Imperial College London

Professor Tony Cass

Faculty of Natural SciencesDepartment of Chemistry

Professor of Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 5195t.cass

 
 
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Location

 

301KMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

266 results found

Lawrance D, Williamson C, Boutelle MG, Cass AEGet al., 2015, Development of a disposable bile acid biosensor for use in the management of cholestasis, ANALYTICAL METHODS, Vol: 7, Pages: 3714-3719, ISSN: 1759-9660

Journal article

Chumphukam O, Le TT, Piletsky S, Cass AEGet al., 2015, Generation of a pair of independently binding DNA aptamers in a single round of selection using proximity ligation, CHEMICAL COMMUNICATIONS, Vol: 51, Pages: 9050-9053, ISSN: 1359-7345

Journal article

Nabavi E, Singh M, Zhou Y, Gallina M, Zhao H, Ma D, Cass A, Hanna G, Elson DSet al., Preliminary studies of targeted NIR photothermal therapy of human oesophageal adenocarcinoma in mice using multifunctional GNRs, British Medical Laser Association Conference

Conference paper

Maniyam MN, Sjahrir F, Ibrahim AL, Cass AEGet al., 2014, Biodetoxification of cyanide-containing industrial wastewaters by Rhodococcus UKMP-5M, BIOLOGIA, Vol: 69, Pages: 1635-1643, ISSN: 0006-3088

Journal article

Moreira FTC, Sharma S, Dutra RAF, Noronha JPC, Cass AEG, Sales MGFet al., 2014, Detection of cardiac biomarker proteins using a disposable basedon a molecularly imprinted polymer grafted onto graphite, Microchim Acta

A low-cost disposable was developed for rapid detection of the protein biomarker myoglobin (Myo) as a model analyte. A screen printed electrode was modified with a molecularly imprinted material grafted on a graphite support and incorporated in a matrix composed of poly(vinyl chloride) and the plasticizer o-nitrophenyloctyl ether. The proteinimprinted material (PIM) was produced by growing a reticulated polymer around a protein template. This is followed by radical polymerization of 4-styrenesulfonic acid, 2- aminoethyl methacrylate hydrochloride, and ethylene glycol dimethacrylate. The polymeric layer was then covalently bound to the graphitic support, and Myo was added during the imprinting stage to act as a template. Non-imprinted control materials (CM) were also prepared by omitting the Myo template. Morphological and structural analysis of PIM and CM by FTIR, Raman, and SEM/EDC microscopies confirmed the modification of the graphite support. The analytical performance of the SPE was assessed by square wave voltammetry. The average limit of detection is 0.79 μg of Myo per mL, and the slope is −0.193±0.006 μA per decade. The SPECM cannot detect such low levels of Myo but gives a linearresponse at above 7.2 μg·mL−1, with a slope of −0.719±0.02 μA per decade. Interference studies with hemoglobin, bovine serum albumin, creatinine, and sodium chloride demonstrated good selectivity for Myo. The method was successfully applied to the determination of Myo urine and is conceived to be a promising tool for screening Myo in point-ofcare patients with ischemia.

Journal article

Le TT, Chumphukam O, Cass AEG, 2014, Determination of minimal sequence for binding of an aptamer. A comparison of truncation and hybridization inhibition methods, RSC ADVANCES, Vol: 4, Pages: 47227-47233, ISSN: 2046-2069

Journal article

Harris-Birtill D, Singh M, Zhou Y, Gallina ME, Cass T, Elson DSet al., 2014, Gold Nanorod Reshaping using a Continuous Wave Laser, CLEO: Applications and Technology, Publisher: Optical Society of America

Conference paper

Chumphukam O, Le TT, Cass AEG, 2014, High efficiency acetylcholinesterase immobilization on DNA aptamer modified surfaces, Molecules, Vol: 19, Pages: 4986-4996, ISSN: 1420-3049

We report here the in vitro selection of DNA aptamers for electric eel acetylcholinesterase (AChE). One selected aptamer sequence (R15/19) has a high affinity towards the enzyme (Kd = 157 ± 42 pM). Characterization of the aptamer showed its binding is not affected by low ionic strength (~20 mM), however significant reduction in affinity occurred at high ionic strength (~1.2 M). In addition, this aptamer does not inhibit the catalytic activity of AChE that we exploit through immobilization of the DNA on a streptavidin-coated surface. Subsequent immobilization of AChE by the aptamer results in a 4-fold higher catalytic activity when compared to adsorption directly on to plastic.

