Haijie Han

IR-780 Loaded Phospholipid Mimicking Homopolymeric Micelles for Near-IR Imaging and Photothermal Therapy of Pancreatic Cancer

IR-780 iodide, a near-infrared (near-IR) fluorescent dye, can be utilized as an effective theranostic agent for both imaging and photothermal therapy. However, its lipophilicity limits its further biomedical applications. Herein, we synthesized a phospholipid mimicking amphiphilic homopolymer poly(12-(methacryloyloxy)dodecyl phosphorylcholine) (PMDPC) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The amphiphilic homopolymer PMDPC can be self-assembled into micelles and used for the encapsulation of IR-780. The IR-780 loaded micelles (PMDPC-IR-780) exhibited low cytotoxicity in the dark, whereas remarkable photothermal cytotoxicity to pancreatic cancer cells (BxPC-3) was observed upon near-IR laser irradiation. We further investigated in vivo biodistribution of PMDPC-IR-780 micelles. Higher accumulation of PMDPC-IR-780 than that of free IR-780 in tumor tissue was verified, which might be ascribed to the enhanced permeability and retention (EPR) effect and long circulation time benefiting from the zwitterionic phosphorylcholine surface. Therefore, the IR-780 loaded phospholipid mimicking homopolymeric micelles could have great potential for cancer theranostics.

Light and pH dual-degradable triblock copolymer micelles for controlled intracellular drug release.

A novel amphiphilic ABA-type triblock copolymer poly(ethylene glycol)-b-poly(ethanedithiol-alt-nitrobenzyl)-b-poly(ethylene glycol) (PEG-b-PEDNB-b-PEG) is successfully prepared by sequential thiol-acrylate Michael addition polymerization in one pot. PEG-b-PEDNB-b-PEG is designed to have light-cleavable o-nitrobenzyl linkages and acid-labile β-thiopropionate linkages positioned repeatedly in the main chain of the hydrophobic block. The light and pH dual degradation of PEG-b-PEDNB-b-PEG is traced by gel permeation chromatography (GPC). Such triblock copolymer can self-assemble into micelles, which can be used to encapsulate anticancer drug doxorubicin (DOX). Because of the different degradation chemistry of o-nitrobenzyl linkages and β-thiopropionate linkages, DOX can be released from the micelles by two different manners, i.e., light-induced rapid burst release and pH-induced slow sustained release. Confocal laser scanning microscopy (CLSM) results indicated that DOX-loaded micelles exhibited faster drug release in A549 cells after UV irradiation. Furthermore, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) results show that the DOX-loaded micelles under UV light degradation exhibit better anticancer activity against A549 cells than that of the nonirradiated ones.

pH- and NIR Light-Responsive Polymeric Prodrug Micelles for Hyperthermia-Assisted Site-Specific Chemotherapy to Reverse Drug Resistance in Cancer Treatment.

Despite the exciting advances in cancer chemotherapy over past decades, drug resistance in cancer treatment remains one of the primary reasons for therapeutic failure. IR-780 loaded pH-responsive polymeric prodrug micelles with near infrared (NIR) photothermal effect are developed to circumvent the drug resistance in cancer treatment. The polymeric prodrug micelles are stable in physiological environment, while exhibit fast doxorubicin (DOX) release in acidic condition and significant temperature elevation under NIR laser irradiation. Phosphorylcholine-based biomimetic micellar shell and acid-sensitive drug conjugation endow them with prolonged circulation time and reduced premature drug release during circulation to conduct tumor site-specific chemotherapy. The polymeric prodrug micelles combined with NIR laser irradiation could significantly enhance intracellular DOX accumulation and synergistically induce the cell apoptosis in DOX-resistant MCF-7/ADR cells. Meanwhile, the tumor site-specific chemotherapy combined with hyperthermia effect induces significant inhibition of MCF-7/ADR tumor growth in tumor-bearing mice. These results demonstrate that the well-designed IR-780 loaded polymeric prodrug micelles for hyperthermia-assisted site-specific chemotherapy present an effective approach to reverse drug resistance.

Zwitterionic Phosphorylcholine–TPE Conjugate for pH-Responsive Drug Delivery and AIE Active Imaging

Polymeric micelles have emerged as a promising nanoplatform for cancer theranostics. Herein, we developed doxorubicin (DOX) encapsulated pH-responsive polymeric micelles for combined aggregation induced emission (AIE) imaging and chemotherapy. The novel zwitterionic copolymer poly(2-methacryloyloxyethylphosphorylcholine-co-2-(4-formylphenoxy)ethyl methacrylate) (poly(MPC-co-FPEMA)) was synthesized via RAFT polymerization and further converted to PMPC-hyd-TPE after conjugation of tetraphenylethene (TPE, a typical AIE chromophore) via acid-cleavable hydrazone bonds. The AIE activatable copolymer PMPC-hyd-TPE could self-assemble into spherical PC-hyd-TPE micelles, and DOX could be loaded through hydrophobic interactions. The zwitterionic micelles exhibited excellent physiological stability and low protein adsorption due to the stealthy phosphorylcholine (PC) shell. In addition, the cleavage of hydrophobic TPE molecules under acidic conditions could induce swelling of micelles, which was verified by size changes with time at pH 5.0. The in vitro DOX release profile also exhibited accelerated release rate with pH value decreasing from 7.4 to 5.0. Fluorescent microscopy and flow cytometry studies further demonstrated fast internalization and accumulation of drug loaded PC-hyd-TPE-DOX micelles in HepG2 cells, resulting in considerable time/dose-dependent cytotoxicity. Meanwhile, high-quality AIE imaging of PC-hyd-TPE micelles was confirmed in HepG2 cells. Notably, ex vivo imaging study exhibited efficient accumulation and drug release of PC-hyd-TPE-DOX micelles in the tumor tissue. Consequently, the multifunctional micelles with combined nonfouling surface, AIE active imaging, and pH-responsive drug delivery showed great potential as novel nanoplatforms for a new generation of cancer theranostics.

