A novel reactive oxygen species (ROS)-responsive nanoplatform can be successfully manufactured from a ROS-triggerable ?-cyclodextrin material. Extensive in vitro and in vivo studies validate that this nanoscaled system may serve as a new drug delivery vehicle with well-defined ROS-sensitivity and superior biocompatibility. This nanocarrier can be used for ROS-triggered transport of diverse therapeutics and imaging agents.
The deficient osseointegration and implant-associated infections are pivotal issues for the long-term clinical success of endosteal Ti implants, while development of functional surfaces that can simultaneously overcome these problems remains highly challenging. This study aimed to fabricate sophisticated Ti implant surface with both osteogenic inducing activity and inherent antibacterial ability simply via tailoring surface topographical features. Micro/submciro/nano-scale structure was constructed on Ti by three cumulative subtractive methods, including sequentially conducted sandblasting as well as primary and secondary acid etching treatment. Topographical features of this hierarchical structure can be well tuned by the time of the secondary acid treatment. Ti substrate with mere micro/submicro-scale structure (MS0-Ti) served as a control to examine the influence of hierarchical structures on surface properties and biological activities. Surface analysis indicated that all hierarchically structured surfaces possessed exactly the same surface chemistry as that of MS0-Ti, and all of them showed super-amphiphilicity, high surface free energy, and high protein adsorption capability. Biological evaluations revealed surprisingly antibacterial ability and excellent osteogenic activity for samples with optimized hierarchical structure (MS30-Ti) when compared with MS0-Ti. Consequently, for the first time, a hierarchically structured Ti surface with topography-induced inherent antibacterial capability and excellent osteogenic activity was constructed.
There is still unmet demand for developing powerful approaches to produce polymeric nanoplatforms with versatile functions and broad applications, which are essential for the successful bench-to-bedside translation of polymeric nanotherapeutics developed in the laboratory. We have discovered a facile, convenient, cost-effective and easily scalable one-pot strategy to assemble various lipophilic therapeutics bearing carboxyl groups into nanomedicines, through which highly effective cargo loading and nanoparticle formation can be achieved simultaneously. Besides dramatically improving water solubility, the assembled nanopharmaceuticals showed significantly higher bioavailability and much better therapeutic activity. These one-pot assemblies may also serve as nanocontainers to effectively accommodate other highly hydrophobic drugs such as paclitaxel (PTX). PTX nanomedicines thus formulated display strikingly enhanced in vitro antitumor activity and can reverse the multidrug resistance of tumor cells to PTX therapy. The special surface chemistry offers these assembled entities the additional capability of efficiently packaging and efficaciously transfecting plasmid DNA, with a transfection efficiency markedly higher than that of commonly used positive controls. Consequently, this one-pot assembly approach provides a facile route to multifunctional nanoplatforms for simultaneous delivery of multiple therapeutics with improved therapeutic significance.
The proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a key pathophysiological component of vascular remodeling in pulmonary arterial hypertension (PAH), an intractable disease, for which pharmacotherapy is limited and only slight improvement in survival outcomes have achieved over the past few decades. RNA interference provides a highly promising strategy to the treatment of this chronic lung disease, while efficient delivery of small interfering RNA (siRNA) remains a key challenge for the development of clinically acceptable siRNA therapeutics. With the aim to construct useful nanomedicines, the mammalian target of rapamycin (mTOR) siRNA was loaded into hybrid nanoparticles based on low molecular weight (Mw) polyethylenimine (PEI) and a pH-responsive cyclodextrin material (Ac-aCD) or poly(lactic-co-glycolic acid) (PLGA). This hybrid nanoplatform gave rise to desirable siRNA loading, and the payload release could be modulated by the hydrolysis characteristics of carrier materials. Fluorescence observation and flow cytometry quantification suggested that both Ac-aCD and PLGA nanovectors (NVs) may enter PASMCs under either normoxia or hypoxia conditions as well as in the presence of serum, with uptake and transfection efficiency significantly higher than those of cationic vectors such as PEI with Mw of 25 kDa (PEI25k) and Lipofectamine 2000 (Lipo 2k). Hybrid Ac-aCD or PLGA NV containing siRNA remarkably inhibited proliferation and activated apoptosis of hypoxic PASMCs, largely resulting from effective suppression of mTOR signaling as evidenced by significantly lowered expression of mTOR mRNA and phosphorylated protein. Moreover, these hybrid nanomedicines were more effective than commonly used cationic vectors like PEI25k and Lipo 2k, with respect to cell growth inhibition, apoptosis activation, and expression attenuation of mTOR mRNA and protein. Therefore, mTOR siRNA nanomedicines based on hybrid Ac-aCD or PLGA NV may be promising therapeutics for diseases related to hypoxic abnormal growth of PASMCs.
