Imperial College London

Professor Tony Cass

Faculty of Natural SciencesDepartment of Chemistry

Senior Research Investigator
 
 
 
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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

286 results found

Cass AEG, Zhang Y, 2011, Nucleic acid aptamers: ideal reagents for point-of-care diagnostics?, FARADAY DISCUSSIONS, Vol: 149, Pages: 49-61, ISSN: 1364-5498

Journal article

Trzebinski J, Sharma S, Moniz A-B, Michelakis K, Zhang Y, Cass AEGet al., 2011, Microfluidic device to investigate factors affecting performance in biosensors designed for transdermal applications, Lab On a Chip: microfluidic and nanotechnologies for chemistry, biology, and bioengineering, Vol: 12, Pages: 348-352

In this work we demonstrate a novel microfluidic based platform to investigate the performance of 3D out-of-plane microspike array based glucose and lactate biosensors. The microspike array was bonded with a glass slide and modified with glucose oxidase or lactate oxidase using covalent coupling chemistry. An epoxy-polyurethane based membrane was used to extend the linear working range (from 0 to 25mM of substrate) of these biosensors. Both lactate and glucose sensors performed well in the clinically relevant substrate concentration range. Glucose microspikes were further investigated with respect to the effects of substrate transfer by incorporation into a microfluidic system. Data from the microfluidic system revealed that the sensor response is mainly dependent on enzyme kinetics rather than membrane permeability to glucose. The robustness of the sensors was demonstrated by its consistency in performance extending over 48 hours.

Journal article

Trzebinski J, Moniz A-B, Sharma S, Burugapalli K, Moussy F, Cass AEGet al., 2011, Hydrogel Membrane Improves Batch-to-Batch Reproducibility of an Enzymatic Glucose Biosensor, Electroanalysis

A permselective membrane is a critical component that defines the linear detection limits, the sensitivity, and thus the ultimate efficacy of an enzymatic biosensor. Although membranes like epoxy-polyurethane (epoxy-PU) and Nafion are widely used and provide the desired glucose detection limits of 2 to 30 mM, both the within batch and batch-to-batch variability of sensors that use these materials is a concern. The hypothesis for this study was that a crosslinked hydrogel would have a sufficiently uniform porosity and hydrophilicity to address the variability in sensor sensitivity. The hydrogel was prepared by crosslinking di-hydroxyethyl methacrylate, hydroxyethyl methacrylateand N-vinyl pyrrolidone with 2.5 mol% ethylene glycol dimethacrylate using water soluble initiators – ammonium persulfate and sodium metabisulfite under a nitrogen atmosphere. The hydrogel was applied to the sensor bydip coating during polymerisation. Electrochemical measurements revealed that the response characteristics of sensors coated with this membrane are highly consistent. Scanning electrochemical microscopy (SECM) was used tospatially resolve glucose diffusion through the membrane by measuring the consequent H2O2 release and compared with an epoxy-PU membrane. Hydrogen peroxide measurements using SECM revealed that the epoxy-PU membranes had uneven lateral diffusion profiles compared to the uniform profile of the hydrogel membranes. Theuneven diffusion profiles of epoxy-PU membranes are attributed to a fabrication method that results in uneven membrane properties, while the uniform diffusion profiles of the hydrogel membranes are primarily dictated by their uniform pore size.

Journal article

Le TT, Wilde CP, Grossman N, Cass AEGet al., 2011, A simple method for controlled immobilization of proteins on modified SAMs, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 5271-5278, ISSN: 1463-9076

Journal article

Yue X, Drakakis EM, Mantalaris A, Cass AEGet al., 2010, Generation of spatio-temporal concentration profiles for cell culture systems: A case study in ammonia, Measurement, Vol: 43, Pages: 1207-1216, ISSN: 0263-2241

Journal article

Techanukul T, Pereira F, Lipka A, Line JS, Wood SL, Lewis P, Hassard S, Cass AEG, Nagy JMet al., 2010, CE-based sample quality assessment prior to 2-D gel electrophoresis: Towards the standardization of gel-based proteomics, JOURNAL OF SEPARATION SCIENCE, Vol: 33, Pages: 2536-2546, ISSN: 1615-9306

