Biodegradable Amphiphilic Block Copolymers Research Articles

Theranostics Using Indocyanine Green Lactosomes.

Simple SummaryLactosomes™ are biocompatible nanoparticles that can be used for cancer tissue imaging and drug delivery. Lactosomes are amphiphilic micelles in which the particle size can be controlled in the range of 20 to 100 nm. Lactosomes can also be loaded with imaging probes and anticancer agents. Indocyanine green-loaded lactosomes accumulate in cancer tissues and function as a photosensitizer, which simultaneously enables diagnosis and photodynamic therapy. This approach can facilitate the treatment of cancers in unresectable tissues, which can lead to improved quality of life for patients. This review provides an overview of lactosomes with respect to molecular design, accumulation in cancer tissues, and theranostics applications. We also address some outstanding questions and future directions in cancer theranostics.Lactosomes™ are biocompatible nanoparticles that can be used for cancer tissue imaging and drug delivery. Lactosomes are polymeric micelles formed by the self-assembly of biodegradable amphiphilic block copolymers composed of hydrophilic polysarcosine and hydrophobic poly-L-lactic acid chains. The particle size can be controlled in the range of 20 to 100 nm. Lactosomes can also be loaded with hydrophobic imaging probes and photosensitizers, such as indocyanine green. Indocyanine green-loaded lactosomes are stable for long-term circulation in the blood, allowing for accumulation in cancer tissues. Such lactosomes function as a photosensitizer, which simultaneously enables fluorescence diagnosis and photodynamic therapy. This review provides an overview of lactosomes with respect to molecular design, accumulation in cancer tissue, and theranostics applications. The use of lactosomes can facilitate the treatment of cancers in unresectable tissues, such as glioblastoma and head and neck cancers, which can lead to improved quality of life for patients with recurrent and unresectable cancers. We conclude by describing some outstanding questions and future directions for cancer theranostics with respect to clinical applications.

Intelligent Paper-Free Sprayable Skin Mask Based on an In Situ Formed Janus Hydrogel of an Environmentally Friendly Polymer.

Traditional skin care masks usually use a piece of paper to hold the aqueous essences, which are not environmentally friendly and not easy to use. While a paper-free mask is desired, it is faced with a dilemma of moisture holding and rapid release of encapsulated bioactive substances. Herein, a paper-free sprayable skin mask is designed from an intelligent material-a thermogel which undergoes sol-gel-suspension transitions upon heating-to solve this dilemma. A synthesized block copolymer of poly(ethylene glycol) and poly(lactide-co-glycolide) with appropriate ratios can be dissolved in water, and thus easily mixed with a biological substance. The mixture is sprayable. After spraying, a Janus film is formed in situ with a physical gel on the outside and a suspension on the inside facing skin. Thus, both moisture holding and rapid release are achieved. Such a thermogel composed of biodegradable amphiphilic block copolymers loaded with nicotinamide as a skin mask is verified to reduce pigmentation on a 3D pigmented reconstructed epidermis model and further in a clinical study. This work might be stimulating for investigations and applications of biodegradable and intelligent soft matter in the fields of drug delivery and regenerative medicine.

Therapeutic Stomatocytes with Aggregation Induced Emission for Intracellular Delivery.

Bowl-shaped biodegradable polymersomes, or stomatocytes, have much potential as drug delivery systems, due to their intriguing properties, such as controllable size, programmable morphology, and versatile cargo encapsulation capability. In this contribution, we developed well-defined therapeutically active stomatocytes with aggregation-induced emission (AIE) features by self-assembly of biodegradable amphiphilic block copolymers, comprising poly(ethylene glycol) (PEG) and AIEgenic poly(trimethylene carbonate) (PTMC) moieties. The presence of the AIEgens endowed the as-prepared stomatocytes with intrinsic fluorescence, which was employed for imaging of cellular uptake of the particles. It simultaneously enabled the photo-mediated generation of reactive oxygen species (ROS) for photodynamic therapy. The potential of the therapeutic stomatocytes as cargo carriers was demonstrated by loading enzymes (catalase and glucose oxidase) in the nanocavity, followed by a cross-linking reaction to achieve stable encapsulation. This provided the particles with a robust motile function, which further strengthened their therapeutic effect. With these unique features, enzyme-loaded AIEgenic stomatocytes are an attractive platform to be exploited in the field of nanomedicine.

