Rapid Photoinduced Self-Healing, Controllable Drug Release, Skin Adhesion Ability, and Mechanical Stability of Hydrogels Incorporating Linker-Modified Gold Nanoparticles and Nanogels.

Appropriately modified thermoresponsive hydrogels, such as poly(-isopropylacrylamide) hydrogels, bring an opportunity for a variety of biomedical applications. Incorporating compounds with different properties into poly(-isopropylacrylamide) hydrogels offers opportunities to enhance their mechanical, self-healing ability, adhesiveness, thermal responsiveness, and drug release capabilities. In this study, we investigated the influence of Au-sulfur interactions on the properties of the poly(-isopropylacrylamide) hydrogels after introducing -bis(acryloyl)cystine (a newly synthesized cross-linker), modified gold nanoparticles, and a p(NIPAm-BISS) nanogel into the hydrogel matrix.

Enzyme-triggered- and tumor-targeted delivery with tunable, methacrylated poly(ethylene glycols) and hyaluronic acid hybrid nanogels.

Enzyme-responsive polymeric-based nanostructures are potential candidates for serving as key materials in targeted drug delivery carriers. However, the major risk in their prolonged application is fast disassembling of the short-lived polymeric-based structures. Another disadvantage is the limited accessibility of the enzyme to the moieties that are located inside the network.

Activity of Povidone in Recent Biomedical Applications with Emphasis on Micro- and Nano Drug Delivery Systems.

Due to the unwanted toxic properties of some drugs, new efficient methods of protection of the organisms against that toxicity are required. New materials are synthesized to effectively disseminate the active substance without affecting the healthy cells. Thus far, a number of polymers have been applied to build novel drug delivery systems.

Degradable nanohydrogel with high doxorubicin loadings exhibiting controlled drug release and decreased toxicity against healthy cells.

A new nanogel/drug carrier of 100-150 nm size, based on poly(N-isopropylacrylamide-co-sodium acrylate) and degradable crosslinker (cystine derivative), was synthesized. Using the electrostatic interactions between the carboxylic groups in the polymer network and the protonated amine groups of doxorubicin it was possible to load the drug into the carrier to a very high level of 28-30% relative to the dry mass of the polymer. The presence of the -S-S- groups made the polymer network susceptible to degradation by glutathione.

Synthesis of cross-linked poly(acrylic acid) nanogels in an aqueous environment using precipitation polymerization: unusually high volume change.

For the first time, by using precipitation polymerization in an aqueous solution, a cross-linked poly(acrylic acid)-(pAA) nanogel was synthesized. pAA was synthesized and cross-linked with ,'-methylenebisacrylamide (BIS) at 70°C in an acidified environment (pH 2) and containing 0.7 M NaCl using potassium persulfate as the initiator.

Degradable, thermo-, pH- and redox-sensitive hydrogel microcapsules for burst and sustained release of drugs.

Polymer microcapsules offer a possibility of storing increased amounts of drugs. Appropriate design and composition of the microcapsules allow tuning of the drug-release process. In this paper, we report on synthesis of hydrogel microcapsules sensitive to temperature and pH and degradable by glutathione and hydrogen peroxide.

Recent Advances in Degradable Hybrids of Biomolecules and NGs for Targeted Delivery.

Recently, the fast development of hybrid nanogels dedicated to various applications has been seen. In this context, nanogels incorporating biomolecules into their nanonetworks are promising innovative carriers that gain great potential in biomedical applications. Hybrid nanogels containing various types of biomolecules are exclusively designed for: improved and controlled release of drugs, targeted delivery, improvement of biocompatibility, and overcoming of immunological response and cell self-defense.

Switchable conformational changes of DNA nanogel shells containing disulfide-DNA hybrids for controlled drug release and efficient anticancer action.

Oligonucleotide strands containing dithiol (-SS-) groups were used as the co-crosslinkers in PNIPA-AAc based nanogels (NGs). They hybridized with PEG-oligonucleotides introduced into the gels. The specific DNA hybrid formed in the nanogel/nanocarrier was involved in highly efficient accumulation of intercalators.

Triggering the Shrinking/Swelling Process in Thin Gel Layers on Conducting Surfaces by Applying an Appropriate Potential.

Negatively charged, pH-sensitive, very thin gel layers with accumulated hexaammineruthenium (II)/(III) were deposited on conducting surfaces. The gel was synthesized by applying an electrochemically induced free-radical polymerization method. This method allowed covering the electrode surface with an uniform and compact layer.

