Acoustic levitation and manipulation of columns of droplets with integrated optical detection for parallelisation of reactions.

The most common methodology for performing multiple chemical and biological reactions in parallel is to use microtitre plates with either manual or robotic dispensing of reactants and wash solutions. We envision a paradigm shift where acoustically levitated droplets serve as wells of microtitre plates and are acoustically manipulated to perform chemical and biological reactions in a non-contact fashion. This in turn requires that lines of droplets can be levitated and manipulated simultaneously so that the same operations (merge, mix, and detect) can be performed on them in parallel.

An investigative study into an oscillatory reaction in acoustically levitated droplets.

For the first time we have studied an oscillatory chemical reaction (the well-known Belousov-Zhabotinsky (BZ) reaction) in acoustically levitated droplets. Acoustically levitated droplets allow wall-less reaction studies, reduce consumption of sample/reagents, offer high throughput measurements, and enable environmentally friendly chemistry by significantly reducing plastic waste. In this work, microdroplets of the BZ reactants were mixed at the central axis of a low-cost acoustic levitator.

Hydrogel gratings with patterned analyte responsive dyes for spectroscopic sensing.

This is an unprecedented report of hydrogel gratings with an analyte responsive dye immobilised in alternating strips where the patterned dye is its own dispersive element to perform spectroscopy. At each wavelength, the diffraction efficiency of hydrogel gratings is a function of dye absorbance, which in turn is dependent on the concentration of analytes in samples. Thus, changes in intensity of diffracted light of hydrogel gratings were measured for sensing of analytes.

A study of diffraction-based chitosan leaky waveguide (LW) biosensors.

The waveguide layer of diffraction-based leaky waveguides (LWs) must be made of materials that have low refractive index, are permeable to analytes, can be deposited by spin coating, and can be functionalised and crosslinked. These requirements are fulfilled by thin films of chitosan hydrogels. In this work, we studied the reproducibility of diffraction-based LWs with chitosan waveguides.

A Self-Referenced Diffraction-Based Optical Leaky Waveguide Biosensor Using Photofunctionalised Hydrogels.

We report a novel self-referenced diffraction-based leaky waveguide (LW) comprising a thin (~2 µm) film of a photofunctionalisable hydrogel created by covalent attachment of a biotinylated photocleavable linker to chitosan. Streptavidin attached to the chitosan via the photocleavable linker was selectively removed by shining 365 nm light through a photomask to create an array of strips with high and low loading of the protein, which served as sensor and reference regions respectively. The differential measurements between sensor and reference regions were used for measuring analytes (i.

Optimization Synthesis and Biosensing Performance of an Acrylate-Based Hydrogel as an Optical Waveguiding Sensing Film.

The metal-clad leaky waveguide (MCLW) is an optical biosensor consisting of a metal layer and a low index waveguide layer on a glass substrate. This label-free sensor measures refractive index (RI) changes within the waveguide layer. This work shows the development and optimization of acrylate based-hydrogel as the waveguide layer formed from PEG diacrylate (PEGDA, M 700), PEG methyl ether acrylate (PEGMEA, M 480), and acrylate-PEG-NHS fabricated on a substrate coated with 9.

Disposable Injection Molded Conductive Electrodes Modified with Antimony Film for the Electrochemical Determination of Trace Pb(II) and Cd(II).

This work describes a novel electrochemical sensor fabricated by an injection molding process. This device features a conductive polymer electrode encased in a plastic holder and electroplated in situ with a thin antimony film. The antimony film sensor was applied to the determination of Pb(II) and Cd(II) by anodic stripping voltammetry (ASV).

A feasibility study of a leaky waveguide aptasensor for thrombin.

This proof-of-principle study demonstrates the feasibility of a leaky waveguide (LW) aptasensor, where aptamers were immobilised in a mesoporous chitosan waveguiding film for the detection of thrombin. This work has demonstrated that aptamers immobilised in hydrogels retain their affinity and selectivity towards their target and thus can be used as bioreceptors. The use of antibodies as bioreceptors for sensing thrombin is not viable because it is a serine protease, which will cleave the antibodies.

Method for Determining Average Iron Content of Ferritin by Measuring its Optical Dispersion.

We report a method where the refractive index increments of an iron storage protein, ferritin, and apoferritin (ferritin minus iron) were measured over the wavelength range of 450-678 nm to determine the average iron content of the protein. The protein used in this study had ∼3375 iron atoms per molecule. The measurement of optical dispersion over the broad wavelength range was enabled by the use of mesoporous leaky waveguides (LWs) made of chitosan.

Over two decades of orthopaedic surgery in patients with inhibitors-Quantifying the complication of bleeding.

Patients with haemophilia who have developed inhibitors against factor VIII (FVIII) or factor IX present a significant concern to those surgeons who operate on them. The evidence base for bypassing agents such as recombinant factor VIIa and activated prothrombin complex concentrate has amassed over several decades. The literature is open to positive interpretation on the successful use of these agents in the treatment of inhibitor-positive patients.

Microfluidic channel-assisted screening of hematopoietic malignancies.

A simple microfluidic fluorescence in situ hybridization (FISH) device allowing accurate analysis of interphase nuclei in 1 hr in narrow channels is presented. Photolithography and fluorosilicic acid etching were used to fabricate microfluidic channels (referred to as FISHing lines) that allowed analysis of 10 samples on a glass microscope slide 0.2 µl of sample volume was used to fill a micro-channel, which resembled a 250-fold reduction compared to conventional FISH.