Minocycline hydrochloride loaded mPEG-PCLA membranes: Preparation and in vitro evaluation for periodontitis therapy

This study was aimed at alleviating shortcomings in the treatment of periodontitis by preparation of a biopolymer membrane loaded with minocycline hydrochloride (MH) inserted into periodontal pockets to treat infections. Monomethoxy-poly (ethylene glycol)-poly (ε-caprolactone-co-L-lactide) (mPEG-PCLA) is a biocompatible and biodegradable amphiphilic block copolymer. It, therefore, has attracted considerable attention in drug delivery systems and periodontal treatment. We chose it as a membrane material for MH-drug loading. The MH-loaded membranes were prepared by the solvent casting technique with the content of 5, 8 and 10 wt.%, respectively. Fourier transform infrared spectra (FTIR) revealed no interaction between MH and polymer. The drug-loaded membrane surface morphology was investigated by scanning electron microscopy (SEM). In vitro release studies showed that the initial drug release exceeded 40% within 24 h, followed by a sustained release for up to 2 weeks, which would enable the therapeutic level to maintain over a longer time. The antibacterial activity studies in vitro demonstrated a positive effect on the periodontal pathogen. MH drug-loaded membranes have no adverse effect on the growth of periodontal ligament fibroblasts in the MTT test. The study suggests that mPEG-PCLA membranes containing MH are a potential antibacterial drug delivery system for local treatment of periodontitis.

Synthesis and characterization of castor oil-derived oxidation-responsive amphiphilic block copolymers: Poly(ethylene glycol)-b-poly(11-((2-hydroxyethyl)thio)undecanoate)

The synthesis of oxidation-responsive biodegradable amphiphilic block copolymers by Candida Antarctica Lipase B (CALB)-catalyzed self-polycondensation of 11-((2-hydroxyethyl)-thio)undecanoic acid (TEHA) initiated by methoxy polyethyleneglycol (mPEG-OH) of different molecular weights has been described. SEC and mono and bidimensional NMR have been used to confirm the molecular weight and structure of the polymers and copolymers. DSC and TGA have been employed to characterize their thermal properties. The oxidation behaviour in front of H2O2 as well as the structure of the oxidized products has been established using NMR, FTIR and Raman spectroscopies. The different block copolymers could self-assemble to form nanosized micelles in aqueous solution with low critical micelle concentration (CMC), showing potential application as dual responsive systems in drug delivery. Micellar characteristics were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). These micelles are prone to undergo a H2O2-triggered disassembly due to the oxidizable thioether groups in the hydrophobic core. Nile Red was used as model for hydrophobic drugs to test the oxidative triggered release of a copolymer, which showed progressive release in few hours upon the addition of H2O2.

Amphiphilic poly(caprolactone-b-N-hydroxyethyl acrylamide) micelles for controlled drug delivery.

To increase the bioavailability and water solubility of hydrophobic medicine, an amphiphilic block copolymer, polycaprolactone-block-polyhydroxyethyl acrylamide (PCL-b-PHEAA), was synthesized. The copolymer can self-assemble into micelles by dialysis. The micelles were characterized by the Tyndall effect, static drop method, fluorescence spectrometry, dynamic light scattering, scanning electron microscopy and transmission electron microscopy. Ibuprofen was encapsulated inside the micelles by dialysis as a model medicine. The results show that the amphiphilic copolymer forms a uniform micelle system, with spherical micelles dispersed well in solution which have a low critical micelle concentration. In addition, the system shows good amphipathic behavior. Average particle size of a micelle is 104 nm, which increases a lot after drug loading and standing for half a month. In the first few hours, the cumulative release of the drug increases gradually; the rate of increase in the first ten hours is faster, then reaching a plateau which tends to be flat finally. It is similar under two different pH conditions. This biocompatible, biodegradable amphiphilic block copolymer has potential applications in the biomedical field.