To examine the effect of surface chemistry and surface charge on in vivo biodistribution and toxicity of CdSe/ZnS core-shell quantum dots (QDs), QDs with positive, negative, or PEG coating are used in this study for in vivo evaluation in a mouse model. The results suggest that QDs coated with cationic polydiallyldimethylammonium chloride (PDDA) preferentially deposit in the lung other than in the liver, while the negative and PEGylated QDs render abundant accumulation in the liver. At higher doses positive QDs with PDDA coating show severe acute toxicity due to pulmonary embolism. Independent of their surface coatings, all QDs cause injuries in specific tissues like liver, spleen, lung, and kidney, after acute and long-term exposure, and the degree of injuries is dominated by their surface properties. For the positively charged QDs, the acute phase toxicity is primarily contributed by the coating material PDDA, while coating on QDs may amplify both in vitro and in vivo toxicity of PDDA. PEGylated QDs display the slightest chronic injuries in the long-term toxicity examination in comparison to positive or negative ones.
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.
Engineering of pH-responsive nanoplatforms can be facilely achieved from acetalated ?-cyclodextrin materials. The hydrolysis period of nanoparticles can be precisely tailored by using materials with various acetal types that can be easily controlled by acetalation time. These nanomaterials with pH-modulated hydrolysis and pH-triggered drug delivery capability show good biocompatibility in vitro and in vivo. Incorporation of anticancer drug paclitaxel (PTX) into newly developed pH-sensitive nanosystems leads to nanotherapeutics with significantly improved cytotoxic activity against various tumor cells. Importantly, thus formulated nanomedicines can reverse the multidrug resistance of PTX-resistant cancer cells. In vivo antitumor studies also reveal the superior of pH-sensitive nanosystems over pristine PTX and pH-insensitive PLGA nanoformulations. Moreover, comparison with other two acid-labile materials evidenced the advantages of cyclodextrin-based nanovehicles with respect to drug loading capacity, in vitro and in vivo activity as well as alleviated adverse effects. These pH-responsive nanoparticles may serve as new generation nanocarriers for drug delivery.
With the aim to establish new strategies for fabricating bioactive nanostructured matrices for controlled drug delivery or potential tissue engineering, a facile and one-pot protocol was developed in this study to produce drug-loaded poly(l-lactide) (PLLA) nanostructures by thermally induced phase separation. Using both steroidal and nonsteroidal anti-inflammatory drugs, we demonstrated that lipophilic drugs can be efficiently incorporated in either nanosheet-like or nanofibrous PLLA matrices. Thus entrapped drug was randomly distributed in the interconnected nanostructures in the form of nanoscaled crystals. In vitro release study revealed that drug release kinetics may be modulated, on the one hand, by the nanostructure of matrices, while on the other hand by the polymer concentration utilized for fabrication. As for hydrophilic compounds, they could be conveniently loaded into nanofibrous structure by post-fabrication absorption. In addition to the conceptual proof of potential applications of nanostructured PLLA matrices for controlled drug delivery, the strategy employed herein offers a new way to construct bioactive scaffolds, such as antibacterial or anti-inflammatory scaffolds, which may find broad applications for tissue regeneration and stem cells-based biotherapy.
This study aimed at constructing a novel disulfide-crosslinked collagen I/hyaluronic acid polyelectrolyte multilayer (PEM) coating incorporated with bFGF and arginine-glycine-aspartic acid on titanium via the layer-by-layer technique, and evaluating its biological effects.
