New generation of electrochemical immunoassay based on polymeric nanoparticles for early detection of breast cancer

Screening and early diagnosis are the key factors for the reduction of mortality rate and treatment cost of cancer. Therefore, sensitive and selective methods that can reveal the low abundance of cancer biomarkers in a biological sample are always desired. Here, we report the development of a novel electrochemical biosensor for early detection of breast cancer by using bioconjugated self-assembled pH-responsive polymeric micelles. The micelles were loaded with ferrocene molecules as "tracers" to specifically target cell surface-associated epithelial mucin (MUC1), a biomarker for breast and other solid carcinoma. The synthesis of target-specific, ferrocene-loaded polymeric micelles was confirmed, and the resulting sensor was capable of detecting the presence of MUC1 in a sample containing about 10 cells/mL. Such a high sensitivity was achieved by maximizing the loading capacity of ferrocene inside the polymeric micelles. Every single event of binding between the antibody and antigen was represented by the signal of hundreds of thousands of ferrocene molecules that were released from the polymeric micelles. This resulted in a significant increase in the intensity of the ferrocene signal detected by cyclic voltammetry

Spirobifluorene-based polymers of intrinsic microporosity for the adsorption of methylene blue from wastewater: effect of surfactants

Owing to their high surface area and superior adsorption properties, spirobifluorene polymers of intrinsic microporosity (PIMs), namely PIM-SBF-Me (methyl) and PIM-SBF-tBu (tert-butyl), were used for the first time, to our knowledge, for the removal of methylene blue (MB) dye from wastewater. Spirobifluorene PIMs are known to have large surface area (can be up to 1100 m2 g−1) and have been previously used mainly for gas storage applications. Dispersion of the polymers in aqueous solution was challenging owing to their extreme hydrophobic nature leading to poor adsorption efficiency of MB. For this reason, cationic (cetyl-pyridinium chloride), anionic (sodium dodecyl sulfate; SDS) and non-ionic (Brij-35) surfactants were used and tested with the aim of enhancing the dispersion of the hydrophobic polymers in water and hence improving the adsorption efficiencies of the polymers. The effect of surfactant type and concentration were investigated. All surfactants offered a homogeneous dispersion of the polymers in the aqueous dye solution; however, the highest adsorption efficiency was obtained using an anionic surfactant (SDS) and this seems owing to the predominance of electrostatic interaction between its molecules and the positively charges dye molecules. Furthermore, the effect of polymer dosage and initial dye concentration on MB adsorption were also considered. The kinetic data for both polymers were well described by a pseudo-second-order model, while the Langmuir model better simulated the adsorption process of MB dye on PIM-SBF-Me and the Freundlich model was more suitable for PIM-SBF-tBu. Moreover, the maximum adsorption capacities recorded were 84.0 and 101.0 mg g−1 for PIM-SBF-Me and PIM-SBF-tBu, respectively. Reusability of both polymers was tested by performing three adsorption cycles and the results substantiate that both polymers can be effectively re-used with insignificant loss of their adsorption efficiency (®). These preliminary results suggested that incorporation of a surfactant to enhance the dispersion of hydrophobic polymers and adsorption of organic contaminants from wastewater is a simple and cost-effective approach that can be adapted for many other environmental applications

Selective adsorption of cationic dye utilizing poly (methacrylic acid-co-ethylene dimethacrylate) monolith from wastewater

In this study, poly(methacrylic acid-co-ethylene dimethacrylate (poly(MAA-co-EDMA)) monolith was prepared for the selective adsorption of acidic dye namely methylene blue (MB) from wastewater. The fabrication of the monolith was carried out by photoinitiation polymerization by irradiating a mixture methacrylic acid (MAA), ethylene dimethacrylate (EDMA), porogenic solvents and an initiator. Batch adsorption assays were performed to examine the impact of monolith dosage and initial dye concentration on the adsorption capacity and efficiency of the monolith towards MB dye molecules. Adsorption kinetic study revealed that MB adsorption on the monolith followed pseudo-second-order model and equilibrium adsorption behavior was best modeled by Langmuir adsorption isotherm with a maximum adsorption capacity of 50.00 mg g-1. Owe to the presence of negative binding sites on the monolith, cationic MB molecules are selectively adsorbed from MB/MO mixture with adsorption efficiency of 99.54% at equilibrium time. Finally, the monolith effectively adsorbed MB from the tap water in presence of competing ions and the maximum adsorptive capacity obtained was 47.62 mg g-1 with 84.5% adsorption efficiency. Hence, poly(MAA-co-EDMA) monolith is an adequate sorbent for the treatment of cationic dyes in the presence of other dyes and competing ions from wastewater

Origami Chips: Development and validation of a paper-based Lab-on-a-Chip device for the rapid and cost-effective detection of 4-methylmethcathinone (mephedrone) and its metabolite, 4-methylephedrine in urine

4-methylmethcathinone (mephedrone) has emerged in drug seizures as a new psychoactive substance (NPS) causing a public health risk of global concern. Currently, there are no commercial microfluidic devices for the selective detection of mephedrone and so this study presents a simple, low cost and portable paper-based Lab-on-a-Chip (LOC) device with colorimetric detection to fill this gap. Limits of detection for mephedrone in spiked urine and dissolved powder (aqueous) samples are clinically relevant at 4.34 ng mL-1 and 2.51 ng mL-1 respectively. No cross-reactivity for commonly encountered cutting agents, interferents and adulterants were detected. Mephedrone and its main metabolite were detectable in aqueous samples within 3 minutes. Stability and reproducibility measurements showed no significant difference in signal intensity over eight weeks and no significant difference within or between devices. The proposed device has the potential to provide cost-effective, rapid, on-site testing within forensic or clinical settings and therefore has wide global applicability

