Cancer-associated pH-responsive tetracopolymeric micelles composed of poly(ethylene glycol)-b-poly(L-histidine)-b-poly(L-lactic acid)-b-poly(ethylene glycol)

Folate-decorated redox/pH dual-responsive degradable prodrug micelles for tumor triggered targeted drug delivery

Multifunctional polymeric prodrug micelles, which allow the targeted intracellular delivery and facilitated release of conjugated drugs at cytoplasm in response to an intracellular glutathione and pH level, were developed.

Hoechst 33258–conjugated hyaluronated fullerene for efficient photodynamic tumor therapy and necrotic tumor targeting

In this study, we synthesized a Hoechst 33258–conjugated hyaluronated fullerene consisting of Hoechst 33258 (as a target moiety to detect necrotic tumor cells), hyaluronic acid (as a target polymer to bind the CD44 receptor overexpressed on the surface of tumor cells), and fullerene (as a photosensitizing agent). This conjugate self-assembled to form nanoparticles consisting of a hydrophilic block (Hoechst 33258 and hyaluronic acid) and a lipophilic block (fullerene). We utilized these nanoparticles to improve the antitumor efficacy via photodynamic tumor therapy. The HCT-116 cells that were damaged after the first photodynamic tumor therapy (using hyaluronated fullerene nanoparticles) were again targeted using Hoechst 33258–conjugated hyaluronated fullerene nanoparticles (detecting necrotic tissues). The experimental results revealed that the second photodynamic tumor therapy using Hoechst 33258–conjugated hyaluronated fullerene nanoparticles caused significant increases in the in vitro phototoxicity and the in vivo tumor inhibition, thereby suggesting their pharmaceutical potential for designing effective multiple photodynamic tumor therapy treatments.

Folate-decorated polymeric Pt(ii) prodrug micelles for targeted intracellular delivery and cytosolic glutathione-triggered release of platinum anticancer drugs

Bioreducible FA-PEG-b-P(α-Pt(ii)-SS-CL/CL) conjugates have been successfully developed in order to build redox-responsive micelles with targeting and site-specific drug releasing abilities.

Controlled polymerization of histidine and synthesis of well-defined stimuli responsive polymers. Elucidation of the structure–aggregation relationship of this highly multifunctional material

Synthesis of multifunctional poly(l-histidine) containing polypeptides and hybrid polymers for controlled drug delivery applications.

Self-assemblies of triskelion A2B-type amphiphilic polypeptide showing pH-responsive morphology transformation

A pH-responsive rolled-sheet morphology was prepared from a triskelion A(2)B-type amphiphilic polypeptide having a histidine residue as a pH-responsive unit. The dimensions of the rolled sheet were 85 nm diameter and 210 nm length with a sheet turn number of 2.0 at pH 7.4. Upon decreasing the pH from 7.4 to 5.0, the layer spacing of the rolled sheets was widened from ca. 9 to ca. 19 nm due to electrostatic repulsion caused by histidine protonation. This morphology change occurred reversibly with a pH change between 7.4 and 5.0. The molecular packing in the rolled sheets was shown to be loosened at pH 5.0 on the basis of electron diffraction measurements. The tightness of the rolled sheets was thus controlled reversibly by a pH change due to a single protonation in the amphiphilic polypeptide.

Stimuli-sensitive synthetic polypeptide-based materials for drug and gene delivery

Stimuli-sensitive synthetic polypeptides are unique biodegradable and biocompatible synthetic polymers with structures mimicking natural proteins. These polymers exhibit reversible secondary conformation transitions and/or hydrophilic-hydrophobic transitions in response to changes in environmental conditions such as pH and temperature. The stimuli-triggered conformation and/or phase transitions lead to unique self-assembly behaviors, making these materials interesting for controlled drug and gene delivery applications. Therefore, stimuli-sensitive synthetic polypeptide-based materials have been extensively investigatid in recent years. Various polypeptide-based materials, including micelles, vesicles, nanogels, and hydrogels, have been developed and tested for drug- and gene-delivery applications. In addition, the presence of reactive side groups in some polypeptides facilitates the incorporation of various functional moieties to the polypeptides. This Review focuses on recent advances in stimuli-sensitive polypeptide-based materials that have been designed and evaluated for drug and gene delivery applications. In addition, recent developments in the preparation of stimuli-sensitive functionalized polypeptides are discussed.

Scope of nanotechnology in ovarian cancer therapeutics

This review describes the use of polymer micelle nanotechnology based chemotherapies for ovarian cancer. While various chemotherapeutic agents can be utilized to improve the survival rate of patients with ovarian cancer, their distribution throughout the entire body results in high normal organ toxicity. Polymer micelle nanotechnology aims to improve the therapeutic efficacy of anti-cancer drugs while minimizing the side effects. Herein, different types of polymer micelle technology based nanotherapies such as PLGA, polymerosomes, acid cleavable, thermosensitive, pH sensitive, and cross-linked micelles are introduced and structural differences are explained. Additionally, production methods, stability, sustainability, drug incorporation and drug release profiles of various polymer micelle based nanoformulations are discussed. An important feature of polymer micelle nanotechnology is the small size (10-100 nm) of particles which improves circulation and enables superior accumulation of the therapeutic drugs at the tumor sites. This review provides a comprehensive evaluation of different types of polymer micelles and their implications in ovarian cancer therapeutics.

pH-sensitive properties of surface charge-switched multifunctional polymeric micelle

A surface charge-switched polymeric micelle with a pH signal was developed as a drug-carrying nanovehicle for tumor targeting. The micelles (particle size: approximately 85 nm), constructed from poly(L-lactic acid)-b-poly(ethylene glycol)-b-poly(L-lysine-N(epsilon)-(2,3-dimethyl maleic acid)) (PLA-b-PEG-b-PLys-DMA) and formed by self-assembly in an aqueous pH 7.4 solution, consisted of a hydrophobic core (PLA core) and two hydrophilic shells (PEG shell and PLys-DMA shell). An anionic charge can be built on the surface of the micelle at a physiological pH (approximately pH 7.4) due to 2,3-dimethyl maleic acid (DMA). However, DMA becomes chemically dissociated from the micelle under mild acidic conditions (pH 6.5-7.0) such as that found in solid tumors, which results in the formation of a cationic surface due to the poly(L-lysine) (PLys). This pH-triggered switch in surface charge may enhance cellular uptake of micelles to solid tumors, via an adsorptive endocytotic pathway due to the electrostatic interaction between micelles and cells. In addition, blending of the poly(L-histidine) (polyHis) into the hydrophobic core provides a mechanism for endosomal pH-triggered drug-release from the polymeric micelle. These combined properties of the polymeric micelle may aid in tumor-specific drug accumulation and allow it to be used as an effective treatment for tumors.