Nanoconjugates of ferrocene and carbon-encapsulated iron nanoparticles as sensing platforms for voltammetric determination of ceruloplasmin in blood.

The nanoparticles comprising of iron core and carbon shell were decorated with ferrocene derivatives: ferrocenecarboxaldehyde (Fc-1) and ferrocenecarboxaldehyde oxime (Fc-2). A microdrop of suspension of the nanoconjugate was placed on a glassy-carbon electrode to prepare the recognition/sensing layer. Drying and purification of the sensing layer resulted in a well-defined and stable square-wave voltammogram of the ferrocene moiety.

A degradable nanogel drug carrier crosslinked with three-oligonucleotide hybrids for two-way drug release in mild and high hyperthermia treatment.

Three-segment oligonucleotide hybrids were introduced as crosslinkers to a PNIPA-AAc nanonetwork. The obtained nanogels could be specifically transformed and degraded. The specific architecture of the presented carrier aims at achieving effective cancer treatment with reduced side toxicity.

Nanohydrogel with N,N'-bis(acryloyl)cystine crosslinker for high drug loading.

Substantially improved hydrogel particles based on poly(N-isopropylacrylamide) (pNIPA) have been obtained. First, as a result of replacing commercially available N,N'-bis(acryloyl)cystamine (BAC), the crosslinker, with acryloyl derivative of cystine containing a carboxylic group (BISS), the hydrogel particles acquired improved stability vs. ionic strength and allowed further chemical modification of the chains, including the attachment of drug molecules.

Conformational control of human transferrin covalently anchored to carbon-coated iron nanoparticles in presence of a magnetic field.

Unlabelled: The control of the interactions of proteins with the support matrix plays a key role in medicine, drug delivery systems and diagnostics. Herein, we report that covalent anchoring of human transferrin to carbon-coated iron magnetic nanoparticles functionalized with carboxylic groups (Fe@C-COOH Nps) in the presence of magnetic field results in its conformational integrity and electroactivity. We have found that, the direct contact of human transferrin with Fe@C-COOH Nps does not lead to release of iron and in consequence to the irreversible conformational changes of the protein.

Electrochemical Examination of the Structure of Thin Hydrogel Layers Anchored to Regular and Microelectrode Surfaces.

For the examination of hydrogel structure, thin layers of thermoresponsive gels based on poly(N-isopropylacrylamide) (pNIPA) and copolymer poly(N-isopropylacrylamide-co-sodium acrylate) (p(NIPA-co-AS)) were successfully anchored to microelectrode and regular electrode surfaces using the electrochemically induced free radical polymerization. The obtained layers were stable and covered the entire surface of the electrodes. Electroactive probes 1,1'-ferrocenedimethanol (Fc(CH2OH)2) and synthesized derivatives of ferrocene modified with polyethylene glycol units (Fc-PEGn) of various length (n = 4, 9, 75, and 135) were employed for studying the volume phase transition of the thin hydrogel layers and for the determination of their structural parameters.

Improved cytotoxicity and preserved level of cell death induced in colon cancer cells by doxorubicin after its conjugation with iron-oxide magnetic nanoparticles.

A promising strategy for overcoming the problem of limited efficacy in antitumor drug delivery and in drug release is the use of a nanoparticle-conjugated drug. Doxorubicin (Dox) anticancer chemotherapeutics has been widely studied in this respect, because of severe cardiotoxic side effects. Here, we investigated the cytotoxic effects, the uptake process, the changes in cell cycle progression and the cell death processes in the presence of iron-oxide magnetic nanoparticles (Nps) and doxorubicin conjugates (Dox-Nps) in human colon HT29 cells.

Electrochemical examination of ability of dsDNA/PAM composites for storing and releasing of doxorubicin.

Composites consisting of ss- and ds-DNA strands and polyacrylamide (PAM) hydrogel have been synthesized. DNA was entrapped non-covalently. The obtained DNA biomaterial exhibited a strong increase in guanine and adenine anodic currents when temperature reached the physiological level.

Stable and degradable microgels linked with cystine for storing and environmentally triggered release of drugs.

Environmentally sensitive, degradable microgels based on poly(N-isopropylacrylamide) (pNIPA) cross-linked with the diacryloyl derivative of cystine (BISS) were synthesized by applying surfactant-free emulsion polymerization. pNIPA contributed the sensitivity to temperature to the microgels and the cross-linker made them degradable and sensitive to pH. The morphology of the microgels was investigated by using scanning and transmission electron microscopies (SEM and TEM).