On-chip polyelectrolyte coating onto magnetic droplets-towards continuous flow assembly of drug delivery capsules

Polyelectrolyte (PE) microcapsules for drug delivery are typically fabricated via layer-by-layer (LbL) deposition of PE layers of alternating charge on sacrificial template microparticles, which usually requires multiple incubation and washing steps that render the process repetitive and time-consuming. Here, ferrofluid droplets were explored for this purpose as an elegant alternative of templates that can be easily manipulated via an external magnetic field, and require only a simple microfluidic chip design and setup. Glass microfluidic devices featuring T-junctions or flow focusing junctions for the generation of oil-based ferrofluid droplets in an aqueous continuous phase were investigated. Droplet size was controlled by the microfluidic channel dimensions as well as the flow rates of the ferrofluid and aqueous phases. The generated droplets were stabilised by a surface active polymer, polyvinylpyrrolidone (PVP), and then guided into a chamber featuring alternating, co-laminar PE solutions and wash streams, and deflected across them by means of an external permanent magnet. The extent of droplet deflection was tailored by the flow rates, the concentration of magnetic nanoparticles in the droplets, and the magnetic field strength. PVP-coated ferrofluid droplets were deflected through solutions of polyelectrolyte and washing streams using several iterations of multilaminar flow designs. This culminated in an innovative "Snakes-and-Ladders" inspired microfluidic chip design that overcame various issues of the previous iterations for the deposition of layers of anionic poly(sodium-4-styrene sulfonate) (PSS) and cationic poly(fluorescein isothiocyanate allylamine hydrochloride) (PAH-FITC) onto the droplets. The presented method demonstrates a simple and rapid process for PE layer deposition in <30 seconds, and opens the way towards rapid layer-by-layer assembly of PE microcapsules for drug delivery applications.The authors thank the Royal Embassy of Saudi Arabia Cultural Bureau in London and Albaha University in Saudi Arabia for funding. J.G.-P., E.B. and I.O. acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (project CTQ2015-66078-R (MINECO/FEDER) and FPI postgraduate research grant (BES-2013-064415). The authors thank Dr Stephen Clark for fabrication of the microfluidic devices

Novel and versatile solid-state chemiluminescence sensor based on TiO2-Ru(bpy)32+ nanoparticles for pharmaceutical drugs detection

This work describes a novel and versatile solid-state chemiluminescence sensor for analyte detection using TiO2-Ru(bpy)32+-Ce(IV). Herein, we report the synthesis, characterization, optimization and application of a new type of hybrid nanoparticles (NPs). Mesoporous TiO2-Ru(bpy)32+ NPs were prepared using a modified sol-gel method by incorporating Ru(bpy)32+ into the initial reaction mixture at various concentrations. The resultant bright orange precipitate was characterized via transmission electron microscopy, N2 sorpometry, inductively coupled plasma-optical emission spectrometer (ICP-OES), Raman and UV-Vis spectroscopy techniques. The concentration of Ru(bpy)32+ complex in the NPs was quantified using ICP-OES, and its chemiluminescence (CL) response was measured and compared with the same concentration in the liquid phase using oxalate as model analyte. The results showed that this type of hybrid material exhibited a higher CL signal compared with the liquid phase due to the enlarged surface area of the hybrid NPs (~149.6 m2/g). The amount of TiO2-Ru(bpy)32+ NPs and the effect of the analyte flow rate were also investigated to optimize the CL signal. The optimized system was further used to detect oxalate and two pharmaceutical drugs, namely, imipramine and promazine. The linear range for both drugs was 1–100 pm with limits of detection (LOD) of 0.1 and 0.5 pm, respectively. This approach is considered to be simple, low cost and facile and can be applied to a wide range of analytes

SALDI Substrate-Based FeNi Magnetic Alloy Nanoparticles for Forensic Analysis of Poisons in Human Serum

In this study, FeNi magnetic alloy nanoparticles (MANPs) were employed for the forensic analysis of four poisons&mdash;dimethametryn, napropamide, thiodicarb, and strychnine&mdash;using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). FeNi MANPs were prepared via coprecipitation using two reducing agents, sodium borohydride (NaBH4) and hydrazine monohydrate (N2H4&middot;H2O), to optimize the prepared MANPs and investigate their effect on the performance of SALDI-MS analysis. Thereafter, SALDI-MS analysis was carried out for the detection of three pesticides and a rodenticide. The prepared substrate offered sensitive detection of the targeted analytes with LOD values of 1 ng/mL, 100 pg/mL, 10 ng/mL, and 200 ng/mL for dimethametryn, napropamide, thiodicarb, and strychnine, respectively. The relative standard deviation (%RSD) values were in the range of 2.30&ndash;13.97% for the pesticides and 15&ndash;23.81% for strychnine, demonstrating the good spot-to-spot reproducibility of the FeNi substrate. Finally, the MANPs were successfully employed in the analysis of poison-spiked blood serum using a minute quantity of the sample with an LOD of 700 ng/mL dimethametryn and napropamide, 800 ng/mL thiodicarb, and 500 ng/mL strychnine. This study has great potential regarding the analysis of several poisons that may be found in human serum, which is significant in cases of self-harm