Kinetic parameters for small-molecule drug delivery by covalent cell surface targeting.

Human cells incubated with N-levulinoylmannosamine (ManLev) process this unnatural metabolic precursor into N-levulinoyl sialic acid (SiaLev), which is incorporated into cell surface glycoconjugates. A key feature of SiaLev is the presence of a ketone group that can be exploited in chemoselective ligation reactions to deliver small-molecule probes to the cell surface. A mathematical model was developed and tested experimentally to evaluate the prospects of using cell surface ketones as targets for covalent small-molecule drug delivery. We quantified the absolute number of ketone groups displayed on cell surfaces as a function of the concentration of ManLev in the medium. The apparent rate constants for the hydrolysis and disappearance of the cell surface conjugates were determined, as well as the apparent rate constant for the formation of covalent bonds with cell surface ketones. These values and the mathematical model confirm that chemoselective reactions on the cell surface can deliver to cells similar numbers of molecules as antibodies. Thus, cell surface ketones are a potential vehicle for a metabolically controlled small-molecule drug delivery system.     

Injectable microgel-hydrogel composites for prolonged small-molecule drug delivery

The design and application of soft nanocomposite injectable hydrogels containing entrapped microgels for small-molecule drug delivery is demonstrated. Copolymer microgels based on N-isopropylacrylamide and acrylic acid were synthesized that exhibited both ionic and hydrophobic affinity for binding to bupivacaine, a cationic local anesthetic used as a model drug. Microgels were subsequently immobilized within an in situ-gelling hydrogel network cross-linked via hydrazide-aldehyde chemistry to generate hydrogel-microgel soft nanocomposites. Drug release could be sustained for up to 60 days from these nanocomposite hydrogels, significantly longer than that achievable using the constituent hydrogel or microgels alone (<1 week). Drug release kinetics could be readily tuned by varying the affinity of the microgel and hydrogel phases for drug-polymer interactions and the network density of the hydrogel phase.     

AS1411 aptamer tagged PLGA-lecithin-PEG nanoparticles for tumor cell targeting and drug delivery

Liposomes and polymers are widely used drug carriers for controlled release since they offer many advantages like increased treatment effectiveness, reduced toxicity and are of biodegradable nature. In this work, anticancer drug‐loaded PLGA‐lecithin‐PEG nanoparticles (NPs) were synthesized and were functionalized with AS1411 anti‐nucleolin aptamers for site‐specific targeting against tumor cells which over expresses nucleolin receptors. The particles were characterized by transmission electron microscope (TEM) and X‐ray photoelectron spectroscopy (XPS). The drug‐loading efficiency, encapsulation efficiency and in vitro drug release studies were conducted using UV spectroscopy. Cytotoxicity studies were carried out in two different cancer cell lines, MCF‐7 and GI‐1 cells and two different normal cells, L929 cells and HMEC cells. Confocal microscopy and flowcytometry confirmed the cellular uptake of particles and targeted drug delivery. The morphology analysis of the NPs proved that the particles were smooth and spherical in shape with a size ranging from 60 to 110 nm. Drug‐loading studies indicated that under the same drug loading, the aptamer‐targeted NPs show enhanced cancer killing effect compared to the corresponding non‐targeted NPs. In addition, the PLGA‐lecithin‐PEG NPs exhibited high encapsulation efficiency and superior sustained drug release than the drug loaded in plain PLGA NPs. The results confirmed that AS1411 aptamer‐PLGA‐lecithin‐PEG NPs are potential carrier candidates for differential targeted drug delivery. Biotechnol. Bioeng. 2012; 109: 2920–2931. © 2012 Wiley Periodicals, Inc.     

Identification of novel small-molecule Ulex europaeus I mimetics for targeted drug delivery

Lectin mimetics have been identified that may have potential application towards targeted drug delivery. Synthetic multivalent polygalloyl constructs effectively competed with Ulex europaeus agglutinin I (UEA1) for binding to intestinal Caco-2 cell membranes.     

Nanofabricated biomimetic structures for smart targeting and drug delivery

We present a new approach to hybrid artificial cells (AC) designed for specific targeting and active drug delivery by combining an impermeable non-biological scaffold with an artificial bilayer lipid membrane (BLM) that supports the functioning bio-molecules required to provide AC functionality. We report on the fabrication of the scaffold using nanotechnology, as well as on loading of the scaffold and the functionalization of the AC. The results presented here are a first step towards the development of a biomimetic AC using nanotechnology.     