Journal article

Moreira FTC, Sharma S, Dutra RAF, Noronha JPC, Cass AEG, Sales MGFet al., 2014, Protein-responsive polymers for point-of care detection of cardiac biomarker, Sensors and Actuators B: Chemica

This work describes a novel use for the polymeric film, Poly (o-aminophenol) (PAP) that was made responsive to a specific protein. This was achieved through templated electropolymerization of aminophenol (AP) in the presence of protein. The procedure involved adsorbing protein on the electrode surface and thereafter electroploymerizing the aminophenol. Proteins embedded at the outer surface of the polymeric film were digested by proteinase K and then washed away thereby creating vacant sites. The capacity of the template film to specifically rebind protein was tested with Myoglobin (Myo), a cardiac biomarker for ischemia. The films acted as biomimetic artificial antibodies and were produced on a gold (Au) screen printed electrode (SPE), as a step towards disposable sensors to enable point-of-care applications.Raman spectroscopy was used to follow the surface modification of the Au-SPE. The ability of the material to rebind Myo was measured by electrochemical techniques, namely electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The devices displayed linear responses to Myo in EIS and SWV assays down to 4.0 μg/mL and 3.5 μg/mL, respectively, with detection limits of 1.5 and 0.8 μg/mL. Good selectivity was observed in the presence of troponin T (TnT) and creatine kinase (CKMB) in SWV assays, and accurate results were obtained in applications to spiked serum. The sensor described in this work is a potential tool for screening Myo in point-of-care due to the simplicity of fabrication, disposability, short time response, low cost, good sensitivity and selectivity.

Journal article

El-Laboudi A, Sharma S, Oliver N, Hussein T, Patel D, Johnston D, Cass Tet al., 2014, DEVELOPMENT OF A NOVEL MICROPROBE ARRAY CONTINUOUS GLUCOSE SENSOR FOR TYPE 1 DIABETES: INTERFERENCE STUDIES, DIABETES TECHNOLOGY & THERAPEUTICS, Vol: 16, Pages: A65-A66, ISSN: 1520-9156

Journal article

Salehi-Reyhani A, Sharma S, Burgin E, Barclay M, Cass A, Neil MAA, Ces O, Willison KR, Klug DR, Brown A, Novakova Met al., 2014, Scaling advantages and constraints in miniaturized capture assays for single cell protein analysis (vol 13, pg 2066, 2013), LAB ON A CHIP, Vol: 14, Pages: 3430-3430, ISSN: 1473-0197

Journal article

Le TT, Adamiak B, Benton DJ, Johnson CJ, Sharma S, Fenton R, McCauley JW, Iqbal M, Cass AEGet al., 2014, Aptamer-based biosensors for the rapid visual detection of flu viruses, CHEMICAL COMMUNICATIONS, Vol: 50, Pages: 15533-15536, ISSN: 1359-7345

RNA aptamers showing affinity and specificity for different strains of human influenza virus were assembled onto gold nanoparticles that subsequently formed a gold nanoshell (AuNS) around the viral envelope. These shells could be visualised by transmission electron microscopy (TEM). Changes in size and structure of the AuNS coated virus can be used to detect the viruses. We show that sedimentation with a low cost centrifuge and visual determination can detect 3 × 108 viral particles.

Journal article

Harris-Birtill D, Singh M, Zhou Y, Elena-Gallina M, Cass T, Elson Det al., 2014, Gold nanorod reshaping using a continuous wave laser

Gold nanorods for photothermal therapy are shown, using spectroscopy and electron microscopy, to reshape after irradiation with a 6W/cm2 continuous wave laser, affecting their absorption coefficient and thus their clinical efficacy. © 2014 OSA.

Conference paper

Harris-Birtill D, Singh M, Zhou Y, Elena-Gallina M, Cass T, Elson Det al., 2014, Gold Nanorod Reshaping using a Continuous Wave Laser

Gold nanorods for photothermal therapy are shown, using spectroscopy and electron microscopy, to reshape after irradiation with a 6W/cm2 continuous wave laser, affecting their absorption coefficient and thus their clinical efficacy. © 2014 OSA.