Abstract 4662: Comparing 2D and 3D culture models for in vitro therapeutic screening of paclitaxel loaded micelles co-administered with iRGD peptide

Abstract Clinical efficacy of paclitaxel, a potent chemotherapeutic agent, is limited by its nonspecificity that leads to toxic side effects. Polymeric micellar formulations of paclitaxel were designed with the long term goals of decreasing toxicity by tumor targeting, increasing circulation time, and enhancing permeability and retention in solid tumors. Biodegradable amphiphilic block copolymers that self assemble into micelles were used to entrap hydrophobic paclitaxel in the core. Traditional 2D cell culture models are standard for cytotoxicity assays. However, they lack the diffusion gradient and cell to cell interactions present in solid tumors which 3D multicellular tumor spheroids are capable of providing. We evaluated the in vitro cytotoxicity of polymeric micelles entrapping paclitaxel in 3D multicellular tumor spheroids of triple negative breast cancer cells and compared it with the standard 2D model. We added the cell penetrating iRGD peptide with the expectation that the iRGD peptide will increase the cellular uptake of the paclitaxel micelles. Particle uptake is enhanced due to the interaction of the iRGD peptide with the highly expressed integrin receptor on the cell surface, followed by neuropilin receptor binding which mediates an active transport system for deep tumor permeation. Paclitaxel loaded micelles were prepared and the drug content was analyzed. The cytotoxicity of the micellar paclitaxel nanocarrier system was studied in both the 2D and 3D cell culture models. Micellar paclitaxel induced cytotoxicity was significantly higher than free paclitaxel for the same concentrations of paclitaxel. Furthermore, a synergistic growth inhibitory response was observed upon coadministration of iRGD compared to treatment with the paclitaxel loaded nanocarriers on their own. Significantly higher concentration of the drug was needed in the 3D cultures to achieve comparable levels of cytotoxicity to the 2D cell culture models. This suggested that multicellular tumor spheroids exhibit higher resistance to anticancer drugs, supporting the fact that 3D culture is the better model to study in vitro cytotoxicity and likely to produce biorelevant data. Citation Format: Nayela N. Chowdhury, Nandita G. Das, Sudip K. Das. Comparing 2D and 3D culture models for in vitro therapeutic screening of paclitaxel loaded micelles co-administered with iRGD peptide [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4662.

Thermoresponsive and Biodegradable Amphiphilic Block Copolymers with Pendant Functional Groups.

To develop the biodegradability and thermoresponsive hydrogel, in this work we designed a pendant-functionalized, thermoresponsive, amphiphilic block copolymer. Methoxy poly(ethylene glycol) (MPEG)-b-[poly(ε-caprolactone)-ran-poly(ε-caprolactone-3-one)-ran-polylactic acid] (MCL) and (MPEG-b-[PCL-ran-POD-ran-PLA]) [MCL-(CO)] block copolymers were prepared by ring-opening polymerization of ε-caprolactone, OD and lactide monomers. The subsequent derivatization of MCL-(CO) provided MPEG-b-[PCL-ran-poly(ε-caprolactone-3-COOH)-ran-PLA] [MCL-(COOH)] with COOH pendant groups and MPEG-b-[PCL-ran-poly(ε-caprolactone-3-NH2)-ran-PLA] [MCL-(NH2)] with NH2 pendant groups. The measured segment ratios of MCL-(CO), MCL-(COOH), and MCL-(NH2) agreed well with the target ratios. The abundances of the COOH and NH2 groups in the MCL-(COOH) and MCL-(NH2) copolymers were determined by 1H- and 13C-nuclear magnetic resonance spectroscopy, and agreed well with the target abundances. MCL-(CO), MCL-(COOH), and MCL-(NH2) formed homogeneous, white, opaque emulsions at room temperature. Rheological analysis of the block copolymer suspensions indicated a solution-to-hydrogel phase transition as a function of temperature. The solution-to-hydrogel phase transitions and the biodegradation of MCL-(CO), MCL-(COOH), and MCL-(NH2) were affected by varying the type (ketone, COOH, or NH2) and abundance of the pendant groups. MCL-(CO), MCL-(COOH), and MCL-(NH2) with ketone, COOH, and NH2 pendant groups showed solution-to-hydrogel phase transitions and biodegradation behaviors that depended on both the type and number of pendant groups.

