Novel Functional Hyperbranched Polyether Polyols as Prospective Drug Delivery Systems

A new mode of Thinfilm and Nanofiber for burst release of the drug for Alzheimer disease; A complete scenario from dispersible polymer to formulation methodology

Alzheimer's disease (AD) is usually caused intellectual deterioration which happened due to the degeneration of cholinergic neurons. Donepezil is employed for cholinesterase enzyme Inhibition (ChEI) to treat AD in a wider population. Over the years, researchers finding difficulties prompted through traditional dosage forms particularly in geriatric patience. To avoid swallowing difficulties brought about with the aid of the AD population, researchers majorly focused on oral thin-film technology (OTF). This technology strongly eliminates issues caused by solid oral dosage forms. It is one of the quality strategies to an alternate drug that is used in the first-pass metabolism or pre systematic metabolism. The solubility of the drug is a higher trouble and it can expand by way of lowering particle size. Nanofibers are the excellent desire to minimize the drug particles to the submicron stage and can increase the drug release rate drastically. It can be prepared by Electrospinning technology by incorporating polymeric material into poorly soluble drugs. Mostly natural and biodegradable polymers prefer in all pharmaceutical preparations. Polymers employed for oral delivery should be stable, possess mucoadhesive property, and should release the drug by diffusion, degradation, and swelling mechanism. The objective of the present review explains various thin-film and nanofiber formulations used for faster drug release in the treatment of Alzheimer's disease.

Targeted Drug Delivery: Trends and Perspectives

BACKGROUND

Due to various limitations in conventional drug delivery system, it is important to focus on the target-specific drug delivery system where we can deliver the drug without any degradation. Among various challenges faced by a formulation scientist, delivering the drug to its right site, in its right dose, is also an important aim. A focused drug transport aims to extend, localize, target and have a safe drug interaction with the diseased tissue.

OBJECTIVE

The aim of targeted drug delivery is to make the required amount of the drug available at its desired site of action. Drug targeting can be accomplished in a number ways that include enzyme mediation, pH-dependent release, use of special vehicles, receptor targeting among other mechanisms. Intelligently designed targeted drug delivery systems also offer the advantages of a low dose of the drug along with reduced side effects which ultimately improves patient compliance. Incidences of dose dumping and dosage form failure are negligible. A focused drug transport aims to have a safe drug interaction with the diseased tissue.

CONCLUSION

This review focuses on the available targeting techniques for delivery to the colon, brain and other sites of interest. Overall, the article should make an excellent read for the researchers in this area. Newer drug targets may be identified and exploited for successful drug targeting.

Dendrimer Architectonics to Treat Cancer and Neurodegenerative Diseases with Implications in Theranostics and Personalized Medicine

Integration of diagnostic and therapeutic functions in a single platform namely theranostics has become a cornerstone for personalized medicine. Theranostics platform facilitates noninvasive detection and treatment while allowing the monitoring of disease progression and therapeutic efficacy in case of chronic conditions of cancer and Alzheimer's disease (AD). Theranostic tools function by themselves or with the aid of carrier, viz. liposomes, micelles, polymers, or dendrimers. The dendrimer architectures (DA) are well-characterized molecular nanoobjects with a large number of terminal functional groups to enhance solubility and offer multivalency and multifunctional properties. Various noninvasive diagnostic tools like magnetic resonance imaging (MRI), computed tomography (CT), gamma scintigraphy, and optical techniques have been accomplished utilizing DAs for simultaneous imaging and drug delivery. Obstacles in the formulation design, drug loading, payload delivery, biocompatibility, overcoming cellular membrane and blood-brain barrier (BBB), and systemic circulation remain a bottleneck in translational efforts. This review focuses on the diagnostic, therapeutic and theranostic potential of DA-based nanocarriers in treating cancer and neurodegenerative disorders like AD and Parkinson's disease (PD), among others. In view of the inverse relationship between cancer and AD, designing suitable DA-based theranostic nanodrug with high selectivity has tremendous implications in personalized medicine to treat cancer and neurodegenerative disorders.

Defects and defect engineering in Soft Matter

Soft matter covers a wide range of materials based on linear or branched polymers, gels and rubbers, amphiphilic (macro)molecules, colloids, and self-assembled structures. These materials have applications in various industries, all highly important for our daily life, and they control all biological functions; therefore, controlling and tailoring their properties is crucial. One way to approach this target is defect engineering, which aims to control defects in the material's structure, and/or to purposely add defects into it to trigger specific functions. While this approach has been a striking success story in crystalline inorganic hard matter, both for mechanical and electronic properties, and has also been applied to organic hard materials, defect engineering is rarely used in soft matter design. In this review, we present a survey on investigations on defects and/or defect engineering in nine classes of soft matter composed of liquid crystals, colloids, linear polymers with moderate degree of branching, hyperbranched polymers and dendrimers, conjugated polymers, polymeric networks, self-assembled amphiphiles and proteins, block copolymers and supramolecular polymers. This overview proposes a promising role of this approach for tuning the properties of soft matter.