The absence of safe, efficient, cost-effective, and easily scalable delivery platforms is one of the most significant hurdles and critical issues that limit the bench to bedside translation of oligonucleotides-based therapeutics. Acid-labile materials are of special interest in developing nonviral vectors due to their capability of intracellularly delivering therapeutic payload. In this study, a nanovector was designed by integrating a pH-responsive cyclodextrin material and low molecular weight polyethylenimine (PEI). Antisense oligonucleotide (ASON) Bcl-xl could be encapsulated into this hybrid nanosystem with extremely high loading efficiency by a nanoemulsion technique. The developed pH-responsive ASON nanotherapeutics could be efficiently transfected into human lung adenocarcinoma cells in a time- and dose-dependent manner, resulting in effective cell growth inhibition, significant suppression on the expression of Bcl-xl mRNA/protein, and efficient cell apoptosis. Importantly, the new nanovector showed drastically higher efficacy and lower cytotoxicity when compared with PLGA-based counterpart and commonly used cationic vectors like branched PEI (25,000 Da) and Lipofectamine 2000. This pH-responsive hybrid nanosystem may serve as a safe and efficient nonviral vector that may find wide applications in gene therapy.
Double hydrophilic copolymers (PEG-b-PCDs) with one PEG block and another block containing ?-cyclodextrin (?-CD) units were synthesized by macromolecular substitution reaction. Via a dialysis procedure, complex assemblies with a core-shell structure were prepared using PEG-b-PCDs in the presence of a hydrophobic homopolymer poly(?-benzyl L-aspartate) (PBLA). The hydrophobic PBLA resided preferably in the cores of assemblies, while the extending PEG chains acted as the outer shell. Host-guest interaction between ?-CD and hydrophobic benzyl group was found to mediate the formation of the assemblies, where PEG-b-PCD and PBLA served as the host and guest macromolecules, respectively. The particle size of the assemblies could be modulated by the composition of the host PEG-b-PCD copolymer. The molecular weight of the guest polymer also had a significant effect on the size of the assemblies. The assemblies prepared from the host and guest polymer pair were stable during a long-term storage. These assemblies could also be successfully reconstituted after freeze-drying. The assemblies may therefore be used as novel nanocarriers for the delivery of hydrophobic drugs.
Polystyrene-poly(acrylic acid)/poly(allylamine hydrochloride) polyelectrolyte multilayer was found to be instable and apt to reconstruct in the pure water. By depositing polystyrene-poly(acrylic acid)/poly(allylamine hydrochloride) multilayer on the polystyrene-poly(acrylic acid) hybrid CaCO(3) templates, novel polyelectrolyte capsules could be prepared after the removal of the templates. The resultant capsules could keep their three-dimensional (3D) spherical shape after being dried at room temperature, dramatically different from the conventional polyelectrolyte capsules based on nonhybrid templates by layer-by-layer procedure. The instable polyelectrolyte multilayer, hybrid templates, and assembly cycles were demonstrated to be three indispensable factors responsible for the formation of this type of 3D stable capsules. The formation mechanism was also discussed in this study.
This study presents the construction and evaluation of highly efficient nanomedicines via self-assembly directed by multiple non-covalent interactions between carrier polymer and cargo molecules, including hydrophobic, host-guest recognition, hydrogen bonding and electrostatic forces. ?-Cyclodextrin conjugated polyethyleneimine (PEI-CD) was employed as the model carrier material, while indomethacin (IND), a nonsteroidal anti-inflammatory drug, was used as the drug model. Spontaneous assembly of PEI-CD and IND led to core-shell structured nanoparticles with a positive surface and pH-triggering behavior as well as high drug loading capacity. These nano-assemblies can function as gastro-OFF/intestinal-ON delivery systems to selectively transport payload to enteric sites, thereby dramatically increasing the oral bioavailability of the loaded therapeutic, which can also serve as multifunctional nano-platforms for multiple delivery of various therapeutics. In addition, the strategy employed herein may provide new insights into the design of novel nanocarriers by self-assembling.