Matrix Metalloproteinase-Responsive Multifunctional Peptide-Linked Amphiphilic Block Copolymers for Intelligent Systemic Anticancer Drug Delivery.

The amphiphilic block copolymer anticancer drug nanocarriers clinically used or in the progress of clinical trials frequently suffer from modest final therapeutic efficacy due to a lack of intelligent features. For example, the biodegradable amphiphilic block copolymer, poly(ethylene glycol)-b-poly(d,l-lactide) (PEG-PDLLA) has been approved for clinical applications as a paclitaxel (PTX) nanocarrier (Genexol-PM) due to the optimized pharmacokinetics and biodistribution; however, a lack of intelligent features limits the intracellular delivery in tumor tissue. To endow the mediocre polymer with smart properties via a safe and facile method, we introduced a matrix metalloproteinase (MMP)-responsive peptide GPLGVRGDG into the block copolymer via efficient click chemistry and ring-opening polymerization to prepare PEG-GPLGVRGDG-PDLLA (P1). P1 was further self-assembled into micellar nanoparticles (NPs) to load PTX, which show MMP-2-triggered dePEGylation due to cleavage of the peptide linkage. Moreover, the residual VRGDG sequences are retained on the surface of the NPs after dePEGylation, which can serve as ligands to facilitate the cellular uptake. The cytotoxicity of PTX loaded in P1 NPs against 4T1 cells is significantly enhanced as compared with free PTX or PTX-loaded PEG-GPLGVRG-PDLLA (P2) and PEG-PDLLA (P3) NPs. In vivo studies confirmed that PTX-loaded P1 NPs show prolonged blood circulation, which are similar to P2 and P3 NPs but exhibit more-efficient accumulation in the tumor site. Ultimately, PTX-loaded P1 NPs display statistically significant improvement of antitumor activity against tumor-bearing mice via systemic administration. Therefore, the strategy by facile incorporation of a responsive peptide linkage between PEG and PDLLA is a promising approach to improving the therapeutic efficacy of anticancer-drug-loaded amphiphilic block copolymer micelles.

Redox-responsive molecular gels based on camptothecin prodrug with disulfide linkage for controlled and sustained drug release

A novel camptothecin (CPT) prodrug was successfully synthesized by conjugating CPT to adamantanecarboxylic acid (AD) via a cleavable disulfide linkage. The resulting CPT-ss-AD prodrug could act as a low molecular weight gelator to form molecular gels in water/water-miscible organic solvent mixture. Meanwhile, biodegradable amphiphilic block copolymer mPEG-b-P (MAC-co-DTC) (PPMD) was also employed as an organic framework together with CPT-ss-AD to form gel structure. CPT-ss-AD/PPMD gel exhibited less compact molecular arrangement but much more stability than CPT-ss-AD gel. The two kinds of gels could effectively release the original CPT under reductive condition at a near-constant rate without any initial burst. As compared to CPT-ss-AD single-component gel, the two-component gel, CPT-ss-AD/PPMD, had a significantly higher release rate of CPT, while 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assays also indicated highly potent cytotoxic activity against HeLa cells.

Thermoresponsive star-like γ-substituted poly(caprolactone)s for micellar drug delivery

Fully biodegradable amphiphilic thermoresponsive star block copolymers featuring 4 and 6 arms are reported for micellar delivery of doxorubicin.

