Polymer nanoparticles regulate macrophage repolarization for antitumor treatment

We demonstrate an intrinsic antitumor effect of polymer nanoparticles (P-NPs), which could re-program tumor-associated macrophages to pro-inflammatory phenotype. The intrinsic effect of P-NPs on macrophage repolarization and its combination with other therapies provide new ideas for drug delivery, macrophage regulation and immunotherapy in cancer treatment.

Antibody Conjugation of Nanoparticles as Therapeutics for Breast Cancer Treatment

Breast cancer is the most common invasive tumor in women and the second leading cause of cancer-related death. Nanomedicine raises high expectations for millions of patients as it can provide better, more efficient, and affordable healthcare, and it has the potential to develop novel therapeutics for the treatment of solid tumors. In this regard, targeted therapies can be encapsulated into nanocarriers, and these nanovehicles are guided to the tumors through conjugation with antibodies-the so-called antibody-conjugated nanoparticles (ACNPs). ACNPs can preserve the chemical structure of drugs, deliver them in a controlled manner, and reduce toxicity. As certain breast cancer subtypes and indications have limited therapeutic options, this field provides hope for the future treatment of patients with difficult to treat breast cancers. In this review, we discuss the application of ACNPs for the treatment of this disease. Given the fact that ACNPs have shown clinical activity in this clinical setting, special emphasis on the role of the nanovehicles and their translation to the clinic is placed on the revision.

Intrinsically ESIPT-exhibiting and enhanced emission in polymer nanoparticles as signaling for sensing nitrite

A straightforward approach to the fabrication of intrinsically excited-state intramolecular proton transfer (ESIPT)-fluorescent polymer nanoparticles (e-PNPs) was developed. The e-PNPs were obtained by self-assembly of the homopolymers derived from 4-aminosalicylic acid in aqueous solution. By incorporating ESIPT modules into polymer nanoparticles, the ESIPT reaction can be endowed with moderate hydrophobic micro-environment by nanoparticle scaffolds, eliciting enhanced ESIPT emission. The newly developed e-PNPs exhibit strong tautomeric fluorescence(e-FL), good photostability, low-toxicity and favourable biocompatibility in aqueous solution. Upon the addition of NO₂^-, the e-FL can be significantly quenched owing to the reaction of NO₂^- with the amide groups on e-PNPs. From this basis, the fluorescence detection of NO₂^- was implemented, which showed a linear relationship between 0 nM and 110 nM with a detection limit of 2.3 nM. Furthermore, e-PNPs were used as nanoprobes to monitor the NO₂^- levels in HeLa cells by fluorescence imaging, demonstrating the ability of discrimination from different concentrations of NO₂^-. The proposed method can be applied to a wide range of other ESIPT modules to integrate into polymer nanoparticles and offer highly sensitive nanosensing platform for bioanalysis and molecular imaging.

Synthesis and biological evaluation of redox/NIR dual stimulus-responsive polymeric nanoparticles for targeted delivery of cisplatin

Functional drug delivery systems enabling various favorable characteristics including specific targets, efficient cellular uptake and controllable release. At present work, a folate and cRGD dual modified nanoparticles based on NIR light and glutathione dual stimuli-responsive release system was successfully prepared and which simultaneously deliver cisplatin and ICG to tumor sites to enhance controllability. The prepared nanoparticles showed a stable uniform spherical morphology of 77.59 nm particle size range in PBS (pH = 7.4, 25 °C) and the encapsulated cisplatin were rapidly released in acidic environment especially added glutathione (GSH) and NIR irradiation. Moreover, the prepared nanoparticles can be efficiently internalized by tumor cells through the enhanced dual targeted ligands (folate and cRGD) for ICG imaging. The cytotoxicity assays showed that the cells viability decreased to 1.95% (SGC-7901) when been exposed to NIR light, and which further decreased to 1.25% in MCF-7 cells. Thus, the prepared nanoparticles showed excellent performance for photothermal conversion therapy of tumor cells and especially on human breast tumor cells. Our research highlights the great potential of stimuli-responsive smart nanoparticles in biomaterial and nano-biomedicine.

Folate-Conjugated Polyphosphoester with Reversible Cross-Linkage and Reduction Sensitivity for Drug Delivery

To improve the therapeutic efficacy and circulation stability in vivo, we synthesized a new kind of drug delivery carrier based on folic acid conjugated polyphosphoester via the combined reactions of Michael addition polymerization and esterification. The produced amphiphilic polymer, abbreviated as P(EAEP-AP)-LA-FA, could self-assemble into nanoparticles (NPs) with core-shell structure in water and reversible core cross-linked by lipoyl groups. Using the core cross-linked FA-conjugated nanoparticles (CCL-FA NPs) to encapsulate hydrophobic anticancer drug doxorubicin (DOX), we studied the stability of NPs, in vitro drug release, cellular uptake, and targeting intracellular release compared with both un-cross-linked FA-conjugated nanoparticles (UCL-FA NPs) and core cross-linked nanoparticles without FA conjugation (CCL NPs). The results showed that under the condition of pH 7.4, the DOX-loaded CCL-FA NPs could maintain stable over 72 h, and only a little DOX release (∼15%) was observed. However, under the reductive condition (pH 7.4 containing 10 mM GSH), the disulfide-cross-linked core would be broken up and resulted in 90% of DOX release at the same incubation period. The study of methyl thiazolyl tetrazolium (MTT) assay indicated that the DOX-loaded CCL-FA NPs exhibited higher cytotoxicity (IC₅₀: 0.33 mg L^-1) against HeLa cells than the DOX-loaded CCL NPs without FA. These results indicate that the core cross-linked FA-conjugated nanoparticles have unique stability and targetability.