Supramolecular nanostructures assembled by polymeric amphiphiles have been intensively studied during the last two decades. Such nanocarriers may be engineered to possess on-demand bio-responsitivity for the prevention, diagnosis, and treatment of human diseases. The successful development of several nanoassembly-based polymer therapeutics further encouraged scientists to develop nano-vehicles to achieve controlled release, enhanced efficacy, improved specificity and reduced toxicity. Different from the abundant existing literatures on the hydrophobically or electrostatically driven self-assemblies and their therapeutic applications, this article reviews host-guest interaction mediated nanoassemblies, especially those constructed using cyclodextrins as the host entities. The excellent biocompatibility, complexation capacity, and chemical-sensitivity of cyclodextrin make cyclodextrin-containing polymers attractive to construct host-guest nanoassemblies. Such nanocarriers may be advantageous also because of the broad availability of cyclodextrins, their flexibility for structure/property modulation and their chemical-responsive characteristics.
We report the construction of novel temperature-responsive assemblies based on a double hydrophilic block copolymer (consisting of a PEG block and a ?-cyclodextrin-containing block, PEG-b-PCD) and poly(N-isopropylacrylamide) (PNIPAm). Thus formed nano-assemblies exhibit a spherical morphology and have a temperature-responsive loose core. The driving force for the formation of these assemblies was found to be the inclusion complexation interaction between the hydrophobic cavity of ?-cyclodextrin and the isopropyl group of PNIPAm. The particle size of these assemblies changed reversibly in response to the external temperature change. The particle size also changed with the PNIPAm/PEG-b-PCD weight ratio. A model hydrophobic drug (indomethacin) was loaded into these assemblies with a high efficiency. An in vitro release study showed that the payload could be released in a sustained manner after an initial burst release. The release rate could be switched between high and low in an ON/OFF fashion by temperature. These results demonstrate that the nano-assemblies have high potential for applications in controlled drug delivery and biomedicine when temperature responsiveness is desired.
Double hydrophilic copolymers with one polyethylene glycol (PEG) block and one beta-cyclodextrin (beta-CD) flanking block (PEG-b-PCDs) were synthesized through the post-modification of macromolecules. The self-assembly of PEG-b-PCDs in aqueous solutions was initially studied by a fluorescence technique. This measurement together with AFM and TEM characterizations demonstrated the formation of nanoparticles in the presence of lipophilic small molecules. The host-guest interaction between the beta-CD unit of a host copolymer and the hydrophobic group of a guest molecule was found to be the driving force for the observed self-assembly. This spontaneous assembly upon loading of guest molecules was also observed for hydrophobic drugs with various chemical structures. Relatively high drug loading was achieved by this approach. Desirable encapsulation was also achieved for the hydrophobic drugs that cannot efficiently interact with free beta-CD. In vitro release studies suggested that the payload in nano-assemblies could be released in a sustained manner. In addition, both the fluorescence measurement and the in vitro drug release studies suggested that these nano-assemblies mediated by the inclusion complexation exhibited a chemical sensitivity. The release of payload can be accelerated upon the triggering by hydrophobic guest molecules or free beta-CD molecules. These results support the potential applications of the synthesized copolymers for the delivery of hydrophobic drugs.
Novel core-shell structured nanoassemblies are assembled by a beta-cyclodextrin containing a positively charged host polymer and a hydrophobic guest polymer. The hydrophobic core of these types of assemblies serves as a nanocontainer to load and release the hydrophobic drugs, while the positively charged hydrophilic shell is able to condense the plasmid DNA and achieve its transfection/expression in osteoblast cells. These assemblies may be used as a new generation of multifunctional nanocarriers for simultaneous drug delivery and gene therapy.
Multi-morphologic polymer nano-assemblies, such as micelles and vesicles, have been intensively studied recently by scientists in the multidisciplinary fields for their promising applications in bioengineering, biomedicine and pharmaceutics. With the success of several micellar formulations in clinical trials, more and more therapeutics based on polymer assemblies are on the pipeline for clinical applications. The current review summarizes some recent patents on the polymer nano-assemblies including micelles and vesicles, with the focus on drug delivery and gene therapy. For the lack of updated patents, the selected progress made most recently in this field has been presented based on the newly published articles. The future development in this active and exciting field has been discussed as well. Because of the huge literature of scientific papers on delivery systems based on polymer assemblies in recent years, this review attempts to limit the specific examples to those that are currently in clinical trials. Accordingly, it is impossible to properly credit all the scientists in this field. The author apologizes in advance for all omissions.
