are described. Self-assembly gives rise to polymeric nanoparticles (PNPs) with hydrophobic cores that decrease in crystallinity as the MCL content increases, and their morphologies and sizes show nonmonotonic trends with MCL content. PNPs loaded with the anticancer drug paclitaxel (PAX) give rise to in vitro PAX release rates and MCF-7 GI₅₀ (50% growth inhibition concentration) values that decrease as the MCL content increases. We also show for selected copolymers that microfluidic manufacturing at a variable flow rate enables further control of PAX release rates and enhances MCF-7 antiproliferation potency. These results indicate that more effective and specific drug delivery PNPs are possible through tangential efforts combining polymer synthesis and microfluidic manufacturing.

Controlling Structure and Function of Polymeric Drug Delivery Nanoparticles Using Microfluidics

We demonstrate control of multiscale structure and drug delivery function for paclitaxel (PAX)-loaded polycaprolactone-block-poly(ethylene oxide) (PCL-b-PEO) polymeric nanoparticles (PNPs) via synthesis and flow-directed shear processing in a two-phase gas-liquid microfluidic reactor. This strategy takes a page from the engineering of commodity plastics, where processing rather than polymer chemistry provides an experimental handle on properties and function. PNPs formed from copolymers with three different PCL block lengths show sizes, morphologies, and loading efficiencies that depend on both the PCL block length and the microfluidic flow rate. By varying flow rate and comparing with a conventional bulk method of PNP preparation, we show that flow-variable shear processing provides control of PNP sizes and morphologies and enables slower PAX release times (up to 2 weeks) compared to bulk-prepared PNPs. Antiproliferative effects against cultured MCF-7 breast cancer cells were greatest for PNPs formed at an intermediate flow rate, corresponding to small and low-polydispersity spheres formed uniquely at this flow condition. Formation and flow-directed nanoscale shear processing in gas-liquid microfluidic reactors provides a manufacturing platform for drug delivery PNPs that could enable more effective and selective nanomedicines through multiscale structural control.

Amphiphilic polyelectrolyte/prodrug nanoparticles constructed by synergetic electrostatic and hydrophobic interactions with cooperative pH-sensitivity for controlled doxorubicin delivery

To achieve higher therapeutic efficiency with catabatic side effects, desirable nanocarriers should be designed to retain the loaded drug tightly during the systemic circulation, but release the drug rapidly and efficiently upon endocytosis by tumor cells. Herein, to achieve "off-on" controlled delivery of DOX, novel amphiphilic polyelectrolyte/prodrug nanoparticles (NPs) with cooperative pH-sensitivity were constructed via synergistic electrostatic and hydrophobic interactions between slightly positively charged methoxy polyethylene glycol-b-(poly(2-(diisopropylamino) ethyl methacrylate-co-aminopropyl methacrylamide) (PEDPA) copolymer and negatively charged cis-aconityl-doxorubicin (CAD) prodrug (termed as PEDPA/CAD NPs). With polymer-prodrug synergistic noncovalent interactions, the drug loading content of PEDPA/CAD NPs could be improved up to 12.6% with favorable serum stability, and significantly lowered the drug leakage to 2.5% within 24 h at pH 7.4. However, nearly 80% of encapsulated drug could be released at pH 5.0 within 12 h, due to the cooperative effects of the protonation of PDPA blocks resulting in quick disassembly of NPs and the rapid hydrolysis of cis-aconityl linkage leading to charge-reverse of CAD. Moreover, the results of fluorescent microscopy imaging and flow cytometry measurements exhibited that DOX could be recovered and released rapidly from PEDPA/CAD NPs upon endocytosis and then exert therapeutic action in the cell nucleus. Importantly, the PEDPA/CAD NPs exhibited significantly higher antitumor efficiency in vivo with reduced nonspecific toxicity to normal tissues in comparation with free DOX. In summary, the NPs designed in this work, constructed by synergistic electrostatic and hydrophobic interactions with cooperative pH-sensitivity, which potentially resolved the dilemma between systemic stability and rapid intracellular drug release, would provide a promising nanomedicine platform for cancer therapy.