Targeted intracellular site-specific drug delivery: photosensitizer targeting to melanoma cell nuclei

A number of drugs are regarded as possessing local activity because their effects take place at an extremely short distance from their location site in the cell. The response of different cellular compartments to these effects is different. Such substances as photosensitizers (PSs), which are used in photodynamic cancer therapy, should be targeted to the cell compartments where their effect is the most pronounced. This study describes the construction and properties of the chimeric modular recombinant transporters (MRTs) expressed in Escherichia coli and used for PS targeting. These constructs include (1) the alpha-melanocyte-stimulating hormone as a ligand module, which is internalized by the target cells (mouse melanoma); (2) the optimized SV40 large T-antigen nuclear localization signal; (3) the hemoglobin-like protein from E. coli as a carrier module; (4) the endosomolytic module, the translocation domain of the diphtheria toxin. These MRTs were used for PS targeting to the mouse melanoma cell nuclei, the most PS-damaged intracellular compartment, which resulted in a PS photocytotoxic effect increase of several orders of magnitude. In our opinion, MRTs, which target locally active drugs into the desired cell compartment and thereby enhance the drug response, represent a new generation of the pharmacological agents.     

Multifunctional polymeric micelles with folate-mediated cancer cell targeting and pH-triggered drug releasing properties for active intracellular drug delivery

A new type of multifunctional polymeric micelle drug carrier for active intracellular drug delivery was prepared and characterized in this study. The micelle is a nano-supramolecular assembly with a spherical core-shell structure, and its surface and core were modified with piloting molecules for cancer cells and pH-sensitive drug binding linkers for controlled drug release, respectively. In order to prepare such micelles, self-assembling amphiphilic block copolymers, folate-poly(ethylene glycol)-poly(aspartate hydrazone adriamycin) [Fol-PEG-P(Asp-Hyd-ADR)], were specially designed and synthesized by installing a molecular promoter to enhance intracellular transport, folate (Fol), at the end of the shell-forming PEG chain and conjugating the anticancer drug, adriamycin (ADR), to the side chain of the core-forming PAsp segment through an acid-sensitive hydrazone bond. Because folate-binding proteins (FBP) are selectively overexpressed on the cancer cell membranes, the folate-bound micelles (FMA) can be guided to the cancer cells in the body, and after the micelles enter the cells, hydrazone bonds are cleaved by the intracellular acidic environment (pH 5-6) so that the drug release profile of the micelles is controlled pH-dependently. In this regard, FBP-binding selectivity of the prepared FMA was evaluated by surface plasmon resonance (SPR) measurements. The tetrazolium dye method (MTT assay) using human pharyngeal cancer cells (KB cell) revealed that FMA significantly improved cell growth inhibitory activity in spite of a short exposure time due to the selective and strong interaction between folate molecules and their receptors. Subsequent flow cytometric analysis showed that cellular uptake of FMA significantly increased. Consequently, these findings would provide one of the most effective approaches for cancer treatment using intracellular environment-targeting supramolecular drug carriers.     

Multifunctionality of lipid-core micelles for drug delivery and tumour targeting

Abstract

Phospholipid micelles have proven to be the versatile pharmaceutical nanocarrier of choice for the delivery of poorly soluble chemotherapeutics for cancer therapy using various treatment modalities. Phospholipid micelles are typically expected to increase the accumulation of the loaded drugs in tumour tissues by taking advantage of the enhanced permeability and retention effect and by ligand-mediated active targeting. Furthermore, by tailoring the composition of the micelles, it is possible to enhance the intracellular delivery of the cargo. This review highlights the important advancements in our laboratory with polyethyleneglycol phosphatidylethanolamine (PEG-PE)-based micellar drug delivery systems for improvement of the therapeutic efficacy of poorly soluble anticancer drugs.     

Multifunctionality of lipid-core micelles for drug delivery and tumour targeting

Phospholipid micelles have proven to be the versatile pharmaceutical nanocarrier of choice for the delivery of poorly soluble chemotherapeutics for cancer therapy using various treatment modalities. Phospholipid micelles are typically expected to increase the accumulation of the loaded drugs in tumour tissues by taking advantage of the enhanced permeability and retention effect and by ligand-mediated active targeting. Furthermore, by tailoring the composition of the micelles, it is possible to enhance the intracellular delivery of the cargo. This review highlights the important advancements in our laboratory with polyethyleneglycol phosphatidylethanolamine (PEG-PE)-based micellar drug delivery systems for improvement of the therapeutic efficacy of poorly soluble anticancer drugs.     