"Micelle-enhanced" polyelectrolyte capsules were fabricated via a layer-by-layer technique, templated on hybrid calcium carbonate particles with built-in polymeric micelles based on polystyrene-b-poly(acrylic acid). Due to the presence of a large number of negatively charged micelles inside the polyelectrolyte capsule, which were liberated from templates, the capsule wall was reconstructed and had properties different to those of conventional polyelectrolyte capsules. This type of capsule could selectively entrap positively charged water-soluble substances. The encapsulation efficiency of positively charged substances was dependent on their molecular weight or size. For some positively charged compounds, such as rhodamine B and lysozyme, the concentration in the capsules was orders of magnitude higher than that in the incubation solution. In addition, in vitro release study suggested that the encapsulated compounds could be released through a sustained manner to a certain degree. All these results point to the fact that these capsules might be used as novel delivery systems for some water-soluble compounds.
With an attempt to solubilize plasmid DNA (pDNA) in organic solvents, we developed nanocomplexation strategy by using block copolymer of polyethylene glycol-b-poly(L-lysine) (PEG-b-PLL). Self-assembly of PEG-b-PLL and pDNA in aqueous solution led to spherical nanocomplexes with core-shell structure when the +/- charge ratio (N/P) was higher than 1:1. This complexation had no significant impact on the helical structure of pDNA. After lyophilization, PEG-b-PLL/pDNA nanocomplexes originally formed in aqueous solution could be well dispersed in organic solvents such as THF and dichloromethane. Facilitating by nanocomplexation, pDNA could be encapsulated into PLGA nanoparticles with high efficiency, via oil-in-water emulsion solvent evaporation method. This complexation mediated pDNA solubilization in organic solvents may facilitate the development of novel nano- and micro-platforms for gene delivery.
Highly efficient nanomedicines were successfully fabricated by the indomethacin (IND) directed self-assembly of ?-cyclodextrin (?-CD)-conjugated polyethyleneimine (PEI-CD), taking advantage of the multiple interactions between drug and polymer. These nanoscaled assemblies exhibited spherical shape and positively charged surface. Compared with the commercial tablet, the relative oral bioavailability of IND-nanomedicines was significantly enhanced. Evaluation based on either carrageenan-induced paw edema or complete Freunds adjuvant (CFA)-induced arthritis suggested the newly developed nanomedicines were more effective than raw IND or IND tablet in terms of prophylactic effect and therapeutic activity. Even the low dose of nanomedicines offered the comparable results to those of control groups at the high dosage in most cases. Moreover, the nanoformulation exhibited ameliorated gastrointestinal stimulation. All these positive results indicated that this type of nanomedicines might serve as a highly efficient and effective delivery nanoplatform for the oral delivery of water-insoluble therapeutics.
The assembly of homostructured polypeptides bearing various side groups into well-defined nanostructures was presented, with their size and topology mainly dominated by the chemical structure and molecular weight of peptides. Pharmacokinetic and pharmacodynamic studies based on rat models suggested these newly constructed nanoassemblies with low cytotoxicity may function as novel nanoplatforms to efficiently and safely deliver therapeutics to achieve better efficacy but lower side effects. Other applications in biomedical fields, such as biotechnology, medical imaging, and tissue engineering, may also be expected.
It has been demonstrated that cerebral ischemia induces astrocyte reactivity, and subsequent glial scar formation inhibits axonal regeneration during the recovery phase. Investigating the mechanism of glial scar formation will facilitate the development of strategies to improve axonal regeneration. However, an in vitro model of ischemia-induced glial scar has not yet been systematically established.
We report the synthesis of a hydrophilic copolymer with one polyethylene glycol (PEG) block and one ?-cyclodextrin (?-CD) containing block by a "click" reaction between azido-substituted ?-CD and propargyl flanking copolymer. (1)H NMR study suggested a highly efficient conjugation of ?-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.
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