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

ROS-Responsive Polymeric Nanocarriers with Photoinduced Exposure of Cell-Penetrating Moieties for Specific Intracellular Drug Delivery

In situ modulation of the surface properties on the micellar drug delivery nanocarriers offers an efficient method to improve the drug delivery efficiency into cells while maintaining stealth and stability during blood circulation. Light has been demonstrated to be a temporally and spatially controllable tool to improve cellular internalization of nanoparticles. Herein, we develop reactive oxygen species (ROS)-responsive mixed polymeric micelles with photoinduced exposure of cell-penetrating moieties via photodynamic ROS production, which can facilitate cellular internalization of paclitaxel (PTX) and chlorin e6 (Ce6)-coloaded micelles for the synergistic effect of photodynamic and chemotherapy. The thioketal-bond-linked block polymers poly(ε-caprolactone)-TL-poly(N,N-dimethylacrylamide) (PCL-TL-PDMA) with a long PDMA block are used to self-assemble into mixed micelles with PCL-b-poly(2-guanidinoethyl methacrylate) (PCL-PGEMA) consisting of a short PGEMA block, which are further used to coencapsulate PTX and Ce6. After intravenous injection, prolonged blood circulation of the micelles guarantees high tumor accumulation. Upon irradiation by 660 nm light, ROS production of the micelles by Ce6 induces cleavage of PDMA to expose PGEMA shells for significantly improved cellular internalization. The combination of photodynamic therapy and chemotherapy inside the tumor cells achieves improved antitumor efficacy. The design of ROS-responsive mixed polymeric nanocarriers represents a novel and efficient approach to realize both long blood circulation and high-efficiency cellular internalization for combined photodynamic and chemotherapy under light irradiation.

Sorafenib and indocyanine green co-loaded in photothermally sensitive liposomes for diagnosis and treatment of advanced hepatocellular carcinoma

Sorafenib (SF), as an irreplaceable first-line drug to help advanced hepatocellular carcinoma (HCC) patients to prolong their lives, has already been used in clinical practice for several years. However, this treatment causes several side effects, and few alternatives to SF treatment exist. Herein, we designed NIR fluorescence imaging-guided photothermally sensitive nanoliposomes based on co-encapsulation of SF and the clinical photothermal and photodynamic therapy agent Indocyanine Green (ICG) to solve the problems of SF-based treatment in advanced HCC. As expected, in vitro and in vivo drug release studies on SF-ICG liposomes (SILs) demonstrated SF release from SILs compared with free SF at the same concentration. In addition, in vivo NIR fluorescence imaging and anti-tumor treatment using SILs have been demonstrated by using Hep3B tumor-bearing xenograft nude mice. All detailed experimental evidence suggested that biocompatibility, biotoxicity, and anti-tumor effects were improved by using SILs instead of free SF. In conclusion, our designed SILs could present a novel and suitable SF-based treatment strategy for advanced HCC therapy in the future.

Thermoresponsive and Biodegradable Amphiphilic Block Copolymers with Pendant Functional Groups

BACKGROUND

To develop the biodegradability and thermoresponsive hydrogel, in this work we designed a pendant-functionalized, thermoresponsive, amphiphilic block copolymer.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Theranostic Nanoplatform: Triple-Modal Imaging-Guided Synergistic Cancer Therapy Based on Liposome-Conjugated Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNs) have long since been investigated to provide a versatile drug-delivery platform due to their multitudinous merits. Presently, gadolinium (Gd), a T1 magnetic resonance imaging (MRI) contrast agent, was doped into MSNs as a newly emerging theranostic nanocomposite, which has received much research attention. However, it is still concerned about the dispersibility and drug leakage of MSNs. Hence, in this project, we constructed an near-infrared (NIR) irradiation-triggered, triple-modal imaging-guided nanoplatform based on doxorubicin (DOX)@Gd-doped MSNs, conjugating with indocyanine green (ICG)-loaded thermosensitive liposomes (designated as DOX@GdMSNs-ICG-TSLs). In this platform, ICG could contribute to both photodynamic therapy and photothermal therapy effects; meanwhile, it could also give play to near-infrared fluorescence imaging (NIRFI) as well as photoacoustic imaging (PAI). Consequently, NIRFI and PAI from ICG combined with the MRI function of Gd, devoted to triple-modal imaging with success. At the same time, folic acid-modified thermosensitive liposomes were explored to be coated onto the surface of DOX@GdMSNs, to solve the DOX leakage as well as improve cellular uptake. Under NIR irradiation, ICG could generate heat, thus leading to the rupture of ICG-TSLs and the release of DOX. Accordingly, the multifunctional nanocomposite appeared to be a promising meritorious theranostic nanoplatform to pave a way for treating cancer.

Self-assembled amphiphilic core-shell nanocarriers in line with the modern strategies for brain delivery

Disorders of the central nervous system (CNS) represent increasing social and economic problems all over the world which makes the effective transport of drugs to the brain a crucial need. In the last decade, many strategies were introduced to deliver drugs to the brain trying to overcome the challenge of the blood brain barrier (BBB) using both invasive and non-invasive methods. Non-invasive strategy represented in the application of nanocarriers became very common. One of the most hopeful nanoscopic carriers for brain delivery is core-shell nanocarriers or polymeric micelles (PMs). They are more advantageous than other nanocarriers. They offer small size, ease of preparation, ease of sterilization and the possibility of surface modification with various ligands. Hence, the aim of this review is to discuss modern strategies for brain delivery, micelles as a successful delivery system for the brain and how micelles could be modified to act as "magic bullets" for brain delivery.