Conference paper

El- Laboudi A, Sharma S, Santhanam H, Cook A, Oliver N, Cass AEG, Johnston Det al., 2013, Development Of A Novel Microprobe Array Continuous Glucose Monitor: Pre­clinical Validation, EASD

Background and aim: Despite clinical benefits, continuous glucose monitoring (CGM) devices are invasive and can be uncomfortable, negatively affecting concordance and effectiveness. In addition, CGM sensor accuracy is suboptimal in the critical hypoglycaemic range. To overcome these challenges, a novel continuous glucose sensor has been developed based on microprobe technology. It consists of a small, wearable patch containing several microscopic projections (microprobes) that penetrate the stratum corneum to access interstitial fluid. Aim: Mechanical and functional validation of the sensor prior to in vivo clinical studies. Mechanical validation assesses the ability to penetrate the stratum corneum without mechanical failure, while functional validation assesses the current produced in response to changing glucose concentration and the effects of sterilisation and insertion. Materials and methods: Each array had 64 microprobes arranged 8x8. Microprobe height is 1000 μm and tip diameter is 15 μm. Insertion tests were performed ex vivo in full thickness human skin. An Instron compression system was used to press the device into skin using forces of 7, 10, 15, 20 and 25 Newton. Skin penetration was confirmed by applying methylene blue dye to visualize created micropores and by histological examination. Fracture tests were performed in vitro using the Instron system to exert axial pressure against a metal probe using forces of 50, 100, 200, 300 and 400 Newton. Microprobes were examined using scanning electron microscopy before and after testing to detect failure and measure height reduction. To assess transverse fracture force, transverse pressure was exerted against one row of 8 microprobes till they fractured. Functional evaluation tests were performed in vitro by measuring the current generated in response to changing glucose concentration before and after gamma ray radiation and ex vivo skin insertion. Results: Insertion tests (n=10) demonstrated successful p

Conference paper

Nallapan Maniyam M, Sjahrir F, Ibrahim AL, Cass AEGet al., 2013, Biodegradation of cyanide by Rhodococcus UKMP-5M, BIOLOGIA, Vol: 68, Pages: 177-185, ISSN: 0006-3088

Journal article

El-Laboudi A, Sharma S, Oliver N, Santhanam H, Carton J, Cass T, Johnston Det al., 2013, DEVELOPMENT OF A NOVEL MICROPROBE ARRAY CONTINUOUS GLUCOSE MONITOR: MECHANICAL CHARACTERIZATION, Advanced Technologies and Treatments for Diabetes, Publisher: Mary Ann Liebert, Inc., Publishers

Conference paper

Bellomo R, Lipcsey M, Calzavacca P, Haase M, Haase-Fielitz A, Licari E, Tee A, Cole L, Cass A, Finfer S, Gallagher M, Lee J, Lo S, McArthur C, McGuinness S, Myburgh J, Scheinkestel C, RENAL Study Investigators and ANZICS Clinical Trials Groupet al., 2013, Early acid-base and blood pressure effects of continuous renal replacement therapy intensity in patients with metabolic acidosis., Intensive Care Med, Vol: 39, Pages: 429-436

PURPOSE: In acute kidney injury patients, metabolic acidosis is common. Its severity, duration, and associated changes in mean arterial pressure (MAP) and vasopressor therapy may be affected by the intensity of continuous renal replacement therapy (CRRT). We aimed to compare key aspects of acidosis and MAP and vasopressor therapy in patients treated with two different CRRT intensities. METHODS: We studied a nested cohort of 115 patients from two tertiary intensive care units (ICUs) within a large multicenter randomized controlled trial treated with lower intensity (LI) or higher intensity (HI) CRRT. RESULTS: Levels of metabolic acidosis at randomization were similar [base excess (BE) of -8 ± 8 vs. -8 ± 7 mEq/l; p = 0.76]. Speed of BE correction did not differ between the two groups. However, the HI group had a greater increase in MAP from baseline to 24 h (7 ± 3 vs. 0 ± 3 mmHg; p < 0.01) and a greater decrease in norepinephrine dose (from 12.5 to 3.5 vs. 5 to 2.5 μg/min; p < 0.05). The correlation (r) coefficients between absolute change in MAP and norepinephrine (NE) dose versus change in BE were 0.05 and -0.37, respectively. CONCLUSIONS: Overall, LI and HI CRRT have similar acid-base effects in patients with acidosis. However, HI was associated with greater improvements in MAP and vasopressor requirements (clinical trial no. NCT00221013).