Journal article

Jun M, Foote C, Lv J, Neal B, Patel A, Nicholls SJ, Grobbee DE, Cass A, Chalmers J, Perkovic Vet al., 2010, Effects of fibrates on cardiovascular outcomes: a systematic review and meta-analysis, LANCET, Vol: 375, Pages: 1875-1884, ISSN: 0140-6736

Journal article

Cass T, 2010, MOLECULES TO DEVICES <i>The Role of Engineering in Next Generation Point of Care Tests</i>, 3rd International Conference on Health Informatics (HEALTHINF 2010), Publisher: INSTICC-INST SYST TECHNOLOGIES INFORMATION CONTROL & COMMUNICATION, Pages: IS9-IS9

Conference paper

Zoungas S, Ninomiya T, Huxley R, Cass A, Jardine M, Gallagher M, Patel A, Vasheghani-Farahani A, Sadigh G, Perkovic Vet al., 2009, Systematic review: sodium bicarbonate treatment regimens for the prevention of contrast-induced nephropathy., Ann Intern Med, Vol: 151, Pages: 631-638

BACKGROUND: Intravenous sodium bicarbonate has been proposed to reduce the risk for contrast-induced nephropathy (CIN). PURPOSE: To determine the effect of sodium bicarbonate on the risk for CIN. DATA SOURCES: MEDLINE, PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials from 1950 to December 2008; conference proceedings; and ClinicalTrials.gov, without language restriction. STUDY SELECTION: Randomized, controlled trials of intravenous sodium bicarbonate that prespecified the outcome of CIN as a 25% increase in baseline serum creatinine level or an absolute increase of 44 micromol/L (0.5 mg/dL) after radiocontrast administration. DATA EXTRACTION: Using standardized protocols, 2 reviewers serially abstracted data for each study. DATA SYNTHESIS: 23 published and unpublished trials with information on 3563 patients and 396 CIN events were included. The pooled relative risk was 0.62 (95% CI, 0.45 to 0.86), with evidence of significant heterogeneity across studies (I(2) = 49.1%; P = 0.004). Some heterogeneity was due to the difference in the estimates between published and unpublished studies: relative risk, 0.43 (CI, 0.25 to 0.75) versus 0.78 (CI, 0.52 to 1.17), respectively. Meta-regression showed that small, poor-quality studies that assessed outcomes soon after radiocontrast administration were more likely to suggest benefit (P < 0.05 for all). No clear effects of treatment on the risk for dialysis, heart failure, and total mortality were identified. LIMITATION: Power to assess clinical end points was limited. CONCLUSION: The effectiveness of sodium bicarbonate treatment to prevent CIN in high-risk patients remains uncertain. Earlier reports probably overestimated the magnitude of any benefit, whereas larger, more recent trials have had neutral results. Large multicenter trials are required to clarify whether sodium bicarbonate has value for prevention of CIN before routine use can be recommended. PRIMARY FUNDING SOURCE: None.

Journal article

Nigwekar SU, Cass A, Gallagher MP, Jardine MJ, Kang A, Kulshrestha S, Navaneethan SD, Perkovic V, Strippoli GFM, Zoungas Set al., 2009, Interventions for lowering plasma homocysteine levels in dialysis patients, Cochrane Database of Systematic Reviews, ISSN: 1469-493X

Journal article

Peiris DP, Patel AA, Cass A, Howard MP, Tchan ML, Brady JP, De Vries J, Rickards BA, Yarnold DJ, Hayman NE, Brown ADet al., 2009, Cardiovascular disease risk management for Aboriginal and Torres Strait Islander peoples in primary health care settings: findings from the Kanyini Audit., Med J Aust, Vol: 191, Pages: 304-309, ISSN: 0025-729X

