Core-shell structured nanoassemblies based on β-cyclodextrin containing block copolymer and poly(β-benzyl L-aspartate) via host-guest complexation

Provitamin supramolecular polymer micelle with pH responsiveness to control release, bioavailability enhancement and potentiation of cytotoxic efficacy

Encapsulation techniques to generate core/shell systems provide a method that improves physicochemical properties, which are very important in biological applications. β-carotene is a common carotenoid that has shown preventive effects in skin diseases and vitamin A deficiency but this compound has limited water solubility and bioavailability, which hinder its broad application. The use of polyrotaxane compounds formed from cyclodextrins has allowed supramolecular polymer micelles (SMPMs) to be synthesized to encapsulate β-carotene. The polymeric compound Pluronic F127^® was also used to create core/shell nanoparticles (NPs) that contain β-carotene. Bioactive compound encapsulation was fully confirmed by nuclear magnetic resonance spectroscopy and by scanning and transmission electron microscopy. The method based on cyclodextrin and lecithin allow to release slowly when the systems were exposed to an aqueous medium by pH control, with an increase of 16 times of bioavailability comparing with free carotenoid. This allowed to potentiate the cytotoxic activity on a melanoma cell line by enhancing the water solubility to more than 28 mg/L, and present promising applications of SMPMs to provitamins.

Self-assembly of affinity-controlled nanoparticles via host-guest interactions for drug delivery

There has been increasing interest in constructing affinity-based drug delivery systems via different non-covalent interactions. Herein we report a host-guest interaction-based strategy to develop effective drug delivery systems using cyclodextrin-containing copolymers. Hydrophilic copolymers with one polyethylene glycol block and another block containing either α-cyclodextrin or β-cyclodextrin were synthesized. Using poly(β-benzyl l-aspartate) and pyrene as model guest compounds, we demonstrated the nanoparticle formation by host-guest interaction-mediated self-assembly. When an antioxidant and anti-inflammatory drug Tempol was used, the formation of well-defined spherical nanoparticles and therapeutic loading can be simultaneously realized. The obtained nanotherapy showed affinity-controlled drug release. In vitro cell culture experiments suggested that the host-guest nanotherapy exhibited desirable antioxidant and anti-inflammatory effects in macrophages. In a mouse model of an inflammatory disease ulcerative colitis, the orally administered host-guest nanoparticle can be effectively accumulated in the inflamed colonic tissue. Oral treatment of mice bearing colitis with the nanotherapy led to significantly improved efficacy in comparison with free drugs. A good in vivo safety profile was also observed for the developed host-guest nanotherapy. Accordingly, these types of affinity nanoparticles based on CD-containing copolymers can function as effective nanoplatforms for targeted treatment of a plethora of diseases.

PEG-coumarin nanoaggregates as π-π stacking derived small molecule lipophile containing self-assemblies for anti-tumour drug delivery

Polymeric self-assemblies formed by non-covalent interactions such as hydrophobic interactions, hydrogen bonding, π-π stacking, host-guest and electrostatic interactions have been utilised widely and exhibit controlled release of encapsulated drug. Beside carrier-carrier interactions, small molecule amphiphiles exhibiting carrier-drug interactions have recently been an area of interest for cancer drug delivery, as most of the hydrophobic anti-tumour drugs are aromatic and exhibit π-π conjugated structure. In the present study PEG-coumarin (PC) conjugates forming self-assembled nanoaggregates were synthesised with PEG (polyethylene glycol) as hydrophilic block and coumarin as small molecule lipophilic segment. Curcumin (CUR) as model conjugated aromatic drug was loaded in to the nanoaggregates via dual hydrophobic and π-π stacking interactions. The interactions between the conjugates and CUR, drug release profile and in vitro anti-tumour efficacy were investigated in detail. CUR-loaded nanoaggregate self-assembly was driven by π-π interactions and a maximum loading level of about 18 wt.% (~60 % encapsulation efficiency) was achieved. The average hydrodynamic diameter (D_av) was in the range of 120-160 nm and a spherical morphology was observed by transmission electron microscopy (TEM). A sustained release of CUR was observed for 90 h. Cytotoxicity evaluation of CUR-loaded nanoaggregates on pancreatic cancer cell lines indicated higher efficacy, IC₅₀ ~11 and ~15 μM as compared to free CUR, IC₅₀ ~14 and ~20 μM on human pancreatic carcinoma (MIA PaCa-2) and human pancreatic duct epithelioid carcinoma (PANC-1) cell lines respectively. PC conjugates provided a new strategy of fabricating nanoparticles for drug delivery and may form the basis for the development of advanced biomaterials in near future.