Encapsulation property of hyperbranched polyglycerols as prospective drug delivery systems

Hyperbranched polyglycerols (hbPGs) were investigated as nanocarriers to encapsulate and deliver guest molecules.

Molecular dynamics simulation studies of hyperbranched polyglycerols and their encapsulation behaviors of small drug molecules

Computer simulation could disclose more details about the conformations of HPGs and their encapsulation behaviors of guest molecules.

Inhibition of fibrous dysplasia via blocking Gsα with suramin sodium loaded with an alendronate-conjugated polymeric drug delivery system

A bone-targeted polymeric drug delivery system was constructed to inhibit fibrous dysplasia efficiently via blocking Gsα with suramin sodium.

Bioapplications of hyperbranched polymers

The recent research progress in biological and biomedical applications of hyperbranched polymers has been summarized in this review.

Hyperbranched polymers: advances from synthesis to applications

This review summarizes the advances in hyperbranched polymers from the viewpoint of structure, click synthesis and functionalization towards their applications in the last decade.

Synthesis and therapeutic applications of biocompatible or biodegradable hyperbranched polymers

The recent progress in the synthesis, modifications and therapeutic applications of biocompatible or biodegradable hyperbranched polymers has been reviewed.

A bifunctional nanocarrier based on amphiphilic hyperbranched polyglycerol derivatives

We here report on the synthesis of a bifunctional nanocarrier system based on amphiphilic hyperbranched polyglycerol (hPG), which is modified by introducing hydrophobic aromatic groups to the core and retaining hydrophilic groups in the shell. "Selective chemical differentiation" and chemo-enzymatic reaction strategies were used to synthesize this new core-shell type nanocarrier. The system shows an innovative bifunctional carrier capacity with both polymeric and unimolecular micelle-like transport properties. Hydrophobic guest molecules such as pyrene were encapsulated into the hydrophobic core of modified hPG via hydrophobic interactions as well as π-π stacking, analogous to a unimolecular micelle system. A second guest molecule, which has a high affinity to the shell like nile red, was solubilized in the outer shell of the host molecule, thus connecting the nanocarrier molecules to form aggregates. This model is confirmed by UV-Vis, fluorescence, atomic force microscopy, and dynamic light scattering, as well as release studies triggered by pH-changes and enzymes. Encapsulated guest molecules, respectively in the core and in the shell, present different controlled release profiles. The bifunctional nanocarrier system is a promising candidate for simultaneous delivery of different hydrophobic drugs for a combination therapy, e.g., in tumor treatment.

Dendrimer nanoscaffolds for potential theranostics of prostate cancer with a focus on radiochemistry

Dendrimers are a class of structurally defined macromolecules featured with a central core, a low-density interior formed by repetitive branching units, and a high-density exterior terminated with surface functional groups. In contrast to their polymeric counterparts, dendrimers are nanosized and symmetrically shaped, which can be reproducibly synthesized on a large scale with monodispersity. These unique features have made dendrimers of increasing interest for drug delivery and other biomedical applications as nanoscaffold systems. Intended to address the potential use of dendrimers for the development of theranostic agents, which combines therapeutics and diagnostics in a single entity for personalized medicine, this review focuses on the reported methodologies of using dendrimer nanoscaffolds for targeted imaging and therapy of prostate cancer. Of particular interest, relevant chemistry strategies are discussed due to their important roles in the design and synthesis of diagnostic and therapeutic dendrimer-based nanoconjugates and potential theranostic agents, targeted or nontargeted. Given the developing status of nanoscaffolded theranostics, major challenges and potential hurdles are discussed along with the examples representing current advances.

Poly (ethylene glycol)-armed hyperbranched polyoxetanes for anticancer drug delivery

A facile method for synthesis of polyethylene glycol (PEG)-armed hyperbranched polyoxetanes is presented as well as characterization and use in drug delivery. A series of hyperbranched polyoxetanes with multiple PEG arms were synthesized via a one-pot cationic ring-opening polymerization of 3-ethyl-3-hydroxymethyloxetane (EHMO) and its PEGylated derivative (EPMO), in which the feed mass ratio of EHMO to EPMO was 98:2, 96:4, 74:26, or 17:83. Characterization methods included NMR, DLS, FT-IR, DSC, and SEM. Toxicity of the synthesized polymers to human dermal fibroblasts was evaluated using the MTT assay. Formulation into particles was carried out to encapsulate the anticancer drug camptothecin using the single oil-in-water (o/w) solvent evaporation method. The resulting drug encapsulated particles were evaluated for antitumor activity using HN12 cells.

