This mini-review summarizes the development of the derivatives and conjugates of Amphotericin B (AMB) which have not been clinically applied so far but are therapeutically promising. Effects of chemical modifications of AMB upon biological activities of the resulting derivatives are discussed. The examples presented include variation of functional groups in AMB, covalent conjugates with other molecules, poly(ethylene glycols) and polysaccharides. Possibilities of targeted delivery of AMB are discussed.
In this critical review, we outline various covalent and non-covalent approaches for the functionalization of iron oxide nanoparticles (IONPs). Tuning the surface chemistry and design of magnetic nanoparticles are described in relation to their applicability in advanced medical technologies and biotechnologies including magnetic resonance imaging (MRI) contrast agents, targeted drug delivery, magnetic separations and immobilizations of proteins, enzymes, antibodies, targeting agents and other biosubstances. We review synthetic strategies for the controlled preparation of IONPs modified with frequently used functional groups including amine, carboxyl and hydroxyl groups as well as the preparation of IONPs functionalized with other species, e.g., epoxy, thiol, alkane, azide, and alkyne groups. Three main coupling strategies for linking IONPs with active agents are presented: (i) chemical modification of amine groups on the surface of IONPs, (ii) chemical modification of bioactive substances (e.g. with fluorescent dyes), and (iii) the activation of carboxyl groups mainly for enzyme immobilization. Applications for drug delivery using click chemistry linking or biodegradable bonds are compared to non-covalent methods based on polymer modified condensed magnetic nanoclusters. Among many challenges, we highlight the specific surface engineering allowing both therapeutic and diagnostic applications (theranostics) of IONPs and magnetic/metallic hybrid nanostructures possessing a huge potential in biocatalysis, green chemistry, magnetic bioseparations and bioimaging.
Composite materials based on a titanium support and a thin, alginate hydrogel could be used in bone tissue engineering as a scaffold material that provides biologically active molecules. The main objective of this contribution is to characterize the activation and the functionalization of titanium surfaces by the covalent immobilization of anchoring layers of self-assembled bisphosphonate neridronate monolayers and polymer films of 3-aminopropyltriethoxysilane and biomimetic poly(dopamine). These were further used to bind a bio-functional alginate coating. The success of the titanium surface activation, anchoring layer formation and alginate immobilization, as well as the stability upon immersion under physiological-like conditions, are demonstrated by different surface sensitive techniques such as spectroscopic ellipsometry, infrared reflection-absorption spectroscopy and X-ray photoelectron spectroscopy. The changes in morphology and the established continuity of the layers are examined by scanning electron microscopy, surface profilometry and atomic force microscopy. The changes in hydrophilicity after each modification step are further examined by contact angle goniometry.
- Publication type
- Journal Article MeSH
Nearly monodispersed superparamagnetic maghemite nanoparticles (15-20nm) were prepared by a one-step thermal decomposition of iron(II) acetate in air at 400 degrees C. The presented synthetic route is simple, cost effective and allows to prepare the high-quality superparamagnetic particles in a large scale. The as-prepared particles were exploited for the development of magnetic nanocomposites with the possible applicability in medicine and biochemistry. For the purposes of the MRI diagnostics, the maghemite particles were simply dispersed in the bentonite matrix. The resulting nanocomposite represents very effective and cheap oral negative contrast agent for MRI of the gastrointestinal tract and reveals excellent contrast properties, fully comparable with those obtained for commercial contrast material. The results of the clinical research of this maghemite-bentonite contrast agent for imaging of the small bowel are discussed. For biochemical applications, the primary functionalization of the prepared maghemite nanoparticles with chitosan was performed. In this way, a highly efficient magnetic carrier for protein immobilization was obtained as demonstrated by conjugating thermostable raffinose-modified trypsin (RMT) using glutaraldehyde. The covalent conjugation resulted in a further increase in trypsin thermostability (T(50)=61 degrees C) and elimination of its autolysis. Consequently, the immobilization of RMT allowed fast in-solution digestion of proteins and their identification by MALDI-TOF mass spectrometry.
The non-specific binding of non-target species to functionalized surfaces of biosensors continues to be challenge for biosensing in real-world media. Three different low-fouling and functionalizable surface platforms were employed to study the effect of functionalization on fouling resistance from several types of undiluted media including blood plasma and food media. The surface platforms investigated in this work included two polymer brushes: hydroxy-functional poly(2-hydroxyethyl methacrylate) (pHEMA) and carboxy-functional poly(carboxybetaine acrylamide) (pCBAA), and a standard OEG-based carboxy-functional alkanethiolate self-assembled monolayer (AT-SAM). The wet and dry polymer brushes were analyzed by AFM, ellipsometry, FT-IRRAS, and surface plasmon resonance (SPR). The surfaces were functionalized by the covalent attachment of antibodies, streptavidin, and oligonucleotides and the binding and biorecognition characteristics of the coatings were compared. We found that functionalization did not substantially affect the ultra-low fouling properties of pCBAA (plasma fouling of ~20 ng/cm(2)), a finding in contrast with pHEMA that completely lost its resistance to fouling after the activation of hydroxyl groups. Blocking a functionalized AT-SAM covalently with BSA decreased fouling down to the level comparable to unblocked pCBAA. However, the biorecognition capability of blocked functionalized AT-SAM was poor in comparison with functionalized pCBAA. Limits of detection of Escherichia coli O157:H7 in undiluted milk were determined to be 6×10(4), 8×10(5), and 6×10(5) cells/ml for pCBAA, pHEMA, and AT-SAM-blocked, respectively. Effect of analyte size on biorecognition activity of functionalized coatings was investigated and it was shown that the best performance in terms of overall fouling resistance and biorecognition capability is provided by pCBAA.