Potential of cell penetrating peptides for cell drug delivery

The interest of the scientific community for cell penetrating peptides (CPP) has been growing exponentially for these last years, and the list of novel CPP is increasing. These peptides are powerful tools for the delivery of cargoes to their site of action. Indeed, several drugs that cannot translocate through the cell plasma membrane have been successfully delivered into cells when grafted to a CPP. Various cargoes have been linked to CPP, such as oligonucleotides, pharmacologically active drugs, contrast agents for imaging, or nanoparticles as platforms for multigrafting purposes… This review illustrates the fabulous potential of CPP and the diversity of their use, but their most interesting application appears their future clinical use for the treatment of various pathological conditions.     

Redirecting lipoic acid ligase for cell surface protein labeling with small-molecule probes

Live cell imaging is a powerful method to study protein dynamics at the cell surface, but conventional imaging probes are bulky, or interfere with protein function, or dissociate from proteins after internalization. Here, we report technology for covalent, specific tagging of cellular proteins with chemical probes. Through rational design, we redirected a microbial lipoic acid ligase (LplA) to specifically attach an alkyl azide onto an engineered LplA acceptor peptide (LAP). The alkyl azide was then selectively derivatized with cyclo-octyne conjugates to various probes. We labeled LAP fusion proteins expressed in living mammalian cells with Cy3, Alexa Fluor 568 and biotin. We also combined LplA labeling with our previous biotin ligase labeling, to simultaneously image the dynamics of two different receptors, coexpressed in the same cell. Our methodology should provide general access to biochemical and imaging studies of cell surface proteins, using small fluorophores introduced via a short peptide tag.     

A model ternary heparin conjugate by direct covalent bond strategy applied to drug delivery system

A model ternary heparin conjugate by direct covalent bond strategy has been developed, in which modified heparin using active mix anhydride as intermediate conjugates with model drug molecule and model specific ligand, respectively. Designed ester bonds between model drug and heparin facilitate hydrolysis kinetics research. The strategy can be extended to design and synthesize a targeted drug delivery system. The key point is to use mixed anhydride groups as activating intermediates to mediate the synthesis of the ternary heparin conjugate. Formation of mixed anhydride is detected by the conductimetry experiment. The ternary heparin conjugate is characterized by ¹³C NMR, FT-IR and GPC, respectively. The decreased trend on degree of substitution (DS) is consistent with that of introduced anticancer drug and specific ligand in drug delivery system. Moreover, their anticoagulant activity is evaluated by measuring activated partial thromboplastin time (APTT) and anti-factor Xa activity. The results show that model ternary heparin conjugate with reduced anticoagulant activity may avoid the risk of severe hemorrhagic complication during the administration and is potential to develop a safe and effective drug delivery system on anticancer research.     

Multiscale modeling of protein membrane interactions for nanoparticle targeting in drug delivery

The objective is to develop easily computable and physiologically predictive mechanism-based multiscale pharmacodynamic models for targeted drug delivery.

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发现靶向蛋白质间相互作用的小分子药物研究进展

蛋白质-蛋白质相互作用在多种细胞功能中具有重要的作用。靶向蛋白质-蛋白质相互作用已经成为新药发现的重要策略,但发现能阻断蛋白质-蛋白质相互作用的小分子药物是一个巨大的挑战。尽管如此,近年来人们还是发现了许多能调控蛋白质-蛋白质相互作用的小分子。该文主要总结了在病毒进入、细胞凋亡通路和神经退行性疾病等方面的蛋白质-蛋白质相互作用小分子抑制剂的研究进展。     

Clostridial neurotoxins as a drug delivery vehicle targeting nervous system

Several neuronal disorders require drug treatment using drug delivery systems for specific delivery of the drugs for the targeted tissues, both at the peripheral and central nervous system levels. We describe a review of information currently available on the potential use of appropriate domains of clostridial neurotoxins, tetanus and botulinum, for effective drug delivery to neuronal systems. While both tetanus and botulinum neurotoxins are capable of delivering drugs the neuronal cells, tetanus neurotoxin is limited in clinical use because of general immunization of population against tetanus. Botulinum neurotoxin which is also being used as a therapeutic reagent has strong potential for drug delivery to nervous tissues.     

