Cyclodextrin-Based Polymeric Materials Bound to Corona Protein for Theranostic Applications

Cyclodextrins (CDs) are cyclic oligosaccharide structures that could be used for theranostic applications in personalized medicine. These compounds have been widely utilized not only for enhancing drug solubility, stability, and bioavailability but also for controlled and targeted delivery of small molecules. These compounds can be complexed with various biomolecules, such as peptides or proteins, via host-guest interactions. CDs are amphiphilic compounds with water-hating holes and water-absorbing surfaces. Architectures of CDs allow the drawing and preparation of CD-based polymers (CDbPs) with optimal pharmacokinetic and pharmacodynamic properties. These polymers can be cloaked with protein corona consisting of adsorbed plasma or extracellular proteins to improve nanoparticle biodistribution and half-life. Besides, CDs have become famous in applications ranging from biomedicine to environmental sciences. In this review, we emphasize ongoing research in biomedical fields using CD-based centered, pendant, and terminated polymers and their interactions with protein corona for theranostic applications. Overall, a perusal of information concerning this novel approach in biomedicine will help to implement this methodology based on host-guest interaction to improve therapeutic and diagnostic strategies.

Biodegradable Polyester of Poly (Ethylene glycol)-sebacic Acid as a Backbone for β -Cyclodextrin-polyrotaxane: A Promising Gene Silencing Vector

BACKGROUND

Polyrotaxane, a macromolecular interlocked assembly, consisting of cyclodextrin has excellent inclusion capabilities and functionalization capacity, which makes it a versatile material as a vector for gene delivery applications.

OBJECTIVE

A biodegradable linear aliphatic polyester axle composed of Polyethylene Glycol (PEG) and Sebacic Acid (SA) was used to fabricate the β-Cyclodextrin (β-CD) based polyrotaxane as a cationic polymeric vector and evaluated for its potential gene silencing efficiency.

METHODS

The water-soluble aliphatic polyester was synthesized by the solvent esterification process and characterized using viscometry, GPC, FT-IR and 1H NMR spectroscopy. The synthesized polyester was further evaluated for its biodegradability and cellular cytotoxicity. Hence, this water-soluble polyester was used for the step-wise synthesis of polyrotaxane, via threading and blocking reactions. Threading of β-CD over PEG-SA polyester axle was conducted in water, followed by end-capping of polypseudorotaxane using 2,4,6-trinitrobenzenesulfonic acid to yield polyester-based polyrotaxane. For gene delivery application, cationic polyrotaxane (PRTx⁺) was synthesized and evaluated for its gene loading and gene silencing efficiency.

RESULTS AND DISCUSSION

The resulting novel macromolecular assembly was found to be safe for use in biomedical applications. Further, characterization by GPC and ¹H NMR techniques revealed successful formation of PE-β-CD-PRTx with a threading efficiency of 16%. Additionally, the cellular cytotoxicity assay indicated biosafety of the synthesized polyrotaxane, exploring its potential for gene delivery and other biomedical applications. Further, the biological profile of PRTx⁺: siRNA complexes was evaluated by measuring their zeta potential and gene silencing efficiency, which were found to be comparable to Lipofectamine 3000, the commercial transfecting agent.

CONCLUSION

The combinatory effect of various factors such as biodegradability, favourable complexation ability, near zero zeta potentials, good cytotoxicity properties of poly (ethylene glycol)-sebacic acid based β-Cyclodextrin-polyrotaxane makes it a promising gene delivery vector for therapeutic applications.

Specific Modification with TPGS and Drug Loading of Cyclodextrin Polyrotaxanes and the Enhanced Antitumor Activity Study in Vitro and in Vivo

A kind of specific cyclodextrin polyrotaxanes (PRs) drug delivery system was developed for an effective drug delivery and enhancing antitumor effect. In this work, we prepared the PR by using α-CD derivatives and dicarboxyl-PEG (M_n = 4200) self-assembling and end-capping with β-CD derivatives. Then, we chose d-a-Tocopheryl polyethylene glycol 1000 succinate (TPGS) with an antitumor effect to modify the PR. The modified PRs have a certain anticancer effect and can assist the anticancer drug to treat cancer. The 10-hydroxycamptothecin (HCPT) was combined to the specific PRs by covalent bonds to prepare drug-loaded specificity PRs (PR-TPGS-HCPT). The enhanced antitumor activities of PR-TPGS-HCPT were studied by in vitro and in vivo experiments, and the experiment results proved that the TPGS could effectively assist the drug to treat cancer and prolong the lifetime of the tumor-bearing mice. Therefore, this research provides a promising drug-loaded material for the cancer treatment and the specific water-soluble PRs will have potential applications in the biomedical field.