Polymer Topology Driven Enzymatic Biodegradation in Polycaprolactone Block and Random Copolymer Architectures for Drug Delivery to Cancer Cells

The present investigation reports polymer topology design principle for programming the enzymatic biodegradation and delivery of anticancer drugs at the intracellular compartments of breast and cervical cancers. To accomplish this goal, new classes of biodegradable amphiphilic block and random copolymers based on hydrophilic carboxylic-functionalized polycaprolactone (CPCL) and hydrophobic polycaprolactone (PCL) units were designed via ring-opening polymerization methodology. The interchain interactions and their packing were directly controlled by the topology of the polymers, and the block copolymers were found to be as semicrystalline materials. These amphiphilic block and random polymers were readily dispersible in water, and they self-assembled into <200 nm nanoparticles. These nanoparticles exhibited excellent capability for loading anticancer drug doxorubicin (DOX) in the hydrophobic pocket. In vitro drug release kinetics revealed that the polymer nanoscaffolds were stable under physiological condi...

PH‐responsive core crosslinked polycarbonate micelles via thiol‐acrylate Michael addition reaction

ABSTRACTA facile method for the construction of pH‐responsive core crosslinked micelles (CCLMs) based on polycarbonate was developed. Biodegradable amphiphilic block copolymer monomethoxy poly(ethylene glycol)‐b‐Poly(AC) (mPEG‐b‐poly(AC)) with pendant acrylate group was synthesized by means of ring opening polymerization of acryloyl carbonate (AC). Then CCLMs were obtained via thiol‐acrylate Michael addition reaction between the pendant acrylate group in the hydrophobic block and the crosslinker 1,6‐hexanedithiol. DLS results showed that the CCLMs prepared from mPEG‐b‐poly(AC)25 were more stable than uncrosslinked micelles (UCLMs) upon dilution by 10‐fold DMF. Model drug Coumarin 102 was then encapsulated into the micelles. The pH‐responsive release of coumarin 102 from the CCLMs was demonstrated by fluorescence spectroscopy. The core crosslinked polycarbonate micelles have a potential as efficient intracellular smart drug delivery platforms. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44421.

IRGD-Decorated Polymeric Nanoparticles for the Efficient Delivery of Vandetanib to Hepatocellular Carcinoma: Preparation and in Vitro and in Vivo Evaluation.

Molecularly targeted agents that are designed to target specific lesions have been proven effective as clinical cancer therapies; however, most currently available therapeutic agents are poorly water-soluble and require oral administration, thereby resulting in low bioavailability and a high risk of side effects due to dose intensification. The rational engineering of systemically injectable medicines that encapsulate such therapeutic payloads may revolutionize anticancer therapies and remains an under-explored area of drug development. Here, the injectable delivery of a nanomedicine complexed with an oral multitargeted kinase inhibitor, vandetanib (vanib), was explored using polymeric nanoparticles (NPs) to achieve the selective accumulation of drug payloads within tumor lesions. To demonstrate this concept, we used biodegradable amphiphilic block copolymer poly(ethylene glycol)-block-poly(D,L-lactic acid) (PEG-PLA) to nanoprecipitate this potent agent to form water-soluble NPs that are suitable for intravenous administration. NP-vanib induced cytotoxic activity by inhibiting the angiogenetic events mediated by VEGFR and EGFR kinases in tested cancer cells and inhibited the growth, tube formation and metastasis of HUVECs. The intravenously injection of NP-vanib into mice bearing HCC BEL-7402 xenografts more effectively inhibited the tumor than the oral administration of vanib. In addition, due to the modular design of these NPs, the drug-loaded particles can easily be decorated with iRGD, a tumor-homing and -penetrating peptide motif, which further improved the in vivo performance of these vanib-loaded NPs. Our results demonstrate that reformulating targeted therapeutic agents in NPs permits their systemic administration and thus significantly improves the potency of currently available, orally delivered agents.

Finely Tuned Thermo-Responsive Block Copolymer Micelles for Photothermal Effect-Triggered Efficient Cellular Internalization.

