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1.
Int J Pharm ; 585: 119478, 2020 Jul 30.
Article in English | MEDLINE | ID: mdl-32473370

ABSTRACT

Antimicrobial resistance (AMR) has become a global health problem. Bacteria are able to adapt to different environments, with the presence or absence of a host, forming colonies and biofilms. In fact, biofilm formation confers chemical protection to the microbial cells, thus making most of the conventional antibiotics ineffective. Prevention and destruction of biofilms is a challenging task that should be addressed by a multidisciplinary approach from different research fields. One of the medical strategies used against biofilms is the therapy with drug delivery systems. Lipidic nanovesicles are a good choice for encapsulating drugs, increasing their pharmacodynamics and reducing side effects. These soft nanovesicles show significant advantages for their high biocompatibility, physical and chemistry properties, good affinity with drugs, and easy route of administration. This review summarizes the current knowledge on different types of vesicles which may be used as antibiotic carriers. The main preparation and purification methods for the synthesis of these vesicles are also presented. The advantages of drug encapsulation are critically reviewed. In addition, recent works on endolysin formulations as novel, "greener" and efficient antibiofilm solution are included. This paper can provide useful background for the design of novel efficient formulations and synergistic nanomaterials and could be also useful at the pharmaceutical industry to develop wastewater treatments and reduce the antibiotics in the environmental waters.


Subject(s)
Anti-Bacterial Agents/chemical synthesis , Chemistry, Pharmaceutical/methods , Drug Carriers/chemical synthesis , Drug Resistance, Bacterial/drug effects , Animals , Anti-Bacterial Agents/administration & dosage , Drug Carriers/administration & dosage , Drug Resistance, Bacterial/physiology , Humans , Liposomes , Micelles , Nanoparticles/administration & dosage , Nanoparticles/chemistry , Nanostructures/administration & dosage , Nanostructures/chemistry
2.
Analyst ; 145(7): 2716-2724, 2020 Apr 07.
Article in English | MEDLINE | ID: mdl-32107509

ABSTRACT

Cobalt(ii) phthalocyanine (CoPc) was suspended in aqueous medium and the colloidal system was used as catalyst for the electrochemical determination of hydrogen peroxide on paper-based electrodes modified with carbon nanomaterials. H2O2 was oxidised at 0.275 V vs. Ag pseudoreference electrode. This system was adapted to develop a glucose sensor with glucose oxidase immobilized on the cellulose electrode. CoPc suspended nanoparticles acted as nanoenzyme mimicking peroxidase activity and were combined with different carbon nanomaterials to form hybrids with optimised catalytic performance. GO-CoPc paper-based electrodes yielded the best results with a linear range of ∼12 µM to 49 mM for H2O2 and 0.1 mM to 1 mM for glucose. Glucose was determined in physiological serum and juice samples with recoveries of 93.3 and 94.2% respectively. CoPc could replace HRP for the catalytic sensing of H2O2, without the need to be dissolved. This material can be used in situ in a simple protocol with other nanomaterials for electrode modification. The sensor described has the advantage of easy preparation, using the catalyst in colloidal form, long term stability, and versatility to be adapted to other low cost and disposable enzymatic systems.


Subject(s)
Biosensing Techniques/methods , Colloids/chemistry , Glucose/analysis , Hydrogen Peroxide/analysis , Indoles/chemistry , Organometallic Compounds/chemistry , Paper , Electrochemical Techniques , Electrodes , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Fruit and Vegetable Juices/analysis , Glucose Oxidase/chemistry , Glucose Oxidase/metabolism , Nanoparticles/chemistry , Reproducibility of Results
3.
Anal Chim Acta ; 1074: 89-97, 2019 Oct 03.
Article in English | MEDLINE | ID: mdl-31159943

ABSTRACT

This work describes the development of a paper-based platform for highly sensitive detection of diclofenac. The quantification of this anti-inflammatory drug is of importance in clinical (e.g. quality and therapeutic control) and environmental (e.g. emerging contaminant determination) areas. The easy-to-handle platform here described consists of a carbon-ink paper-based working electrode and two metallic wires, provided by a gold-plated standard connector, as reference and counter electrodes. The porous paper matrix enables the preconcentration of the sample, decoupling sample and detection solutions. Thus, relatively large sample volumes can be used, which significantly improves the sensitivity of the method. A wide dynamic range of four orders of magnitude, between 0.10 and 100 µM, was obtained for diclofenac determination. Due to the predominance of adsorption at the lowest concentrations, there were two linear concentration ranges: one comprised between 0.10 and 5.0 µM (with a slope of 0.85 µA µM-1) and the other between 5.0 and 100 µM (with a slope of 0.48 µA µM-1). A limit of detection of 70 nM was achieved with this simple device that provided accurate results with an RSD of ca. 5%. The platform was applied for diclofenac quantification in spiked tap water samples. The versatility of this design enabled the fabrication of a multiplexed platform containing eight electrochemical cells that work independently. The low cost, small size and simplicity of the device allow on-site analysis, which is very useful for environmental monitoring.