Journal article

Sparke C, Moon L, Green F, Mathew T, Cass A, Chadban S, Chapman J, Hoy W, McDonald Set al., 2013, Estimating the total incidence of kidney failure in Australia including individuals who are not treated by dialysis or transplantation., Am J Kidney Dis, Vol: 61, Pages: 413-419

BACKGROUND: To date, incidence data for kidney failure in Australia have been available for only those who start renal replacement therapy (RRT). Information about the total incidence of kidney failure, including non-RRT-treated cases, is important to help understand the burden of kidney failure in the community and the characteristics of patients who die without receiving treatment. STUDY DESIGN: Data linkage study of national observational data sets. SETTING & PARTICIPANTS: All incident treated cases recorded in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) probabilistically linked to incident untreated kidney failure cases derived from national death registration data for 2003-2007. PREDICTOR: Age, sex, and year. OUTCOMES: Kidney failure, a combination of incident RRT or death attributed to kidney failure (without RRT). MEASUREMENTS: Total incidence of kidney failure (treated and untreated) and treatment rates. RESULTS: There were 21,370 incident cases of kidney failure in 2003-2007. The incidence rate was 20.9/100,000 population (95% CI, 18.3-24.0) and was significantly higher among older people and males (26.1/100,000 population; 95% CI, 22.5-30.0) compared with females (17.0/100,000 population; 95% CI, 14.9-19.2). There were similars number of treated (10,949) and untreated (10,421) cases, but treatment rates were influenced highly by age. More than 90% of cases in all age groups between 5 and 60 years were treated, but this percentage decreased sharply for older people; only 4% of cases in persons 85 years or older were treated (ORs for no treatment of 115 [95% CI, 118-204] for men ≥80 years and 400 [95% CI, 301-531] for women ≥80 years compared with women who were <50 years). LIMITATIONS: Cross-sectional design, reliance on accurate coding of kidney failure in death registration data. CONCLUSIONS: Almost all Australians who develop kidney failure at younger than 60 years receive RRT, but treatment rates decrease substa

Journal article

Moreira FTC, Sharma S, Dutra RAF, Noronha JPC, Cass AEG, Sales MGFet al., 2013, Smart Plastic Antibody Material (SPAM) tailored on disposable screen printed electrodes for protein recognition: application to Myoglobin detection, Biosensors and Bioelectronics, Vol: 45, Pages: 237-244

This work introduces two major changes to the conventional protocol for designing plastic antibodies: (i) the imprinted sites were created with charged monomers while the surrounding environment was tailored using neutral material; (ii) and the protein was removed from its imprinted site by means a protease, aiming at preserving the polymeric network of the plastic antibody. To our knowledge, these approaches were never presented before and the resulting material was named here as smart plastic antibody material (SPAM).As proof of concept, SPAM was tailored on top of disposable gold-screen printed electrodes (Au-SPE), following a bottom-up approach, for targeting Myoglobin (Myo) in a point-of-care context. The existence of imprinted sites was checked by comparing a SPAM modified surface to a negative control, consisting of similar material where the template was omitted from the procedure and called non-imprinted materials (NIMs). All stages of the creation of the SPAM and NIM on the Au layer were followed by both electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). AFM imaging was also performed to characterize the topography of the surface.There are two major reasons supporting the fact that plastic antibodies were effectively designed by the above approach: (i) they were visualized for the first time by AFM, being only present in the SPAM network; (ii) and only SPAM material was able to rebind to the target protein and produce a linear electrical response against EIS and square wave voltammetry (SWV) assays, with NIMs showing a similar-to-random behaviour. The SPAM/Au-SPE devices displayed linear responses to Myo in EIS and SWV assays down to 3.5 μg/mL and 0.58 μg/mL, respectively, with detection limits of 1.5 and 0.28 µg/mL. SPAM materials also showed negligible interference from troponin T (TnT), bovine serum albumin (BSA) and urea under SWV assays, showing promising results for point-of-care applications when applied to spiked

Journal article

Le TT, Scott S, Cass AEG, 2013, Streptavidin binding bifunctional aptamers and their interaction with low molecular weight ligands, ANALYTICA CHIMICA ACTA, Vol: 761, Pages: 143-148, ISSN: 0003-2670

Journal article

Maniyam MN, Sjahrir F, Ibrahim AL, Cass AEGet al., 2013, Biodegradation of cyanide by acetonitrile-induced cells of Rhodococcus sp UKMP-5M, JOURNAL OF GENERAL AND APPLIED MICROBIOLOGY, Vol: 59, Pages: 393-404, ISSN: 0022-1260

Journal article

Finfer S, Wernerman J, Preiser J-C, Cass T, Desaive T, Hovorka R, Joseph JI, Kosiborod M, Krinsley J, Mackenzie I, Mesotten D, Schultz MJ, Scott MG, Slingerland R, Van den Berghe G, Van Herpe Tet al., 2013, Clinical review: Consensus recommendations on measurement of blood glucose and reporting glycemic control in critically ill adults, CRITICAL CARE, Vol: 17, ISSN: 1466-609X