Selectins ligand decorated drug carriers for activated endothelial cell targeting

New active particulate polymeric vectors based on branched polyester copolymers of hydroxy-acid and allyl glycidyl ether were developed to target drugs to the inflammatory endothelial cell surface. The hydroxyl and carboxyl derivatives of these polymers allow grafting of ligand molecules on the polyester backbones at different densities. A known potent nonselective selectin ligand was selected and synthesized using a new scheme. This synthesis allowed the grafting of the ligand to the polyester polymers, preserving its binding activity as assessed by docking simulations. Selectin expression on human umbilical cord vascular endothelial cells (HUVEC) was induced with the pro-inflammatory bacterial lipopolysaccharide (LPS) or with the nonselective inhibitor of nitric oxide synthase L-NAME. Strong adhesion of the ligand decorated nanoparticles was evidenced in vitro on activated HUVEC. Binding of nanoparticles bearing ligand molecules could be efficiently inhibited by prior incubation of cells with free ligand, demonstrating that adhesion of the nanoparticles is mediated by specific interaction between the ligand and the selectin receptors. These nanoparticles could be used for specific drug delivery to the activated vascular endothelium, suggesting their application in the treatment of diseases with an inflammatory component such as rheumatoid arthritis and cancer.     

Physical blends of starch graft copolymers as matrices for colon targeting drug delivery systems

Colon targeting drug delivery systems have attracted many researchers due to the distinct advantages they present such as near neutral pH, longer transit time and reduced enzymatic activity. Moreover, in recent studies, colon specific drug delivery systems are gaining importance for use in the treatment of local pathologies of the colon and also for the systemic delivery of protein and peptide drugs.In previous works, our group has developed different types of hydrophilic matrices with grafted copolymers of starch and acrylic monomers with a wide range of physicochemical properties which have demonstrated their ability in controlled drug release. Since the cost of synthesizing a new polymeric substance and testing for its safety is enormous, polymer physical blends are frequently used as excipients in controlled drug delivery systems due to their versatility. So, the aim of this work is to combine two polymers which offer different properties such as permeability for water and drugs, pH sensitivity and biodegradability in order to further enhance the release performance of various drugs. It was observed that these physical blend matrices offer good controlled release of drugs, as well as of proteins and present suitable properties for use as hydrophilic matrices for colon-specific drug delivery.     

Reactive oxygen species responsive nanoplatforms as smart drug delivery systems for gastrointestinal tract targeting

The pharmacological therapy for gastrointestinal (GI) diseases, such as inflammatory bowel diseases, continues to present challenges in targeting efficacy. The need for maximal local drug exposure at the inflamed regions of the GI tract has led research to focus on a disease-targeted drug delivery approach. Smart nanomaterials responsive to the reactive oxygen species (ROS) concentrated in the inflamed areas, can be formulated into nanoplatforms to selectively release the active compounds, avoiding unspecific drug delivery to healthy tissues and limiting systemic absorption. Recent developments of ROS-responsive nanoplatforms include combination with other materials to obtain multi-responsive systems and modifications/derivatization to increase the interactions with biological tissues, cell uptake and targeting. This review describes the applications of ROS-responsive nanosystems for on-demand drug delivery to the GI tract.     

Response surface methodology for the optimization of ubiquinone self-nanoemulsified drug delivery system

The aim of the present study was to prepare and evaluate an optimized, self-nanoemulsified drug delivery system of ubiquinone. A 3-factor, 3-level Box-Behnken design was used for the optimization procedure with the amounts of Polyoxyl 35 castor oil (X₁), medium-chain mono- and diglyceride (X₂), and lemon oil (X₃) as the independent variables. The response variable was the cumulative percentage of ubiquinone emulsified in 10 minutes. Different ubiquinone release rates were obtained. The amount released ranged from 11% to 102.3%. Turbidity profile revealed 3 regions that were used to describe the progress of emulsion formation: lag phase, pseudolinear phase, and plateau turbidity. An increase in the amount of surfactant decreased turbidity values and caused a delay in lag time. Addition of cosurfactant enhanced the release rates. Increasing the amount of the eutectic agent was necessary to overcome drug precipitation especially at higher loading of surfactants and cosurfactants. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The regression equation generated for the cumulative percentage emulsified in 10 minutes was Y1=90.9–22.1X₁+5.03X₂+13.95X₃+12.13X₁X₂+15.13X₁X₃-14.40X₁ ²-6.25X₃ ². The optimization model predicted a 93.4% release with X₁, X₂, and X₃ levels of 35, 35, and 30 respectively. The observed responses were in close agreement with the predicted values of the optimized formulation. This demonstrated the reliability of the optimization procedure in predicting the dissolution behavior of a self-emulsified drug delivery system. Published: February 8, 2002.