Synthesis of biodegradable amphiphilic nanocarriers by chemo-enzymatic transformations for the solubilization of hydrophobic compounds

Polymeric nanocarriers possess advanced physicochemical properties that improve bioavailability, enhance cellular dynamics, and control target ability in drug delivery. In particular, dendritic polyglycerol is a promising new biocompatible scaffold for drug delivery. The present study explores the chemo-enzymatic modifications on dendritic hyperbranched polyglycerol (dPG) leading to amphiphilic polymeric architectures with easily hydrolysable ester linkages. Furthermore, these architectures were studied for nile red solubilization with capacity up to 5.6 mg/L at 0.1 wt % polymer conc. This corresponds to an ~10 fold increase in solubility of nile red. The release of nile red from these polymers was observed with a half life of 8 hours at pH 5.0, while no release was found at pH 7.4. The cell viability studies of our polymeric architectures showed them to be relatively nontoxic and to have the potential for future drug delivery applications.

Bioreducible micelles self-assembled from amphiphilic hyperbranched multiarm copolymer for glutathione-mediated intracellular drug delivery

A new type of biodegradable micelles for glutathione-mediated intracellular drug delivery was developed on the basis of an amphiphilic hyperbranched multiarm copolymer (H40-star-PLA-SS-PEP) with disulfide linkages between the hydrophobic polyester core and hydrophilic polyphosphate arms. The resulting copolymers were characterized by nuclear magnetic resonance (NMR), Fourier transformed infrared (FTIR), gel permeation chromatography (GPC), and differential scanning calorimeter (DSC) techniques. Benefiting from amphiphilic structure, H40-star-PLA-SS-PEP was able to self-assemble into micelles in aqueous solution with an average diameter of 70 nm. Moreover, the hydrophilic polyphosphate shell of these micelles could be detached under reduction-stimulus by in vitro evaluation, which resulted in a rapid drug release due to the destruction of micelle structure. The glutathione-mediated intracellular drug delivery was investigated against a Hela human cervical carcinoma cell line. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements demonstrated that H40-star-PLA-SS-PEP micelles exhibited a faster drug release in glutathione monoester (GSH-OEt) pretreated Hela cells than that in the nonpretreated cells. Cytotoxicity assay of the doxorubicin-loaded (DOX-loaded) micelles indicated the higher cellular proliferation inhibition against 10 mM of GSH-OEt pretreated Hela cells than that of the nonpretreated ones. As expected, the DOX-loaded micelles showed lower inhibition against 0.1 mM of buthionine sulfoximine (BSO) pretreated Hela cells. These reduction-responsive and biodegradable micelles show a potential to improve the antitumor efficacy of hydrophobic chemotherapeutic drugs.

Synthesis and characterization of carboxylic acid conjugated, hydrophobically derivatized, hyperbranched polyglycerols as nanoparticulate drug carriers for cisplatin

Hyperbranched polyglycerols (HPGs) with hydrophobic cores and derivatized with methoxy poly(ethylene glycol) were synthesized and further functionalized with carboxylate groups to bind and deliver cisplatin. Low and high levels of carboxylate were conjugated to HPGs (HPG-C(8/10)-MePEG(6.5)-COOH(113) and HPG-C(8/10)-MePEG(6.5)-COOH(348)) and their structures were confirmed through NMR and FTIR spectroscopy and potentiometric titration. The hydrodynamic diameter of the HPGs ranged from 5-10 nm and the addition of COOH groups decreased the zeta potential of the polymers. HPG-C(8/10)-MePEG(6.5)-COOH(113) bound up to 10% w/w cisplatin, whereas HPG-C(8/10)-MePEG(6.5)-COOH(348) bound up to 20% w/w drug with 100% efficiency. Drug was released from HPG-C(8/10)-MePEG(6.5)-COOH(113) over 7 days at the same rate, regardless of the pH. Cisplatin release from HPG-C(8/10)-MePEG(6.5)-COOH(348) was significantly slower than HPG-C(8/10)-MePEG(6.5)-COOH(113) at pH 6 and 7.4, but similar at pH 4.5. Release of cisplatin into artificial urine was considerably faster than into buffer. Carboxylated HPGs demonstrated good biocompatibility, and drug-loaded HPGs effectively inhibited proliferation of KU-7-luc bladder cancer cells.