Inclusion complex from cyclodextrin-grafted hyaluronic acid and pseudo protein as biodegradable nano-delivery vehicle for gambogic acid

β-Cyclodextrin can form inclusion complex with a series of guest molecules including phenyl moieties, and has gained considerable popularity in the study of supramolecular nanostructure. In this study, a biodegradable nanocomplex (HA(CD)-4Phe4 nanocomplex) was developed from β-cyclodextrin grafted hyaluronic acid (HA) and phenylalanine based poly(ester amide). The phenylalanine based poly(ester amide) is a biodegradable pseudo protein which provides the encapsulation capacity for gambogic acid (GA), a naturally-derived chemotherapeutic which has been effectively employed to treat multidrug resistant tumor. The therapeutic potency of free GA is limited due to its poor solubility in water and the lack of tumor-selective toxicity. The nanocomplex carrier enhanced the solubility and availability of GA in aqueous media, and the HA component enabled the targeted delivery to tumor cells with overexpression of CD44 receptors. In the presence of hyaluronidase, the release of GA from the nanocomplex was significantly accelerated, due to the enzymatic biodegradation of the carrier. Compared to free GA, GA-loaded nanocomplex exhibited improved cytotoxicity in MDA-MB-435/MDR multidrug resistant melanoma cells, and induced enhanced level of apoptosis and mitochondrial depolarization, at low concentration of GA (1-2µM). The nanocomplex enhanced the therapeutic potency of GA, especially when diluted in physiological environment. In addition, suppressed matrix metalloproteinase activity was also detected in MDA-MB-435/MDR cells treated by GA-loaded nanocomplex, which demonstrated its potency in the inhibition of tumor metastasis. The in vitro data suggested that HA(CD)-4Phe4 nanocomplex could provide a promising alternative in the treatment of multidrug resistant tumor cells.

STATEMENT OF SIGNIFICANCE

Gambogic acid (GA), naturally derived from genus Garcinia trees, exhibited significant cytotoxic activity against multiple types of tumors with resistance to traditional chemotherapeutics. Unfortunately, the poor solubility of GA in conventional pharmaceutical solvents and non-targeted distribution in normal tissues greatly limited its therapeutic potency. To overcome the challenges, we develop a nanoplatform from the supramolecular assembly of β-cyclodextrin grafted hyaluronic acid (HA) and phenylalanine based pseudo protein. The pseudo protein in the nanocomplex provided the hydrophobic interaction and loading capacity for GA, while the HA component targeted the overexpressed CD44 receptor and improved the selective endocytosis in multidrug resistant melanoma cells. The supramolecular nanocomplex provide a promising platform for the delivery of hydrophobic chemotherapeutics to improve the bioavailability and efficiency.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Stimuli-sensitive hollow spheres from chitosan-graft-β-cyclodextrin for controlled drug release

In this paper, sensitive polymeric hollow spheres self-assembled from chitosan-grafted-β-cyclodextrin (CS-g-CD) and sodium tripolyphosphate (TPP) were prepared for controlled release of doxorubicin (DOX). The assemblies were formed by electrostatic interactions between positively charged amino group in CS-g-CD and negatively charged phosphate in TPP. The hollow spheres with diameters about 100nm were confirmed by transmission electron microscopy (TEM) and laser particle analyzer. The microspheres with hollow cavity were beneficial to improve the drug loading capacity for DOX with entrapment efficiency above 60%. The cumulative release of DOX from CS-g-CD/TPP hollow microspheres increased with the decrease of pH and the increase of temperature or ionic strength. At 37 °C and pH 5.2, the maximum drug release was above 90% with a continuous release rate. In-vitro cytotoxicity tests indicate that drug loaded hollow spheres exhibited evidently inhibition against cancer cells. These sensitive polymeric hollow spheres are expected to be used in biomedical field as potential carrier.

Soft Supramolecular Nanoparticles by Noncovalent and Host-Guest Interactions

Supramolecular chemistry provides a tool for the formation of highly ordered structures by means of noncovalent interactions. Soft supramolecular nanoparticles are self-assembled nanoassemblies based on small building blocks and stabilized by basic noncovalent interactions, selective host-guest interactions, or a combination of different interaction types. This review provides an overview of the existing approaches for the formation of supramolecular nanoparticles by various types of noncovalent interactions, with a strong focus on host-guest-mediated assemblies. The approaches are ordered based on the nature of the stabilizing supramolecular interaction, while focusing on the aspects that determine the particle structure. Where applicable, the use of these self-assembled nanostructures as vectors in molecular diagnostics and therapeutics is described as well. The stable yet reversible nature of supramolecular interactions and their chemical flexibility offer great prospects for the development of highly engineered nanoparticles which are compatible with the complexity of living systems.

Supramolecular cyclodextrin-based drug nanocarriers

Hosting of polymers, lipids and drug conjugates makes cyclodextrins suitable to prepare biocompatible, targetable and stimuli-responsive supramolecular drug nanocarriers.