- MeSH
- Adsorption MeSH
- Acrylamides chemistry MeSH
- Escherichia coli isolation & purification MeSH
- Limit of Detection MeSH
- Milk microbiology MeSH
- Polyhydroxyethyl Methacrylate chemistry MeSH
- Polymers chemistry MeSH
- Surface Plasmon Resonance methods MeSH
- Surface Properties MeSH
- Sulfhydryl Compounds chemistry MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Anterior Gradient-2 (AGR2) is a component of a pro-oncogenic signalling pathway that can promote p53 inhibition, metastatic cell migration, limb regeneration, and cancer drug-resistance. AGR2 is in the protein-disulphide isomerase superfamily containing a single cysteine (Cys-81) that forms covalent adducts with its client proteins. We have found that mutation of Cysteine-81 attenuates its biochemical activity in its sequence-specific peptide docking function, reduces binding to Reptin, and reduces its stability in cells. As such, we evaluated how chemical oxidation of its cysteine affects its biochemical properties. Recombinant AGR2 spontaneously forms covalent dimers in the absence of reductant whilst DTT promotes dimer to monomer conversion. Mutation of Cysteine-81 to alanine prevents peroxide catalysed dimerization of AGR2 in vitro, suggesting a reactive cysteine is central to covalent dimer formation. Both biochemical assays and ESI mass spectrometry were used to demonstrate that low levels of a chemical oxidant promote an intermolecular disulphide bond through formation of a labile sulfenic acid intermediate. However, higher levels of oxidant promote sulfinic or sulfonic acid formation thus preventing covalent dimerization of AGR2. These data together identify the single cysteine of AGR2 as an oxidant responsive moiety that regulates its propensity for oxidation and its monomeric-dimeric state. This has implications for redox regulation of the pro-oncogenic functions of AGR2 protein in cancer cells.
- MeSH
- Drug Resistance, Neoplasm genetics MeSH
- Cysteine genetics metabolism MeSH
- Disulfides chemistry metabolism MeSH
- DNA Helicases chemistry genetics metabolism MeSH
- Mass Spectrometry MeSH
- Sulfenic Acids metabolism MeSH
- Humans MeSH
- MCF-7 Cells MeSH
- Protein Multimerization genetics MeSH
- Mutation MeSH
- Neoplasms chemistry genetics pathology MeSH
- Oxidation-Reduction * MeSH
- Proteins chemistry genetics metabolism MeSH
- Amino Acid Sequence genetics MeSH
- Signal Transduction MeSH
- Carrier Proteins chemistry genetics metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
OBJECTIVES: Ellipticine is an anticancer agent that functions through multiple mechanisms participating in cell cycle arrest and initiation of apoptosis. This drug forms covalent DNA adducts after its enzymatic activation with cytochrome P450 (CYP), which is one of the most important ellipticine DNA-damaging mechanisms of its cytotoxic effects. The improvements of cancer treatment are the major challenge in oncology research. Nanotransporters (nanoparticles) are promising approaches to target tumor cells, frequently leading to improve drug therapeutic index. Ellipticine has already been prepared in nanoparticle forms. However, since its anticancer efficiency depends on the CYP3A4-mediated metabolism in cancer cells, the aim of our research is to develop nanoparticles containing this enzyme that can be transported to tumor cells, thereby potentiating ellipticine cytotoxicity. METHODS: The CYP3A4 enzyme encapsulated into two nanoparticle forms, liposomes and microsomes, was tested to activate ellipticine to its reactive species forming covalent DNA adducts. Ellipticine-derived DNA adducts were determined by the 32P-postlabeling method. RESULTS: The CYP3A4 enzyme both in the liposome and microsome nanoparticle forms was efficient to activate ellipticine to species forming DNA adducts. Two DNA adducts, which are formed from ellipticine metabolites 12-hydroxy- and 13-hydroxyellipticine generated by its oxidation by CYP3A4, were formed by both CYP3A4 nanoparticle systems. A higher effectiveness of CYP3A4 in microsomal than in liposomal nanoparticles to form ellipticine-DNA adducts was found. CONCLUSION: Further testing in a suitable cancer cell model is encouraged to investigate whether the DNA-damaging effects of ellipticine after its activation by CYP3A4 nanoparticle forms are appropriate for active targeting of this enzyme to specific cancer cells.