The rational design of a gemcitabine prodrug with AIE-based intracellular light-up characteristics for selective suppression of pancreatic cancer cells.

An enzyme and reduction-activatable gemcitabine prodrug (TPE-GEM-RGD) with aggregation-induced emission (AIE) properties was designed for targeted and image-guided cancer therapy. TPE-GEM-RGD was successfully used for intracellular light-up imaging and glutathione (GSH)-responsive release of gemcitabine to suppress pancreatic cancer cells.

Design and Proof of Programmed 5-Aminolevulinic Acid Prodrug Nanocarriers for Targeted Photodynamic Cancer Therapy

5-Aminolevulinic acid (ALA), the precursor of photosensitizer protoporphyrin IX (PpIX), is a U.S. FDA-approved photodynamic therapeutic agent. However, realizing efficient delivery of ALA is still a big challenge as it is hydrophilic and cannot be recognized and selectively accumulated in tumor cells. In this study, matrix metalloproteinase-2 (MMP-2) and pH dual-sensitive ALA prodrug nanocarriers were constructed as a programmed delivery strategy for the targeted delivery of ALA. The nanocarriers were prepared by the co-modification of gold nanoparticles (AuNPs) with hydrazone-linked ALA and MMP-2-activatable cell-penetrating peptides (CPPs). Cationic CPP RRRRRRRR (R8) was shielded by zwitterionic stealth peptide EKEKEKEKEKEKEKEKEKEK (EK10) via MMP-2 substrate peptide PLGLAG. The zwitterionic stealth peptide EK10 is designed to endow ALA prodrug nanocarriers with strong antifouling ability and prolonged circulation time. Upon arriving at the tumor tissue, the shielded cationic CPP R8 can be activated by tumor-microenvironment-overexpressed MMP-2, which enabled enhanced cellular uptake of ALA. The results of drug loading and release, cellular uptake, PpIX generation and accumulation, photodynamic cytotoxicity, and photodynamic tumor inhibition demonstrated that such tumor-microenvironment-sensitive ALA prodrug nanocarriers could be considered as potential candidates for targeted photodynamic cancer therapy.

Intracellular Dual Fluorescent Lightup Bioprobes for Image-Guided Photodynamic Cancer Therapy.

An intracellular dual fluorescent light-up bioprobe with aggregation-induced emission features and endogenously producing photosensitizer protoporphyrin IX (PpIX) abilities is designed and synthesized. The bioprobe is nonemissive in physiological environment. However, the bioprobe can selectively light up cancer cells with blue fluorescence of tetraphenylene (TPE) and red fluorescence of PpIX, owing to the release of TPE and methyl aminolevulinate after targeted internalization by cancer cells. Moreover, upon endogenous generation and accumulation of PpIX in cancer cells, efficient photodynamic ablation of cancer cells after light irradiation is demonstrated with easy regulation for optimal therapeutic efficacy. The design of such dual fluorescent light-up bioprobes might provide a new opportunity for targeted and image-guided photodynamic cancer therapy.

Polyamino acid-based gemcitabine nanocarriers for targeted intracellular drug delivery

In the present study, we have successfully fabricated a biocompatible polyamino acid-based nanocarrier with reduction-sensitivity and targeting ability for gemcitabine (GEM) delivery. GEM-conjugated polyamino acid biotin-poly(ethylene glycol)-block-poly[(L-lysine-co-L-leucine)-graft-(GEM-co-rhodamine B)] (Biotin-PEG-b-P[(Lys-co-Leu)-graft-(GEM-co-Rho B)]) was synthesized by ring-opening copolymerization of L-lysine-N-carboxyanhydride (Lys-NCA) and L-leucine-N-carboxyanhydride (Leu-NCA) using biotin-poly(ethylene glycol)-amine (Biotin-PEG-NH2) as an initiator, and then disulfide linked GEM derivatives (HSEA-GEM) and Rhodamine B isothiocyanate (Rho B) were grafted onto polyamino acids. The obtained GEM-conjugated polyamino acids could self-assemble into nano-sized micelles in aqueous solution with a uniform spherical shape. The GEM nanocarriers showed reduction-sensitive drug release. Cell culture demonstrated that the polyamino acid itself showed excellent biocompatibility but high cytotoxicity when conjugated with GEM. Whats more, the biotin-conjugated polyamino acid-based micelles could induce a remarkably higher internalization via receptor mediated endocytosis than non-biotin micelles. Hence, such biocompatible GEM-conjugated polyamino acids might provide a potential strategy for cancer therapy.