Synthesis of the Anionic Hydroxypropyl-β-cyclodextrin:Poly(decamethylenephosphate) Polyrotaxane and Evaluation of its Cholesterol Efflux Potential in Niemann-Pick C1 Cells

Niemann-Pick type C disease (NPC) is a lysosomal storage disease that is characterized by a progressive accumulation of unesterified cholesterol in the lysosomes leading to organ damage from cell dysfunction. Hydroxypropyl-β-cyclodextrin (HP-β-CD) is an attractive drug candidate for treating NPC, as it diminishes cholesterol accumulation in NPC cells. Systemic HP-β-CD treatment, however, is limited by rapid renal clearance. We designed a new anionic HP-β-CD polyrotaxane to act as a slow release formulation based on a polyalkylene phosphate core to improve the pharmacokinetics. The polyalkylene phosphate comprises hydrophobic decamethylene spacers linked by biodegradable anionic phosphodiester bonds. HP-β-CD was threaded onto this polymer first and α-CD afterwards to prevent burst release of the threaded HP-β-CD. Our findings show that HP-β-CD was slowly released from the watersoluble polyrotaxane over a 30 days period. The polyrotaxane provided persistently diminished cholesterol levels in NPC1 cells by 20% relative to untreated cells. These results demonstrate the therapeutic potential of this novel HP-β-CD polyrotaxane for the mobilization of aberrantly stored cholesterol in NPC1 cells.

Bioreducible Poly(Amino Ethers) Based mTOR siRNA Delivery for Lung Cancer

PURPOSE

Lung cancer is one of the leading causes of deaths in the United States, but currently available therapies for lung cancer are associated with reduced efficacy and adverse side effects. Small interfering RNA (siRNA) can knock down the expression of specific genes and result in therapeutic efficacy in lung cancer. Recently, mTOR siRNA has been shown to induce apoptosis in NSCLC cell lines but its use is limited due to poor stability in biological conditions.

METHODS

In this study, we modified an aminoglyocisde-derived cationic poly (amino-ether) by introducing a thiol group using Traut's reagent to generate a bio-reducible modified-poly (amino-ether) (mPAE). The mPAE polymer was used to encapsulate mTOR siRNA by nanoprecipitation method, resulting in the formation of stable and bio-reducible nanoparticles (NPs) which possessed an average diameter of 114 nm and a surface charge of approximately +27 mV.

RESULTS

The mTOR siRNA showed increased release from the mTS-mPAE NPs in the presence of 10 mM glutathione (GSH). The polymeric mTS-mPAE-NPs were also capable of efficient gene knockdown (60 and 64%) in A549 and H460 lung cancer cells, respectively without significant cytotoxicity at 30 μg/ml concentrations. The NPs also showed time-dependent cellular uptake for up to 24 h as determined using flow cytometry. Delivery of the siRNA using these NPs also resulted in significant inhibition of A549 and H460 cell proliferation in vitro, respectively.

CONCLUSIONS

The results demonstrate that the mPAE polymer based NPs show strong potential for siRNA delivery to lung cancer cells. It is anticipated that future modification can help improve the efficacy of nucleic acid delivery, leading to higher inhibition of lung cancer growth in vitro and in vivo.

Polysaccharide-Based Controlled Release Systems for Therapeutics Delivery and Tissue Engineering: From Bench to Bedside

Polysaccharides or polymeric carbohydrate molecules are long chains of monosaccharides that are linked by glycosidic bonds. The naturally based structural materials are widely applied in biomedical applications. This article covers four different types of polysaccharides (i.e., alginate, chitosan, hyaluronic acid, and dextran) and emphasizes their chemical modification, preparation approaches, preclinical studies, and clinical translations. Different cargo fabrication techniques are also presented in the third section. Recent progresses in preclinical applications are then discussed, including tissue engineering and treatment of diseases in both therapeutic and monitoring aspects. Finally, clinical translational studies with ongoing clinical trials are summarized and reviewed. The promise of new development in nanotechnology and polysaccharide chemistry helps clinical translation of polysaccharide-based drug delivery systems.