Development and in vitro characterization of paclitaxel and docetaxel loaded into hydrophobically derivatized hyperbranched polyglycerols

In this study we report the development and in vitro characterization of paclitaxel (PTX) and docetaxel (DTX) loaded into hydrophobically derivatized hyperbranched polyglycerols (HPGs). Several HPGs derivatized with hydrophobic groups (C(8/10) alkyl chains) (HPG-C(8/10)-OH) and/or methoxy polyethylene glycol (MePEG) chains (HPG-C(8/10)-MePEG) were synthesized. PTX or DTX were loaded into these polymers by a solvent evaporation method and the resulting nanoparticle formulations were characterized in terms of size, drug loading, stability, release profiles, cytotoxicity, and cellular uptake. PTX and DTX were found to be chemically unstable in unpurified HPGs and large fractions (∼80%) of the drugs were degraded during the preparation of the formulations. However, both PTX and DTX were found to be chemically stable in purified HPGs. HPGs possessed hydrodynamic radii of less than 10nm and incorporation of PTX or DTX did not affect their size. The release profiles for both PTX and DTX from HPG-C(8/10)-MePEG nanoparticles were characterized by a continuous controlled release with little or no burst phase of release. In vitro cytotoxicity evaluations of PTX and DTX formulations demonstrated a concentration-dependent inhibition of proliferation in KU7 cell line. Cellular uptake studies of rhodamine-labeled HPG (HPG-C(8/10)-MePEG(13)-TMRCA) showed that these nanoparticles were rapidly taken up into cells, and reside in the cytoplasm without entering the nuclear compartment and were highly biocompatible with the KU7 cells.

Self-assembly of hyperbranched polymers and its biomedical applications

Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano-technology and functional materials.

Self-assembled micelles from an amphiphilic hyperbranched copolymer with polyphosphate arms for drug delivery

A novel type of amphiphilic hyperbranched multiarm copolymer [H40-star-(PLA-b-PEP-OH)] was synthesized through a two-step ring-opening polymerization (ROP) procedure and applied to drug delivery. First, Boltorn H40 was used as macroinitiator for the ROP of L-lactide to form the intermediate (H40-star-PLA-OH). Then, the ROP of ethyl ethylene phosphate was further initiated to produce H40-star-(PLA-b-PEP-OH). The resulting hyperbranched multiarm copolymers were characterized by (1)H, (13)C, and (31)P NMR, GPC, and FTIR spectra. Benefiting from the amphiphilic structure, H40-star-(PLA-b-PEP-OH) was able to self-assemble into micelles in water with an average diameter of 130 nm. In vitro evaluation of these micelles demonstrated their excellent biocompatibility and efficient cellular uptake by methyl tetrazolium assay, flow cytometry, and confocal laser scanning microscopy measurements. Doxorubicin-loaded micelles were investigated for the proliferation inhibition of a Hela human cervical carcinoma cell line, and the Doxorubicin dose required for 50% cellular growth inhibition was found to be 1 microg/mL. These results indicate that H40-star-(PLA-b-PEP-OH) micelles can be used as safe, promising drug-delivery systems.

Hyperbranched polyamidoamines containing beta-cyclodextrin for controlled release of chlorambucil

This work is focused on the controlled drug release behavior of hyperbranched HPMA in the presence of beta-CD. Hence, three HPMA-beta-CDs and a pure HPMA were synthesized by Michael addition polymerization. As a model drug, CLB (an anti-cancer drug) was loaded into them via a solution method for in vitro release studies. The DSC results indicate that the CLB/polymer interactions are at the molecular level. Loading CLB into these polymers results in an evident increase in their glass transition temperatures, and DeltaT(g) depends on the beta-CD content. The controlled-release experiments show that the presence of beta-CD can appropriately slow the release of CLB from HPMA-beta-CDs and adjust the ratio of CLB released in total drug loading.

Dendritic polyglycerols for biomedical applications

The application of nanotechnology in medicine and pharmaceuticals is a rapidly advancing field that is quickly gaining acceptance and recognition as an independent area of research called "nanomedicine". Urgent needs in this field, however, are biocompatible and bioactive materials for antifouling surfaces and nanoparticles for drug delivery. Therefore, extensive attention has been given to the design and development of new macromolecular structures. Among the various polymeric architectures, dendritic ("treelike") polymers have experienced an exponential development due to their highly branched, multifunctional, and well-defined structures. This Review describes the diverse syntheses and biomedical applications of dendritic polyglycerols (PGs). These polymers exhibit good chemical stability and inertness under biological conditions and are highly biocompatible. Oligoglycerols and their fatty acid esters are FDA-approved and are already being used in a variety of consumer applications, e.g., cosmetics and toiletries, food industries, cleaning and softening agents, pharmaceuticals, polymers and polymer additives, printing photographing materials, and electronics. Herein, we present the current status of dendritic PGs as functional dendritic architectures with particular focus on their application in nanomedicine, in drug, dye, and gene delivery, as well as in regenerative medicine in the form of non-fouling surfaces and matrix materials.