Folate-decorated PEGylated triblock copolymer as a pH/reduction dual-responsive nanovehicle for targeted intracellular co-delivery of doxorubicin and Bcl-2 siRNA

Co-delivery of chemotherapeutic drug and small interfering RNA (siRNA) within a single nanovehicle has emerged as a promising combination therapy approach to treating cancers because of their synergistic effect. Nanocarrier delivery systems with low cytotoxicity and high efficiency are needed for such a purpose. In this study, a novel folate-conjugated PEGylated cationic triblock copolymer, poly(acrylhydrazine)-block-poly(3-dimethylaminopropyl methacrylamide)-block-poly(acrylhydrazine) (PAH-b-PDMAPMA-b-PAH), was synthesized and evaluated as a stimuli-sensitive vehicle for the targeted co-delivery of doxorubicin (DOX) and Bcl-2 siRNA into breast cancer MCF-7 cells. The synthetic process of the PEGylated triblock copolymer involved sequential reversible addition-fragmentation chain transfer polymerization, PEGylation and removal of tert-butoxy carbamate protecting groups. Folate-conjugated and/or -unconjugated poly(ethylene glycol) segments were grafted onto PAH-b-PDMAPMA-b-PAH via a reduction-sensitive disulfide linkage. The synthetic polymers were characterized by ¹H NMR and gel permeation chromatography. The PEGylated triblock copolymer could chemically conjugate DOX onto PAH blocks via pH-responsive hydrazone bonds and simultaneously complex negatively charged Bcl-2 siRNA with cationic PDMAPMA blocks through electrostatic interactions at N/P ratios≥32:1 to form multifunctional nanomicelleplexes. The nanomicelleplexes exhibited spherical shape, possessed a positively charged surface with a zeta potential of +22.5mV and had a desirable and uniform particle size of 187nm. In vitro release studies revealed that the nanomicelleplexes could release DOX and Bcl-2 siRNA in a reduction and pH dual-sensitive manner and the payload release was significantly enhanced in a reductive acidic environment mimicking the endosomes/lysosomes of cancer cells compared to under physiology conditions. Furthermore, the release of both DOX and siRNA was found to follow Higuchi kinetic model. Confocal laser scanning microscopy, flow cytometry and MTT analyses confirmed that, compared with folate-undecorated nanomicelleplexes, folate-decorated nanomicelleplexes could more effectively co-deliver DOX and Bcl-2 siRNA into MCF-7 cells and showed a stronger cell-killing effect. The pristine PEGylated triblock copolymer exhibited good cytocompatibility. Moreover, co-delivery of DOX and Bcl-2 siRNA achieved a significant synergistic antitumor efficacy. These findings suggested that the folate-decorated PEGylated cationic triblock copolymer might be a promising vehicle for targeted intracellular co-delivery of DOX and siRNA in MCF-7 cells, representing a potential clinical combination therapy for breast cancer treatment.

Combinatorial delivery of superparamagnetic iron oxide nanoparticles (γFe2O3) and doxorubicin using folate conjugated redox sensitive multiblock polymeric nanocarriers for enhancing the chemotherapeutic efficacy in cancer cells

Redox sensitive, folate conjugated multiblock polymeric system of (-PLGA-PEG-PLGA-urethane-ss-) demonstrated self-assembly into stable nanoplatforms. The polymeric nanocarriers were encapsulated with doxorubicin and highly crystalline γFe₂O₃ superparamagnetic iron oxide nanoparticles (SPIONs), for co-delivery of the same to cancer cells, with average particle size of ~170nm and zeta potential of ~-33mV. Furthermore, the designed formulation was evaluated for protein adsorption, hemo-cytocompatibility and stability. Glutathione (GSH) induced redox sensitivity of the nanocarriers was depicted by ~4.47 fold increase in drug release in the presence of 10mM GSH. In vitro cellular uptake studies of the designed nanocarriers showed synergistic cytotoxic effect in folate overexpressing cells (HeLa and MDA-MB-231), after subjecting the cells to radio frequency (RF) induced hyperthermia (~43°C). Negligible effect of the combinatorial therapy was observed in normal cells (L929). The developed polymeric system depicted facile synthesis, reproducibility and potential for achieving combinatorial and targeted delivery of drug and SPIONs to cancer cells. This combinatorial approach can help in achieving better therapeutic effect with minimal side effects of chemotherapy.

Synthesis and micellization of redox-responsive dynamic covalent multi-block copolymers

Multi-block copolymers, which are composed of two or more covalent interconnected polymeric segments of different types, offer unparalleled opportunities for designing new nanostructured materials with enhanced functionality and properties.