Miniaturised free flow isotachophoresis of bacteria using an injection moulded separation device.

A new design of miniaturised free flow electrophoresis device has been produced. The design contains a separation chamber that is 45 mm long by 31.7 mm wide with a depth of 50 μm and has nine inlet and nine outlet holes to allow for fraction collection.

Is there Light at the End of the Tunnel? Controversies in the Diagnosis and Management of Carpal Tunnel Syndrome.

Carpal tunnel syndrome is a common disorder responsible for considerable patient suffering and cost to health services. Despite extensive research, controversies still exist with regards to best practice in diagnosis, treatment, and service provision. Current best practise would support the use of history, examination and electro-diagnostic studies.

Dupuytren's Disease: Review of the Current Literature.

Dupuytren's disease is one of the most common condition seen by hand surgeons. It is not only prevalent but can also be a most debilitating condition resulting in significant loss of function of the fingers involved. The cause of this disease, however still remains largely unknown although some recent evidence suggests a stem cell etiology.

Thiocyanate and nitrite analysis using miniaturised isotachophoresis on a planar polymer chip.

A new method has been developed to improve the determination of thiocyanate using isotachophoresis. This method uses complexation with copper(II) as a mechanism for improving the separation of thiocyanate from chlorate and perchlorate. By using a pH of 3.

Strength of interactions between immobilized dye molecules and sol-gel matrices.

In this paper we present a new theory to re-examine the immobilization technique of dye doped sol-gel films, define the strength and types of possible bonds between the immobilized molecule and sol-gel glass, and show that the immobilized molecule is not free inside the pores as was previously thought. Immobilizing three different pH sensitive dyes with different size and functional groups inside the same sol-gel films revealed important information about the nature of the interaction between the doped molecule and the sol-gel matrix. The samples were characterized by means of ultraviolet-visible spectrophotometer (UV-VIS), thermal gravimetric analysis (TGA), mercury porosimetry (MP), nuclear magnetic resonance spectroscopy ((29)Si NMR) and field-emission environmental scanning electron microscopy (ESEM-FEG).

Determination of the potassium content of explosive residues using miniaturised isotachophoresis.

A new method has been developed to allow the determination of potassium in post-explosion residues to be made using miniaturised isotachophoresis. The method is based on the use of a caesium leading ion with 4.5 mM 18-crown-6 ether added to retard the potassium to allow reliable determinations to be made.

Optimisation of secondary electrospray ionisation (SESI) for the trace determination of gas-phase volatile organic compounds.

An electrospray ionisation triple quadrupole mass spectrometer (Varian 1200 L) was modified to accept nitrogen samples containing low concentrations of volatile organic compounds. Six candidate probe compounds, methyl decanoate, octan-3-one, 2-ethylhexanoic acid, 1,4-diaminobutane, dimethyl methylphosphonate, and 2,3-butanediol, at concentrations below 50 ppb(v) were generated with permeation tubes in a test atmosphere generator. The concept of using a set of molecular probes to evaluate gas-phase electrospray ionisation of volatile analytes was assessed and the feasibility of adopting a unified ionisation approach for gas and liquid contamination of exobiotic environments established.

A miniaturised isotachophoresis method for magnesium determination.

The use of malonic acid as a complexing agent has enabled a new method to be devised to allow the determination of magnesium to be made using miniaturised isotachophoresis. Using a leading electrolyte of 10 mmol L(-1) caesium hydroxide and 2 mmol L(-1) malonic acid at pH 5.1 gave the method a high specificity towards magnesium.

Label-free detection with the resonant mirror biosensor.

The resonant mirror (RM) biosensor is a leaky waveguide-based instrument that uses the evanescent field to probe changes in the refractive index at the sensing surface.The RM can therefore be used to monitor in real-time and label-free the interaction between an analyte in solution and its biospecific partner immobilized on the waveguide surface.The RM has been used in studying the interaction of a variety of moieties including proteins, carbohydrates, cells, nucleic acids and receptors, leading to applications in areas such as clinical diagnostics, homeland security, and pharmaceutical and biomolecular interactions.

Determination of chlorine containing species in explosive residues using chip-based isotachophoresis.

A new method has been developed to allow the determination of the chlorate, chloride and perchlorate anions in inorganic explosive residues to be made using isotachophoresis (ITP). To enable a good separation of these species to be achieved the method involves the use of two complexing agents. Indium(III) is used to allow the determination of chloride whilst using nitrate as the leading ion and alpha-cyclodextrin is used to allow the separation of chlorate and perchlorate.

Miniaturised isotachophoresis of DNA.

This paper presents the findings of a feasibility study investigating the behaviour of DNA under conditions of miniaturised isotachophoresis. An electrolyte system comprising a leading electrolyte of 5mM perchloric acid at pH 6.0 and a terminating electrolyte of 10mM gallic acid was devised and used to perform isotachophoresis of DNA containing samples on a miniaturised poly(methyl methacrylate) device.

Synovial sarcoma mimicking haemophilic pseudotumour.

This is a case of a 36-year-old gentleman with haemophilia A who was presented with an acute atraumatic soft tissue swelling in the right thigh. Open biopsy was performed with the resultant diagnosis of a synovial cell sarcoma. Although the clinical findings were nonspecific they could easily have been found in a bleeding haemophilic pseudotumour.