- MeSH
- DNA Adducts metabolism MeSH
- Cytochrome P-450 CYP3A metabolism MeSH
- Ellipticines metabolism MeSH
- Antineoplastic Agents, Phytogenic metabolism MeSH
- Humans MeSH
- Liposomes * MeSH
- Microsomes * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The interaction of a double stranded small interference RNA (siRNA Nef) with cationic carbosilane dendrimers of generations 1-3 with two different ammonium functions at the periphery ([-NMe2R]+, R=Me, (CH2)2OH) has been studied by experimental techniques (zeta potential, electrophoresis, single molecule pulling experiments) and molecular dynamic calculations. These studies state the presence of different forces on dendriplex formation, depending on generation and type of ammonium group. Whilst for higher dendrimers electrostatic forces mainly drive the stability of dendriplexes, first generation compounds can penetrate into siRNA strands due to the establishment of hydrophobic interactions. Finally, in the particular case of first generation dendrimer [G1O3(NMe2(CH2)2OH))6]6+; the presence of hydroxyl groups reinforces dendriplex stability by hydrogen bonds formation. However, since these small dendrimers do not cover the RNA, only higher generation derivatives protect RNA from degradation.
- MeSH
- Dendrimers chemistry metabolism MeSH
- nef Gene Products, Human Immunodeficiency Virus antagonists & inhibitors chemistry genetics metabolism MeSH
- Hydrophobic and Hydrophilic Interactions MeSH
- Kinetics MeSH
- Leukocytes, Mononuclear cytology MeSH
- Humans MeSH
- RNA, Small Interfering chemistry genetics metabolism MeSH
- Molecular Conformation MeSH
- Primary Cell Culture MeSH
- Silanes chemistry metabolism MeSH
- Molecular Dynamics Simulation MeSH
- Drug Stability MeSH
- Static Electricity MeSH
- Gene Transfer Techniques * MeSH
- Thermodynamics MeSH
- Particle Size MeSH
- Hydrogen Bonding MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The aim of this study was to develop the potential tissue engineering applications of d-glucosamine (GlcN) immobilized onto the surface of a biodegradable matrix in order to induce a desired biological effect at biointerfaces. Thus, for sample preparation we used a novel multistep physicochemical approach. In the first step the poly(lactic acid) (PLA) films were exposed to a low pressure plasma in air atmosphere, followed by radical graft copolymerization with acrylic acid to yield a carboxyl-functionalized spacer layer on the PLA surface. The carboxyl groups were then coupled to GlcN molecules via the carbodiimide chemistry. The developed surfaces were characterized by X-ray Photoelectron Spectroscopy (XPS), Contact angle measurements and Atomic Force Microscopy (AFM). A preliminary study on the proliferation of fibroblasts on the developed surfaces was performed using the NIH/3T3 cell line.
- MeSH
- Biocompatible Materials chemistry MeSH
- Photoelectron Spectroscopy MeSH
- Glucosamine chemistry MeSH
- Microscopy, Atomic Force MeSH
- Polyesters chemistry MeSH
- Surface Properties MeSH
- Cell Proliferation MeSH
- Regeneration * MeSH
- Wettability MeSH
- Tissue Engineering * MeSH
- Publication type
- Journal Article MeSH
This study was aimed at verifying the hypothesis that acute kidney failure accompanying cisplatin administration in the cancer therapy could be due to cisplatin interaction with the cytoplasmic part of Na(+)/K(+)-ATPase. Our results demonstrated that cisplatin-binding caused inhibition of Na(+)/K(+)-ATPase, in contrast to other platinated chemotherapeutics such as carboplatin and oxaliplatin, which are known to be much less nephrotoxic. To acquire more detailed structural information, we performed a series of experiments with the isolated large cytoplasmic segment connecting transmembrane helices 4 and 5 (C45 loop) of Na(+)/K(+)-ATPase. Electrochemistry showed that cisplatin is bound to the cysteine residues of the C45 loop, mass spectrometry revealed a modification of the C45 peptide fragment GSHMASLEAVETLGSTSTICSDK, which contains the conserved phosphorylated residue Asp369. Hence, we hypothesize that binding of cisplatin to Cys367 can cause sterical obstruction during the phosphorylation or dephosphorylation step of the Na(+)/K(+)-ATPase catalytic cycle.
- MeSH
- Cisplatin metabolism pharmacology MeSH
- Protein Conformation MeSH
- Models, Molecular MeSH
- Cerebral Cortex enzymology MeSH
- Swine MeSH
- Antineoplastic Agents metabolism pharmacology MeSH
- Sodium-Potassium-Exchanging ATPase antagonists & inhibitors metabolism MeSH
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization MeSH
- Protein Binding MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