Although biodegradable amphiphilic block copolymer micelles have been widely applied in the clinical applications as drug delivery nanocarriers, low-efficiency cellular internalization frequently reduces therapeutic efficacy of the loaded drugs. Here, photothermal effect-promoted cellular internalization of finely tuned thermo-responsive amphiphilic biodegradable block copolymer nanocarriers via noninvasive stimuli of near-infrared (NIR) light irradiation is demonstrated. Amphiphilic block copolymers, poly(ε-caprolactone)-block-poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (PCL-b-P(NIPAM-co-DMA)), are prepared with finely tuned compositions of P(NIPAM-co-DMA) for desirable lower critical solution temperature of the block copolymer micelles in aqueous solution. The block copolymers are then used to co-encapsulate doxorubicin and indocyanine green, which show high encapsulation efficiency and significant photothermal effect upon exposure to NIR light irradiation. The photothermal effect-induced collapse and hydrophilic-to-hydrophobic transition of P(NIPAM-co-DMA) shells significantly enhance the interactions between drug-loaded micelles and cell membranes, which dramatically promote the cellular internalization of the micelles and therapeutic efficacy of loaded anticancer drugs.

Sensitizing nanoparticle based platinum(IV) drugs by curcumin for better chemotherapy

A polymer-cisplatin(IV) conjugate was prepared by attaching Pt(IV)-COOH to a biodegradable amphiphilic block copolymer containing pendant OH groups. The conjugate can assemble into micelles (M(Pt)) with a mean diameter of ca. 169nm. Further, curcumin (CM) was used to sensitize platinum drug based nanoparticles to overcome cisplatin resistance and enhance antitumor efficacy. In vitro studies showed that M(Pt)/CM combinations had great synergistic effect both on cisplatin sensitive and cisplatin resistant cell lines (A2780 and A2780DDP). In vivo studies showed that M(Pt)/CM had a much lower systemic toxicity and an enhanced antitumor efficacy compared to cisplatin alone or the corresponding cisplatin/CM combinations. Therefore, polymer-cisplatin(IV) conjugate with small molecules that serve as a non-cytotoxic or minimally cytotoxic sensitizer or enhancer provide a promising strategy, which may have potential clinical implications in the near future.

PH-sensitive surface charge-conversion nanomicelle for anti-tumor drug delivery

Event Abstract Back to Event pH-sensitive surface charge-conversion nanomicelle for anti-tumor drug delivery Wei Wu1, 2*, Guixue Wang1* and Jianshu Li2* 1 Chongqing University, Bioengineering College, China 2 Sichuan University, College of Polymer Science and Engineering, China Introduction: During the last decade, tremendous efforts have been attained in the development of stimuli-responsive polymeric nanocarriers for the controlled delivery of various anti-cancerous drugs[1]. Physiological stimuli-responsive nanocarriers provide the feasible platforms for cancer therapy due to their improved anticancer efficiency as well as reduced systematic cytotoxicity via the tumor specific enhanced permeability and retention (EPR) effect[2]. It is interesting to note the pH-sensitive surface charge-conversion strategy, which is potential for enhancing tumor cell internalization efficiency. In this study, we attempt to engineer this smart tumor-acidity activated surface charge-conversion function into a biodegradable amphiphilic block copolymers for anticancer application. Materials and Methods: Poly(D, L-lactide)-block-poly(2-aminoethyl methacrylate) (PLA-b-PAEMA, MW 8900, PDI 1,24) was firstly synthesized through ring-opening polymerization (ROP) and subsequently atom transition radical polymerization method. PLA-b-PAEMA/DMMA was obtained by using 2,3-dimethykmaleic anhydride (DMMA) modified PLA-b-PAEMA. Results and Discussion: The well-defined PLA-b-PAEMA is further modified by DMMA and succinic anhydride (SA) to yield the tumor-acidity activated surface charge-conversional block copolymer (PLA-b-PAEMA/DMMA) and the control sample (PLA-b-PAEMA/SA). In this design, the biodegradable PLA block and the functional PAEMA/DMMA (or PAEMA/SA) block provide the amphiphilic driving force to self-assemble into nanocarriers, which have PLA aggregated hydrophobic inner core and PAEMA/DMMA (or PAEMA/SA) outer corona, in aqueous solution. As compared with the invariable negative surface charge of PAEMA/SA block, PAEMA/DMMA block shows the tumor-acidity activated surface charge-conversion feature, i.e., exhibiting negatively charged surface during the blood circulation time and positively charged surface in response to slight tumor acidic environment through the hydrolysis of DMMA functional agents. Thus, after the loading of positively charged doxorubicin hydrochloride (DOX·HCl) into the negatively charged corona structure through electrostatic attraction, the DOX·HCl-loaded PLA-b-PAEMA/DMMA carrier (PLA-b-PAEMA/DMMA@DOX·HCl) is expected to prolong blood circulation time because its “stealthy” negatively charged surface could effectively decrease the undesired consumption by the reticuloendothelial system (RES) and the protein adsorption in vivo, and promote the anti-cancer therapeutic efficiency though the tumor activated positively charged surface for enhanced tumor cell adhesion and targeted drug release (Scheme 1). Scheme1. Illustration of tumor-acidity activated carriers for enhanced cell uptake and targeted drug release. Conclusions: In summary, we construct a smart nanocarrier based on biodegradable PLA-b-PAEMA/DMMA copolymer, which could convert surface charge from negative to positive in response to the tumor-acidity. It exhibits various superiorities for tumor-specific drug delivery, including long blood circulation time, enhanced tumor-cell adhesion, tumor targeted drug release and additional cytotoxicity for tumor cells after the charge-conversion. Thus, this biodegradable smart carrier integrated high drug delivery efficiency and well-improved biocompatibility provides a feasible platform for the ideal anti-tumor therapy. Financial support from the National Natural Science Foundation of China (51322303); Financial support from the Foundations of Sichuan Province (2012JQ0009)