OBJECTIVE: To describe cardiovascular disease (CVD) risk management in Indigenous primary health care. DESIGN, SETTING AND PARTICIPANTS: Review of 1165 randomly selected case records of Indigenous Australian adults, aged >/= 18 years, regularly attending eight health services in diverse settings in New South Wales, Queensland and Central Australia, October 2007 - May 2008. MAIN OUTCOME MEASURE: Adherence to CVD risk screening and management guidelines, especially with respect to overall or absolute CVD risk. RESULTS: More than half the people in the sample (53%) were not adequately screened for CVD risk according to national recommendations. Underscreening was significantly associated with younger age, less frequent attendance, and lower uptake of the Medicare Health Assessment. Of the sample, 9% had established CVD, and 29% of those aged >/= 30 years were classified as high risk according to the 2004 National Heart Foundation of Australia (NHFA) adjusted Framingham equation. Of those with CVD, 40% (95% CI, 30%-50%) were not prescribed a combination of blood pressure (BP) medicines, statins and antiplatelet agents, and 56% (95% CI, 49%-62%) of high-risk individuals without CVD were not prescribed BP medicines and statins. For high-risk individuals not prescribed BP medicines or statins, 74% (95% CI, 64%-84%) and 30% (95% CI, 23%-39%) respectively, did not meet 2004 NHFA criteria for prescribing of these medications, and of those already prescribed BP medicines or statins, 41% (95% CI, 36%-47%) and 59% (95% CI, 52%-66%) did not meet respective guideline targets. CONCLUSIONS: These management gaps are similar to those found in non-Indigenous health care settings, suggesting deficiencies across the health system. Prescribing guidelines which exclude many high-risk individuals contribute to suboptimal management. Guideline reform and improved health service capacity could substantially improve Indigenous vascular health.

Journal article

Webster RJ, Heeley EL, Peiris DP, Bayram C, Cass A, Patel AAet al., 2009, Gaps in cardiovascular disease risk management in Australian general practice., Med J Aust, Vol: 191, Pages: 324-329, ISSN: 0025-729X

OBJECTIVE: To evaluate the management of cardiovascular disease (CVD) risk in Australian general practice. DESIGN, SETTING AND PARTICIPANTS: National cross-sectional survey of 99 Australian general practitioners participating in the Bettering the Evaluation and Care of Health (BEACH) program. Data on 2618 consecutive adult patients presenting to the participating GPs over a 5-week period from September to October 2006 were analysed. MAIN OUTCOME MEASURES: Proportions of patients screened, treated and reaching targets according to (1) current Australian CVD risk guidelines and (2) overall or absolute CVD risk. RESULTS: Blood pressure (BP) had not been recorded for 13% of the sample. Of 1400 patients not prescribed antihypertensive medication, treatment was indicated for 8%. Of 821 patients already prescribed antihypertensive medication, 59% were achieving target BPs. Data on low-density lipoprotein (LDL) cholesterol levels were not available for 53% of the 2175 patients who should have had lipid screening according to the guidelines. Of 624 patients not prescribed a statin, treatment was indicated for 41%. Of 368 already prescribed a statin, 62% were achieving target LDL cholesterol levels. Sufficient data for calculation of absolute risk had been recorded for 74% of the 1736 patients for whom such calculation was recommended by the guidelines. The remaining 26% either had at least one required variable unmeasured (20%) or missing from the data collection (6%). For those at high absolute CVD risk (without established disease) and those with established CVD, 23% and 53%, respectively, had been prescribed both antihypertensive medication and a statin. CONCLUSIONS: Gaps between guideline recommendations and practice in recording and managing BP were relatively low compared with gaps for lipids. When stratified by absolute risk, patients at high risk of a cardiovascular event were found to be substantially undertreated.

Journal article

Kang A, Nigwekar SU, Perkovic V, Kulshrestha S, Zoungas S, Navaneethan SD, Cass A, Gallagher MP, Ninomiya T, Strippoli GFM, Jardine MJet al., 2009, Interventions for lowering plasma homocysteine levels in kidney transplant recipients, Cochrane Database of Systematic Reviews, ISSN: 1469-493X

Journal article

Astuti Y, Topoglidis E, Cass AG, Durrant JRet al., 2009, Direct spectroelectrochemistry of peroxidases immobilised on mesoporous metal oxide electrodes: Towards reagentless hydrogen peroxide sensing, ANALYTICA CHIMICA ACTA, Vol: 648, Pages: 2-6, ISSN: 0003-2670

Journal article

Cass T, 2009, Bionanotechnology II: From Biomolecular Assembly to Applications, IDRUGS, Vol: 12, Pages: 163-164, ISSN: 1369-7056

Journal article

Oliver NS, Toumazou C, Cass AEG, Johnston DGet al., 2009, Glucose sensors: a review of current and emerging technology, DIABETIC MEDICINE, Vol: 26, Pages: 197-210, ISSN: 0742-3071