Nanoparticles generated by PEG-Chrysin conjugates for efficient anticancer drug delivery

Nanoparticle-based drug delivery systems promise the safety and efficacy of anticancer drugs. Herein, we presented a facile approach to fabricate novel nanoparticles generated by PEG-Chrysin conjugates for the delivery of anticancer drug doxorubicin. Chrysin was immobilized on the terminal group of methoxy poly(ethylene glycol) (mPEG) to form mPEG-Chrysin conjugate. The conjugates were self-assembled into nanoparticles. Doxorubicin (DOX) was loaded in the nanoparticles. The self-assembly, drug release profiles, interactions between nanoparticle and drug, cellular uptake and in vitro anticancer activity of the DOX loaded nanoparticles were investigated. The results showed that the mean diameters of drug loaded nanoparticles were below 200 nm. Strong π-π stacking interaction was tested within the drug loaded nanoparticles. The drug release rate was closely related to the chain length of PEG, shorter PEG chain resulted faster release. The mPEG-Chrysin conjugate was non-toxic to both 3T3 fibroblasts and HepG2 cancer cells. The cellular uptake measurements demonstrated that the mPEG1000-Chrysin nanoparticles exhibited higher capability in endocytosis. The IC50 of drug loaded mPEG1000-Chrysin nanoparticles was 4.4 μg/mL, which was much lower than that of drug loaded mPEG2000-Chrysin nanoparticles (6.8 μg/mL). These nanoparticles provided a new strategy for fabricating antitumor drug delivery systems.

Facile synthesis of well-defined cyclodextrin-pendant polymer via ATRP for nanostructure fabrication

PEG-b-PCD block copolymer could be synthesized by ATRP of a new methacrylate–CD monomer, and self-assembled into advanced nanostructures with various guest molecules.

Noncovalent interaction-assisted polymeric micelles for controlled drug delivery

Various individual or synergistic noncovalent interactions were employed to mediate polymeric micelles for controlled drug delivery.

Cyclodextrin-based supramolecular systems for drug delivery: recent progress and future perspective

The excellent biocompatibility and unique inclusion capability as well as powerful functionalization capacity of cyclodextrins and their derivatives make them especially attractive for engineering novel functional materials for biomedical applications. There has been increasing interest recently to fabricate supramolecular systems for drug and gene delivery based on cyclodextrin materials. This review focuses on state of the art and recent advances in the construction of cyclodextrin-based assemblies and their applications for controlled drug delivery. First, we introduce cyclodextrin materials utilized for self-assembly. The fabrication technologies of supramolecular systems including nanoplatforms and hydrogels as well as their applications in nanomedicine and pharmaceutical sciences are then highlighted. At the end, the future directions of this field are discussed.

Controlled drug release system based on cyclodextrin-conjugated poly(lactic acid)-b-poly(ethylene glycol) micelles

Cyclodextrin-conjugated poly(lactic acid)-b-poly(ethylene glycol) (β-CD-PLA-mPEG), a well-defined amphiphilic copolymer, was synthesized by controlled ring-open copolymerization and click coupling reaction, in order to obtain a biocompatible drug delivery system with controlled release profiles. The β-CD-PLA-mPEG copolymer could self-assemble in aqueous solution to form micelles with a mean particle size of 173.4 nm, which will decrease to 159.2 nm after loaded with a kind of hydrophobic drug (indomethacin, IND). The IND-loaded β-CD-PLA-mPEG micelles show spherical shape within the nano-size scale under TEM imaging. Compared with that formed by PLA-mPEG, the micelles formed by β-CD-PLA-mPEG copolymer present higher drug loading efficiency and controlled release profile of IND, especially in the control of its initial burst release. Meanwhile, β-CD-PLA-mPEG copolymer exhibits low toxicity to cells. The micelles formed by β-CD-PLA-mPEG copolymer could be a promising controlled release system for various hydrophobic drugs.

Synthesis of β-cyclodextrin containing copolymer via "click" chemistry and its self-assembly in the presence of guest compounds

We report the synthesis of a hydrophilic copolymer with one polyethylene glycol (PEG) block and one β-cyclodextrin (β-CD) containing block by a "click" reaction between azido-substituted β-CD and propargyl flanking copolymer. (1)H NMR study suggested a highly efficient conjugation of β-CD units by this approach. The obtained copolymer was used as a host macromolecule to construct assemblies in the presence of hydrophobic guests. For assemblies containing a hydrophobic polymer, their size can be simply adjusted by simply changing the content of hydrophobic component. By serving as a guest molecule, hydrophobic drugs can also be loaded accompanying the formation of nanoparticles, and the drug payload is releasable. Therefore, the copolymer synthesized herein can be employed as a carrier for drug delivery.