Abstract B40: Concomitant delivery of paclitaxel and NuBCP9 peptide, for the enhancement of synergistic effect, in cancer therapy

Abstract Introduction: Paclitaxel (PTX) is a powerful chemotherapeutic agent that binds to microtubules to prevent tumour cell division. However, a traditional high dose of Paclitaxel may also induce apoptosis in normal cells. NuBCP9, an anticancer peptide (ACP), which selectively binds to the Bcl-2 protein overexpressed almost in all the cancers and convert the anti-apoptotic Bcl-2 to pro-apoptotic and initiate apoptosis. The combination of two or more therapeutic drugs is feasible means to overcome the limitations. Present study explores the synergistic potential of this anticancer peptide in combination with traditional cytotoxic chemotherapeutic drug, to minimize the amount of each drug, for cancer therapy. Method: Drug-containing nanoparticles composed of biodegradable amphiphilic block copolymers of Polylactic acid-polyethylene glycol-polypropylene glycol-polyethylene glycol (PLA-PEG-PPG-PEG, MW = 70K-12K) were synthesized and nanoparticle size was examined. At varying ratios of drugs, loading efficiency and release behaviour was determined. In vitro growth inhibition of these nanoparticle formulations were evaluated in MCF-7 and MDA-MB 231 breast cancer cells by XTT cell proliferation assay, after which IC50 analyses and combination index calculations were conducted. To assess the antitumor effects of nanoparticles in vivo, we treated Balb/c mice bearing established (∼200 mm3) subcutaneous BCL-2-positive Ehrlich syngeneic tumors, intraperitoneally once a week for the duration of three weeks. Results: Developed biodegardable polymeric core-shell nanoparticles were spherical, with an average diameter of ∼90 nm. Both paclitaxel and NuBCP9 peptide loaded favourably in different ratios within nanoparticles. The drug-loaded NPs possessed a better polydispersity (PDI), indicating that they are more readily subject to controlled size distribution. Studies on cellular uptake and drug release from the system demonstrated that both drugs were effectively taken up by the cells and also releases simultaneously for up to 30 days. Combination indices demonstrated that 1:1 ratio of PTX: ACP had the most synergy in both MCF7 and MDA-MB 231 breast cancer cells and IC50 was found to be 30 fold less than the drugs alone in vitro. Significant tumor regression was observed in vivo in combination of PTX-ACP nanoparticles as compared upon single drug administration. Conclusion: Polylactic acid based biodegradable polymeric nanoparticles have the great potential of prolonged delivery of synergistic agents against breast cancer. The synergy shown here permits the use of relatively low concentrations of peptides and drugs to achieve significant anticancer effects in vitro and in vivo. This dose reduction minimizes drug effects on normal cells, enabling an effective apoptosis-mediated anticancer effect without inducing harmful adverse events. Nanoparticle delivery of drugs may also yield enhanced understanding of mechanisms of synergy between molecular-targeted drugs and traditional chemotherapeutics in vivo, resulting in novel and more efficacious treatment regimens. Citation Format: Dikshi Gupta, Sumeet Kapoor, Priyanka Tyagi, Manoj Kumar, Amit Kumar Tyagi, Surender Kharbanda, Harpal Singh. Concomitant delivery of paclitaxel and NuBCP9 peptide, for the enhancement of synergistic effect, in cancer therapy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B40.