Journal article

Gielen F, deMello AJ, Cass T, Edel JBet al., 2009, Increasing the Trapping Efficiency of Particles in Microfluidic Planar Platforms by Means of Negative Dielectrophoresis, JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 113, Pages: 1493-1500, ISSN: 1520-6106

Journal article

Scott S, Cass AEG, Patel J, 2009, A microfluidic sensor platform for detection of pharmaceuticals in saliva using electrochemical detection, Pages: 320-322

This paper reports a microfluidic flow cell, housing an electrochemical sensor for the quantification of paracetamol in saliva. Saliva is an attractive matrix due to ease of sampling. We use double step chronocoulometry to record currents in a potential window with low intrinsic background in saliva with a limit of detection of 65μM. The prototype device consists of a PDMS microchannel bonded to glass substrate supporting planar 1.71mm2 Indium tin oxide (ITO) working electrode and electroplated Iridium oxide (Ir(O x)) pseudo-reference/counter electrode. Su-8 PDMS masters were laser ablation micromachined to form mixers allowing efficient on-chip sample preparation during sensor development. © 2009 CBMS.

Conference paper

Anderson K, Devitt J, Cunningham J, Preece C, Cass Aet al., 2008, "All they said was my kidneys were dead": Indigenous Australian patients' understanding of their chronic kidney disease., Med J Aust, Vol: 189, Pages: 499-503, ISSN: 0025-729X

OBJECTIVES: To explore the understanding of both Indigenous and non-Indigenous Australians with end-stage kidney disease (ESKD) about the cause of their disease, and how this understanding could affect patients' engagement with their treatment. DESIGN, SETTING AND PARTICIPANTS: Qualitative study conducted in 2005-2006 in nine hospital renal units and 17 associated dialysis centres in four states and the Northern Territory as part of the IMPAKT (Improving Access to Kidney Transplants) study. In-depth interviews were conducted with 146 Indigenous and 95 non-Indigenous Australians with ESKD, covering personal history of illness, social and psychosocial context, attitudes to treatments including transplantation, adequacy of information and communication, and satisfaction with services. RESULTS: Indigenous Australians were less certain about the cause of their illness and reported feeling uninformed but eager for information. They commonly reported lifestyle factors as potentially causal, with profound confusion about the role of alcohol. Indigenous Australians had considerable ambivalence towards biomedical explanations. CONCLUSIONS: Indigenous Australians are confused, frustrated and feel poorly informed about their illness. This study confirms the need to develop shared understandings about chronic kidney disease and to put in place the high-quality and appropriate educational resources that patients need.

Journal article

Winkle RF, Nagy JM, Cass AEG, Sharma Set al., 2008, Towards microfluidic technology-based MALDI-MS platforms for drug discovery: a review, EXPERT OPINION ON DRUG DISCOVERY, Vol: 3, Pages: 1281-1292, ISSN: 1746-0441

Journal article

Nagy J, Kang Y, Cass A, Mantalaris Aet al., 2008, Finding proteins in cell-conditioned media, Genetic Engineering and Biotechnology News, Vol: 28, ISSN: 1935-472X

Journal article

Pereira F, Hassard S, Cass A, Nagy JMet al., 2008, CZE of peptides using a multi-pixel detector array, Chimica Oggi, Vol: 26, Pages: 40-42, ISSN: 0392-839X

Capillary electrophoresis has been used in the analysis of peptides for decades, however traditional methods show excessive variability due to composition and sequence of the peptide, and variation in the interaction of the peptide with the separation medium. Multi-pixel detection along with the associated data analysis software improves reproducibility and sensitivity beyond current methods using UV absorption detection. The reproducibility of the data and the sensitivity of this 'no-label' multi-pixel detection approach are investigated using a mixture of known peptides. In the near future this will enable peptide mass finger printing based on the ability to assign molecular weight values to the peptides separated by charge.