Subject(s)
Anti-Inflammatory Agents/analysis , Diclofenac/analysis , Paper , Electrochemical Techniques/instrumentation , Electrochemical Techniques/methods , Electrodes , Equipment Design , Limit of Detection , Nanotubes, Carbon
4.
Biosens Bioelectron ; 87: 38-45, 2017 Jan 15.
Article in English | MEDLINE | ID: mdl-27517736

ABSTRACT

Extracellular vesicles (EVs) are membrane-bound nanovesicles delivered by different cellular lineages under physiological and pathological conditions. Although these vesicles have shown relevance as biomarkers for a number of diseases, their isolation and detection still has several technical drawbacks, mainly related with problems of sensitivity and time-consumed. Here, we reported a rapid and multiple-targeted lateral flow immunoassay (LFIA) system for the detection of EVs isolated from human plasma. A range of different labels (colloidal gold, carbon black and magnetic nanoparticles) was compared as detection probe in LFIA, being gold nanoparticles that showed better results. Using this platform, we demonstrated that improvements may be carried out by incorporating additional capture lines with different antibodies. The device exhibited a limit of detection (LOD) of 3.4×106EVs/µL when anti-CD81 and anti-CD9 were selected as capture antibodies in a multiple-targeted format, and anti-CD63 labeled with gold nanoparticles was used as detection probe. This LFIA, coupled to EVs isolation kits, could become a rapid and useful tool for the point-of-care detection of EVs, with a total analysis time of two hours.


Subject(s)
Antibodies, Immobilized/chemistry , Extracellular Vesicles/chemistry , Point-of-Care Systems , Tetraspanin 28/analysis , Tetraspanin 29/analysis , Antibodies, Monoclonal/chemistry , Biosensing Techniques , Equipment Design , Gold/chemistry , Gold Colloid/chemistry , Humans , Immunoassay/instrumentation , Immunoconjugates/chemistry , Limit of Detection , Magnetite Nanoparticles/chemistry , Metal Nanoparticles/chemistry
5.
Anal Bioanal Chem ; 378(8): 1922-8, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15064901

ABSTRACT

This article summarises our work on the development of voltammetric sensors based on molecularly imprinted polymers. Several recognition elements and integration strategies were used:1.membranes electropolymerised at the electrode surface; 2.casting of polymeric membranes by drop-coating a solution of pre-formed polymer (polyphosphazene) and template in a low-boiling-point solvent on to the electrode surface; 3.preparation of composite membranes containing conductive material (graphite or carbon black), acrylic-type molecularly imprinted polymers (small particle size), and PVC as binder; and 4.in-situ polymerisation of a thin layer of acrylic imprinted polymer deposited on the electrode surface by spin coating. All the options evaluated offer the possibility of controlling electrode characteristics such as hydrophobic/hydrophilic character, permeability, or film thickness, which are essential for obtaining good sensor performance.


Subject(s)
Chemistry Techniques, Analytical/instrumentation , Chemistry Techniques, Analytical/methods , Polymers/chemistry , Polymers/chemical synthesis , Electrochemistry , Electrodes , Molecular Structure , Organophosphorus Compounds/chemistry , Plastics/chemical synthesis , Plastics/chemistry
6.
Biosens Bioelectron ; 18(4): 353-62, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12604252

ABSTRACT

Despite the increasing number of applications of molecularly imprinted polymers (MIPs) in analytical chemistry, the construction of a biomimetic voltammetric sensor remains still challenging. This work investigates the development of a voltammetric sensor for vanillylmandelic acid (VMA) based on acrylic MIP-modified electrodes. Thin layers of MIPs for VMA have been prepared by spin coating the surface of a glassy carbon electrode with the monomers mixture (template, methacrylic acid, a cross-linking agent and solvent), followed by in situ photopolymerisation. After extraction of the template molecule, the peak current recorded with the imprinted sensor after rebinding was linear with VMA concentration in the range 19-350 microg ml(-1), whereas the response of the control electrode is independent of incubation concentration, and was about one-tenth of the value recorded with the imprinted sensor at the maximum concentration tested. Under the conditions used, the sensor is able to differentiate between VMA and other closely structural-related compounds, such as 3-methoxy-4-hydroxyphenylethylene glycol (not detected), or 3,4- and 2,5-dihydroxyphenilacetic acids, which are adsorbed on the bare electrode surface but not at the polymer layer. Homovanillic acid was detected with the imprinted sensors after incubation, indicating that the presence of both methoxy and carboxylic groups in the same position as in VMA is necessary for effective binding in the imprinted sites. Nevertheless, both species can be differentiated by the oxidation potential. It can be concluded that MIP-based voltammetric electrodes are very promising analytical tool for the development of highly selective analytical sensors.


Subject(s)
Biomimetic Materials/chemical synthesis , Coated Materials, Biocompatible/chemical synthesis , Electrochemistry/instrumentation , Electrodes , Methacrylates , Transducers , Vanilmandelic Acid/analysis , Electrochemistry/methods , Equipment Design , Equipment Failure Analysis , Polymers , Reproducibility of Results , Sensitivity and Specificity
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