Thiadiazole molecules and poly(ethylene glycol)-block-polylactide self-assembled nanoparticles as effective photothermal agents

A new photothermal nano-agent was obtained by the coprecipitation of 2,5-Bis(2,5-bis(2-thienyl)-N-dodecyl pyrrole) thieno[3,4-b][1,2,5] thiadiazole (TPT–TT) and a biodegradable amphiphilic block copolymer, methoxypoly(ethylene glycol)2K-block-poly(D,L-lactide)2K (mPEG2K-PDLLA2K). TPT–TT, a donor–acceptor–donor (D–A–D) type small molecule, with bis(2-thienyl)-N-alkylpyrrole (TPT) as the donor and thieno[3,4-b]thiadiazole (TT) as the acceptor was a strong near infrared (NIR) absorber, which could convert the absorbed light energy into heat. The formation of TPT–TT nanoparticles (TPT–NPs), which possessed high stability in water, was confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). TPT–NPs showed high photothermal conversion efficiency (32%) and excellent photostability and heating reproducibility. The photostability of TPT–TT NPs was much better than that of indocyanine green (ICG), a federal drug administration (FDA) approved NIR dye. Besides, TPT–TT NPs exhibited significant photothermal therapeutic effect toward human cervical carcinoma (HeLa) and human liver hepatocellular carcinoma (HepG2) cells, while no appreciable dark cytotoxicity was observed. These results highlight the potential of TPT–TT NPs as an effective photothermal agent for cancer therapy.

Amphiphilic copolymers with pendent carboxyl groups for high-efficiency loading and controlled release of doxorubicin

In this paper, biodegradable amphiphilic block copolymer based on methoxy poly(ethylene glycol)-b-poly(5-allyloxy-1,3-dioxan-2-one) (mPEG-b-PATMC) was successfully synthesized in bulk using immobilized porcine pancreas lipase (IPPL) as the catalyst. After thiol-ene “click” reactions occur between thiol group of thioglycolic acid and carbon–carbon double bonds of PATMC segments, the pendent carboxyl-modified copolymer mPEG-b-PATMC-g-SCH2COOH was obtained for high-efficiency loading and controlled release of doxorubicin (DOX) to cancer cells. Both the carboxyl-modified and unmodified copolymers could self-assemble to form nano-sized micelles in aqueous solution, while transmission electron microscopy (TEM) observation showed that the micelles dispersed in spherical shape with nano-size before and after DOX loading. Compared with the unmodified copolymer, the pendent carboxyl-modified structure in mPEG-b-PATMC-g-SCH2COOH could markedly enhance the drug-loading capacity and entrapment efficiency via the electrostatic interaction. The in vitro release studies showed more sustained drug release behavior of mPEG-b-PATMC-g-SCH2COOH without an initial burst, which could be further adjusted by the conditions of ionic strength and pH. Confocal laser scanning microscopy (CLSM) indicated efficient cellular uptake of DOX delivered by mPEG-b-PATMC-g-SCH2COOH, while MTT assays also demonstrated potent cytotoxic activity against HeLa cells.