Assembling Paramagnetic Ceruloplasmin at Electrode Surfaces Covered with Ferromagnetic Nanoparticles. Scanning Electrochemical Microscopy in the Presence of a Magnetic Field.

Adsorption of ceruloplasmin (Cp) at a gold electrode modified with ferromagnetic iron nanoparticles encapsulated in carbon (Fe@C Nps) leads to a successful immobilization of the enzyme in its electroactive form. The proper placement of Cp at the electrode surface on top of the nanocapsules containing an iron core allowed a preorientation of the enzyme, hence allowing direct electron transfer between the electrode and the enzyme. Laser ablation coupled with inductively coupled plasma mass spectrometry indicated that Cp was predominantly located at the paramagnetic nanoparticles.

Environmentally sensitive, quickly responding microgels with lattice channels filled with polyaniline.

A conducting microcomposite composed of cross-linked poly(N-isopropylacrylamide) (pNIPA) and polyaniline (PANI) was synthesized. First, pNIPA gel microcapsules were prepared via surfactant-free emulsion polymerization (SFEP). Then by soaking the gel with a solution of an oxidizing agent (sodium persulfate) and placing it in a solution of aniline in nitrobenzene the conducting polymer was formed in pNIPA.

Hydrogel with chains functionalized with carboxyl groups as universal 3D platform in DNA biosensors.

Application of hydrogel based on N-isopropylacrylamide with carboxyl groups grafted to the chains enabled the immobilization of DNA at an extent exceeding that for flat surfaces by at least one order of magnitude. The probe DNA strands in the 3D platform were fully available for the hybridization process. The examination of the gels containing different amounts of grafted carboxyl groups (1-10%) was done using quartz crystal microbalance, electrochemical impedance spectroscopy, chronoamperometry and ionic coupled plasma with laser ablation.

Quantifying uncertainty of determination by standard additions and serial dilutions methods taking into account standard uncertainties in both axes.

The analytical expressions for the calculation of the standard uncertainty of the predictor variable either extrapolated or interpolated from a calibration line that takes into account uncertainties in both axes have been derived and successfully verified using the Monte Carlo modeling. These expressions are essential additions to the process of the analyte quantification realized with either the method of standard additions (SAM) or the method of serial dilutions (MSD). The latter one has been proposed as an alternative approach to the SAM procedure.

Voltammetric and electrochemical gravimetric selective detection of interactions between Tl(I) and guanine and the influence on activity of DNA drug-intercalators.

The interactions of Tl(I), a well known toxic species, with selected oligonucleotides were examined. The oligonucleotide sequences selected for the investigation were taken from gene hOGG1 responsible for repairing of DNA damage. Cyclic voltammetry was particularly useful, since nitrogen N-7 in guanine can be electrooxidized while its binding with Tl(I) leads to the loss of electroactivity.

Progress in targeting tumor cells by using drug-magnetic nanoparticles conjugate.

To limit cytotoxicity of anticancer drugs against healthy cells, an appropriate carrier should be synthesized to deliver the drug to the tumor tissue only. A good solution is to anchor a magnetic nanoparticle to the molecule of the drug and to use a properly directed external magnetic field. The synthesis of the conjugate of doxorubicin with magnetic nanoparticles (iron oxide) modified by us resulted in a substantial depression of the aggregation process of the nanoparticles and therefore allowed the correct examination of cytotoxicity of the modified drug.

Chromium(VI) but not chromium(III) species decrease mitoxantrone affinity to DNA.

Binding of mitoxantrone (MXT) to double-stranded DNA has been investigated as a model drug-DNA binding system to evaluate the effects of various forms of chromium on the binding properties. We have found that Cr(III), which binds strongly to DNA, does not affect the MXT affinity to DNA. In contrast, Cr(VI), in the form of chromate ions CrO(4)(2-), decreases the MXT affinity to DNA despite electrostatic repulsions with phosphate-deoxyribose chains of DNA.

Oxidation of DNA followed by conformational change after OH radical attack.

Examination of the attack of OH radicals produced in the Fenton way on DNA molecules is important from biological, biochemical, and biosensor points of view. Calf thymus DNA was selected for the investigation, since this natural oligonucleotide is often used in examination of drug-DNA interactions. Particularly useful was the coherent application of five techniques: electrochemical quartz crystal microbalance (EQCM), square wave voltammetry (SWV), circular dichroism (CD), atomic force microscopy (AFM), and UV-vis spectroscopy.