Journal article

El-Laboudi A, Oliver NS, Cass A, Johnston Det al., 2013, Use of Microneedle Array Devices for Continuous Glucose Monitoring: A Review, DIABETES TECHNOLOGY & THERAPEUTICS, Vol: 15, Pages: 101-115, ISSN: 1520-9156

Journal article

Mie M, Kai T, Le T, Cass AEG, Kobatake Eet al., 2013, Selection of DNA Aptamers with Affinity for Pro-gastrin-Releasing Peptide (proGRP), a Tumor Marker for Small Cell Lung Cancer, APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY, Vol: 169, Pages: 250-255, ISSN: 0273-2289

Journal article

Salehi-Reyhani A, Sharma S, Burgin E, Barclay M, Cass AEG, Neil MEE, Ces O, Willison KR, Klug Det al., 2013, Scaling Advantages and Constraints in Miniaturized Capture Assays for Single Cell Protein Analysis, Lab on A Chip, Vol: 13, Pages: 2066-2074, ISSN: 1473-0197

Measuring protein expression in single cells is the basis of single cell proteomics. The sensitivity and dynamic range of a single cell immunoassay should ideally be such that proteins that are expressed between 1 – 106 copies per cell can be detected and counted. We have investigated the effect of miniaturizing antibody microarrays by reducing capture spot sizes from 100 μm to 15 μm using dip pen nanolithography. We demonstrate that protocols developed for printing and passivating antibody capture spots using conventional pin based contact printing can be directly transferred to dip-pen lithography whilst retaining the capture activity per unit area. Using a simple kinetic model, we highlight how the limit of detection and dynamic range of a sandwich immunoassay, respectively, increase and decrease when spot size is reduced. However, we show that reducing spot size is more effective than increasing assay chamber volume when seeking to multiplex such a microfluidic immunoassay. Although, we make particular reference to single cell microfluidic immunoassays, the topics discussed here are applicable to capture assays in general.

Journal article

Sharma S, Srisa-Art M, Scott S, Asthana A, Cass AEGet al., 2012, Droplet-Based Microfluidics, Publisher: Springer

Droplet-based microfluidics or digital microfluidics is a subclass of microfluidic devices, wherein dropletsare generated using active or passive methods. The active method for generation of droplets involves theuse of an external factor such as an electric field for droplet generation. Two techniques that fall in thiscategory are dielectrophoresis (DEP) and electrowetting on dielectric (EWOD). In passive methods, thedroplet generation depends on the geometry and dimensions of the device. T-junction and flow focusingmethods are examples of passive methods used for generation of droplets. In this chapter the methods usedfor droplet generation, mixing of contents of droplets, and the manipulation of droplets are described inbrief. A review of the applications of digital microfluidics with emphasis on the last decade is presented.

Book

Sharma S, Reyhani AS, Bahrami A, Intisar E, Santhanam H, Michelakis K, Cass AEGet al., 2012, A novel method for fabricating nanostructures via nanotemplates using dip pen nanolithography, Micro & Nano Letters, Vol: 7, Pages: 1038-1040

Dip-pen nanolithography (DPN) relies on the compatibility between the ink used and the substrate it is written on. This has lead to a significant reliance for DPN on thiol-gold chemistries for the fabrication of nanostructures. This reported work demonstrates a method for creating nanostructures through nanotemplates that allows a wider range of substrates and inks to be used. The substrate was spin-coated with a thin layer of polymer which is selectively removed using a scanning probe microscopy tip coated with a solvent. This produces nanotemplates that are subsequently used to create nanostructures by metallisation. Compared with directly written templates these nanotemplates facilitate longer interaction between inking material and the substrate. They also allow a controlled spatial resolution along the z-axis and eliminate the need for any blocking agents to prevent non-specific adsorption. This method allows DPN to be expanded to applications beyond thiol-gold chemistries.

Journal article

Maniyam MN, Sjahrir F, Ibrahim AL, Cass AEGet al., 2012, Cyanide degradation by immobilized cells of Rhodococcus UKMP-5M, BIOLOGIA, Vol: 67, Pages: 837-844, ISSN: 0006-3088

Journal article

Tian PY, de Jonge LT, Autefage H, Cass AE, Stevens MMet al., 2012, Engineered alkaline phosphatase with improved functionality immobilized on bone implant surfaces, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 6, Pages: 195-195, ISSN: 1932-6254

Journal article

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