Journal article

Pereira F, Hassard S, Cass A, Nagy JMet al., 2008, CZE of peptides using a multi-pixel detector array, CHIMICA OGGI-CHEMISTRY TODAY, Vol: 26, Pages: 40-42, ISSN: 0392-839X

Journal article

Lim M, Ye H, Drakakis EM, Yue X, Cass AEG, Panoskaltsis N, Mantalaris Aet al., 2008, Towards information-rich bioprocessing: Generation of spatio-temporal profiles through the use of design of experiments to determine optimal number and location of sensors - An example in thermal profiles, Biochemical Engineering Journal, Vol: 40, Pages: 1-7, ISSN: 1369-703X

Journal article

New SEP, Chester AH, Sharma S, Safinia L, Cass AEG, Schaffer MSP, Yacoub MH, Taylor PMet al., 2008, The effect of carbon nanotubes on mesenchymal stem cells in a 3D environment, Annual Tissue-Engineering-and-Regenerative-Medicine-International-Society-European-Chapter Meeting, Publisher: MARY ANN LIEBERT INC, Pages: 912-912, ISSN: 1937-3341

Conference paper

White SL, Chadban SJ, Jan S, Chapman JR, Cass Aet al., 2008, How can we achieve global equity in provision of renal replacement therapy?, Bull World Health Organ, Vol: 86, Pages: 229-237

There is a significant emerging burden of chronic and end-stage kidney disease in low- and middle-income countries, driven by population ageing and the global epidemic of type 2 diabetes. Sufferers of end-stage kidney disease require ongoing dialysis or kidney transplantation to survive; however, in many low- and middle-income countries, treatment options are strictly limited or unaffordable. Low numbers of maintenance dialysis patients and transplant recipients reflect profound economic and service provision challenges for health-care systems in low- and middle-income countries in sustaining renal replacement therapy programmes. Underdeveloped organ donor and transplant programmes, health system and financing issues, ethical regulation of transplantation and the cost of pharmaceuticals commonly pose additional barriers to the delivery of efficient and cost-effective renal replacement therapy. Development of locally appropriate transplant programmes, effective use of nongovernmental sources of funding, service planning and cost containment, use of generic drugs and local manufacture of dialysis consumables have the potential to make life-saving renal replacement therapy available to many more in need. Select low- and middle-income countries demonstrate more equitable provision of renal replacement therapy is possible outside high-income countries. For other low- and middle-income countries, education, the development of good public policy and a supportive international environment are critical. Prevention of end-stage kidney disease, ideally as part of an integrated approach to chronic vascular diseases, must also be a key objective.

Journal article

Patel BA, Arundell M, Quek RGW, Harvey SLR, Ellis IR, Florence MM, Cass AEG, Schor AM, O'Hare Det al., 2008, Individually addressable microelectrode array for monitoring oxygen and nitric oxide release, ANALYTICAL AND BIOANALYTICAL CHEMISTRY, Vol: 390, Pages: 1379-1387, ISSN: 1618-2642

Journal article

Johnson CJ, Zhukovsky N, Cass AEG, Nagy JMet al., 2008, Proteomics, nanotechnology and molecular diagnostics, PROTEOMICS, Vol: 8, Pages: 715-730, ISSN: 1615-9853

Journal article

Cass T, 2008, Biosensors, Advances in Tissue Engineering, Pages: 373-399, ISBN: 9781848161825

Increasingly biological sciences are being built on a quantitative foundation, based upon our ability to accurately determine the temporal and spatial variations in the concentration of key molecules. It is this quantitative analytical data that provides the testable basis for building hypotheses about biological systems. Although many, diverse analytical techniques have been used to collect quantitative data these are often destructive of the system being analysed. Biosensors by contrast promise the ability to measure selected molecules continuously and in real-time with good spatial resolution. They use specific molecular recognition at the surface of a transducer such that an electrical signal is generated in proportion to the concentration of the target analyte. Many different molecular recognition reagents have been exploited in this respect and include enzymes, binding proteins and nucleic acids, whilst electrochemical, optical and mass sensitive signal transduction devices have been used to generate the electrical signal (typically a voltage or current). Using biosensors in vivo presents additional challenges over and above simply relating signal to concentration. Biocompatibility is an ever-present issue and includes both the effect of the biological matrix on the sensor as well as sensor components on the biology. In this chapter a review of the different sensing modes is presented and their potential applicability to the monitoring of cells, tissue and tissue constructs is presented.

Book chapter

Yue X, Drakakis EM, Lim M, Radomska A, Ye H, Mantalaris A, Panoskaltsis N, Cass Aet al., 2008, A Real-Time Multi-Channel Monitoring System for Stem Cell Culture Process, IEEE Transactions on Biomedical Circuits and Systems, Vol: 2, Pages: 66-77, ISSN: 1932-4545

Journal article

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