Dual stimuli polysaccharide nanovesicles for conjugated and physically loaded doxorubicin delivery in breast cancer cells

Polymeric prodrugs conjugated with reduction-sensitive dextran–camptothecin and pH-responsive dextran–doxorubicin: an effective combinatorial drug delivery platform for cancer therapy

Two types of stimuli-sensitive polymeric prodrugs for combinatorial cancer therapy have been prepared and found to exhibit favorable anticancer activity in vitro and in vivo.

Stimuli-responsive polymersomes for cancer therapy

This review focuses on stimuli-responsive polymersomes for cancer therapy, which can be disintegrated by recognizing the specific environments of cancer (e.g., low pH, bioreductive environment, over-expressed enzymes,etc.).

Biodegradable multi-blocked polyurethane micelles for intracellular drug delivery: the effect of disulfide location on the drug release profile

Polyurethane micelles with disulfide bonds positioned mainly either at the hydrophobic PCL junctions (PU-SS-C) or at the connections between the hydrophilic PEG and hydrophobic PCL blocks (PU-SS-I) were developed as a antitumor drug carriers.

Biodegradable pH-sensitive polyurethane micelles with different polyethylene glycol (PEG) locations for anti-cancer drug carrier applications

Biodegradable pH sensitive polyurethane micelles with a dense brush like coating of PEG were prepared. The PTX-loaded PEG-g-PU-3 micelles exhibited potent cytotoxicity against H460 cancer cells compared to PEG-b-PU-3 and PEG-c-PU-3 micelles.

Long-term and oxidative-responsive alginate–deferoxamine conjugates with a low toxicity for iron overload

Long-term and oxidative-responsive alginate–deferoxamine conjugates.

Enzyme and Thermal Dual Responsive Amphiphilic Polymer Core-Shell Nanoparticle for Doxorubicin Delivery to Cancer Cells

Dual responsive polymer nanoscaffolds for administering anticancer drugs both at the tumor site and intracellular compartments are made for improving treatment in cancers. The present work reports the design and development of new thermo- and enzyme-responsive amphiphilic copolymer core-shell nanoparticles for doxorubicin delivery at extracellular and intracellular compartments, respectively. A hydrophobic acrylate monomer was tailor-made from 3-pentadecylphenol (PDP, a natural resource) and copolymerized with oligoethylene glycol acrylate (as a hydrophilic monomer) to make new classes of thermo and enzyme dual responsive polymeric amphiphiles. Both radical and reversible addition-fragmentation chain transfer (RAFT) methodologies were adapted for making the amphiphilic copolymers. These amphiphilic copolymers were self-assembled to produce spherical core-shell nanoparticles in water. Upon heating, the core-shell nanoparticles underwent segregation to produce larger sized aggregates above the lower critical solution temperature (LCST). The dual responsive polymer scaffold was found to be capable of loading water insoluble drug, such as doxorubicin (DOX), and fluorescent probe-like Nile Red. The drug release kinetics revealed that DOX was preserved in the core-shell assemblies at normal body temperature (below LCST, ≤ 37 °C). At closer to cancer tissue temperature (above LCST, ∼43 °C), the polymeric scaffold underwent burst release to deliver 90% of loaded drugs within 2 h. At the intracellular environment (pH 7.4, 37 °C) in the presence of esterase enzyme, the amphiphilic copolymer ruptured in a slow and controlled manner to release >95% of the drugs in 12 h. Thus, both burst release of cargo at the tumor microenvironment and control delivery at intracellular compartments were accomplished in a single polymer scaffold. Cytotoxicity assays of the nascent and DOX-loaded polymer were carried out in breast cancer (MCF-7) and cervical cancer (HeLa) cells. Among the two cell lines, the DOX-loaded polymers showed enhanced killing in breast cancer cells. Furthermore, the cellular uptake of the DOX was studied by confocal and fluorescence microscopes. The present investigation opens a new enzyme and thermal-responsive polymer scaffold approach for DOX delivery in cancer cells.

Core-shell polymer nanoparticles for prevention of GSH drug detoxification and cisplatin delivery to breast cancer cells

Platinum drug delivery against the detoxification of cytoplasmic thiols is urgently required for achieving efficacy in breast cancer treatment that is over expressed by glutathione (GSH, thiol-oligopeptide). GSH-resistant polymer-cisplatin core-shell nanoparticles were custom designed based on biodegradable carboxylic functional polycaprolactone (PCL)-block-poly(ethylene glycol) diblock copolymers. The core of the nanoparticle was fixed as 100 carboxylic units and the shell part was varied using various molecular weight poly(ethylene glycol) monomethyl ethers (MW of PEGs = 100-5000 g mol(-1)) as initiator in the ring-opening polymerization. The complexation of cisplatin aquo species with the diblocks produced core-shell nanoparticles of 75 nm core with precise size control the particles up to 190 nm. The core-shell nanoparticles were found to be stable in saline solution and PBS and they exhibited enhanced stability with increase in the PEG shell thickness at the periphery. The hydrophobic PCL layer on the periphery of the cisplatin core behaved as a protecting layer against the cytoplasmic thiol residues (GSH and cysteine) and exhibited <5% of drug detoxification. In vitro drug-release studies revealed that the core-shell nanoparticles were ruptured upon exposure to lysosomal enzymes like esterase at the intracellular compartments. Cytotoxicity studies were performed both in normal wild-type mouse embryonic fibroblast cells (Wt-MEFs), and breast cancer (MCF-7) and cervical cancer (HeLa) cell lines. Free cisplatin and polymer drug core-shell nanoparticles showed similar cytotoxicity effects in the HeLa cells. In MCF-7 cells, the free cisplatin drug exhibited 50% cell death whereas complete cell death (100%) was accomplished by the polymer-cisplatin core-shell nanoparticles. Confocal microscopic images confirmed that the core-shell nanoparticles were taken up by the MCF-7 and HeLa cells and they were accumulated both at the cytoplasm as well at peri-nuclear environments. The present investigation lays a new foundation for the polymer-based core-shell nanoparticles approach for overcoming detoxification in platinum drugs for the treatment of GSH over-expressed breast cancer cells.

Real-Time Drug Release Analysis of Enzyme and pH Responsive Polysaccharide Nanovesicles

The accurate estimation of drug release kinetics of polymeric vehicles is an indispensable prerequisite for the developments of successful drug carriers for cancer therapy. The present investigation reports the development of time-resolved fluorescence spectroscopic approach for the real-time release kinetics of fluorophore loaded polysaccharide vesicles that are potential vectors in cancer treatment. The polysaccharide vesicles were custom designed with appropriate enzyme and pH responsiveness and loaded with water-soluble biocompatible fluorophore Rhodamine B (Rh-B). The semipermeable membrane dialysis method along with steady state absorbance spectroscopic technique was found to be inaccurate for the estimation of drug release. Time correlated single photon counting (TCSPC) technique was found to exhibit significant difference in excited state decay profiles and fluorescent lifetime of Rh-B in the free and polymer bound states. This enabled the establishment of real-time drug release protocols by TCSPC method for polysaccharide vesicles that are responsible to pH and enzyme with respect to intracellular compartments. Real-time analysis predicted the release kinetics 20-25% higher accuracy when compared to the dialysis method under in vitro conditions. Moreover, the ability of enzyme to cleave the polysaccharide vesicles was further validated by docking studies. The positioning of the molecules in active site of enzyme and the binding energy data were generated using AUTODOCK program to study the rupture of polysaccharide vesicles. This new TCSPC technique could be very useful for studying the drug release pattern of synthetic polymer vesicles loaded with Rh-B fluorophore.