Highly Functionalized β-Cyclodextrins by Solid-Supported Synthesis

Using covalent capture, a high yielding selective mono-functionalization of heptakis-[6-deoxy-6-(2-aminoethylsulfanyl)]-β-CD with a 5-mercaptopentyl functional group has been achieved. Here, we demonstrate the immobilization of the mono-thiol functionalized β-CD on PEGA resin via a disulfide bond, enabling solid-phase elaboration of the remaining six primary amines. To showcase the potential of this method, the amines were elaborated to tripeptides through standard Fmoc-peptide chemistry. A small library of CD-tripeptide conjugates was generated which, when reduced from the solid support, could be tagged at the released thiol with an environmentally sensitive fluorophore. The resulting library of sensors showed potential for the differential sensing of various bile salts. The described methodology provides a rapid and versatile route to synthesize highly functionalized libraries of CD derivatives that may be tailored towards applications in sensing, catalysis, and multivalent displays.

Lyophilisation and concentration of chitosan/siRNA polyplexes: Influence of buffer composition, oligonucleotide sequence, and hyaluronic acid coating

Chitosan (CS)/siRNA polyplexes have great therapeutic potential for treating multiple diseases by gene silencing. However, clinical application of this technology requires the development of concentrated, hemocompatible, pH neutral formulations for safe and efficient administration. In this study we evaluate physicochemical properties of chitosan polyplexes in various buffers at increasing ionic strengths, to identify conditions for freeze-drying and rehydration at higher doses of uncoated or hyaluronic acid (HA)-coated polyplexes while maintaining physiological compatibility. Optimized formulations are used to evaluate the impact of the siRNA/oligonucleotide sequence on polyplex physicochemical properties, and to measure their in vitro silencing efficiency, cytotoxicity, and hemocompatibility. Specific oligonucleotide sequences influence polyplex physical properties at low N:P ratios, as well as their stability during freeze-drying. Nanoparticles display greater stability for oligodeoxynucleotides ODN vs siRNA; AT-rich vs GC-rich; and overhangs vs blunt ends. Using this knowledge, various CS/siRNA polyplexes are prepared with and without HA coating, freeze-dried and rehydrated at increased concentrations using reduced rehydration volumes. These polyplexes are non-cytotoxic and preserve silencing activity even after rehydration to 20-fold their initial concentration, while HA-coated polyplexes at pH∼7 also displayed increased hemocompatibility. These concentrated formulations represent a critical step towards clinical development of chitosan-based oligonucleotide intravenous delivery systems.

One-pot synthesis of water-soluble, β-cyclodextrin-based polyrotaxanes in a homogeneous water system and its use in bio-applications

A small, nano-sized, water-soluble polyrotaxane (PR) was synthesized using a highly efficient one-pot synthesis strategy in a homogeneous water system, formed from β-cyclodextrin-(COOH)₂, poly(propylene glycol)bis(2-aminopropyl ether) (PPG, 2 kDa) and a mono-(6-azido-6-desoxy)-β-cyclodextrin stopper via room temperature click chemistry. β-cyclodextrin-(COOH)₂ and PR were characterized by one- and two-dimensional NMR as well as by high resolution transmission electron microscopy (HR-TEM). The number of carboxyl groups in one PR was determined by ¹H NMR. Two-dimensional diffusion-ordered NMR spectroscopy (2D DOSY) and nuclear Overhauser enhancement spectroscopy (2D NOESY) show that β-cyclodextrin-(COOH)₂ and PPG successfully formed an inclusion complex. HR-TEM revealed the morphology of water-soluble PR as a spherical nanoparticle with a size of approximately 3.5 nm ± 1.5 nm. PR was labeled with rhodamine to assess its biocompatibility and cell membrane penetrability in vitro. The in vivo real-time fluorescent imaging biodistribution experiments indicated that water-soluble PR can actively target tumor sites using an enhanced permeability and retention (EPR) effect, with a significantly prolonged blood circulation time in tumor-bearing mice.