5 research outputs found
Detection of prostate cancer biomarker using molecularly imprinted polymers
Successful treatment of prostate cancer (PCa) depends on early diagnosis and
screening, which currently relies on the measurement of serum prostate specific
antigen (PSA) levels. The overarching aim of the project was to generate
molecularly imprinted polymers for PCa biomarkers, with subsequent integration
with a sensing platform to allow for rapid, point of care detection and monitoring.
The initial work involved the use of simple PSA epitopes for epitope imprinting
using conventional imprinting techniques. A four amino acid sequence from the Cterminus
of PSA was imprinted with MAA, Aam and Urea monomers to obtain bulk
imprinted polymers. Apparent Kd of 102 μM, 154 μM, 194 μM was obtained for
MAA, AAm, Urea based bulk mini-MIPs respectively. Epitope imprinting was
further developed using a surface imprinting approach, via electropolymersiation of
dopamine to detect an epitopic sequence from pro-PSA. An improvement in Kd from
bulk-imprinted polymers, with an apparent Kd of 2.9 μM was obtained with the
surface electrochemical MIP sensor. However, both epitope imprinting technique
lacked sensitivity to measure clinical relevant concentrations of PSA (nM range). As
a consequence, a more sophisticated technique called hybrid imprinting was
developed to build an electrochemical MIP sensor. Hybrid MIP imprinting utilised
an aptamer with established affinity towards PSA to trap the aptamer-PSA complex
into a surface grown electropolymer (polydopamine). The resulting aptamer lined
polymer pockets exhibited high selectivity and affinity towards PSA (apparent Kd
0.3 nM). The apta-MIP sensor was also able to discriminate from a homologous
protein (human Kallikrein 2) and was resilient to fouling from serum proteins. The
apta-MIP sensor was further translated to a MOSFET device whereby successful
detection of PSA at clinically relevant concentration was obtained in human plasma.
Although good sensitivity and selectivity was obtained with the hybrid-MIP sensors,
further research is required to understand the binding mechanism of the template to
the MIP
Aptamer-MIP hybrid receptor for highly sensitive electrochemical detection of prostate specific antigen
This study reports the design and evaluation of a new synthetic receptor sensor based on the amalgamation of biomolecular recognition elements and molecular imprinting to overcome some of the challenges faced by conventional protein imprinting. A thiolated DNA aptamer with established affinity for prostate specific antigen (PSA) was complexed with PSA prior to being immobilised on the surface of a gold electrode. Controlled electropolymerisation of dopamine around the complex served to both entrap the complex, holding the aptamer in, or near to, it’s binding conformation, and to localise the PSA binding sites at the sensor surface. Following removal of PSA, it was proposed that the molecularly imprinted polymer (MIP) cavity would act synergistically with the embedded aptamer to form a hybrid receptor (apta-MIP), displaying recognition properties superior to that of aptamer alone. Electrochemical impedance spectroscopy (EIS) was used to evaluate subsequent rebinding of PSA to the apta-MIP surface. The apta-MIP sensor showed high sensitivity with a linear response from 100 pg/ml to 100 ng/ml of PSA and a limit of detection of 1 pg/ml, which was three-fold higher than aptamer alone sensor for PSA. Furthermore, the sensor demonstrated low cross-reactivity with a homologous protein (human Kallikrein 2) and low response to human serum albumin (HSA), suggesting possible resilience to the non-specific binding of serum proteins
Hybrid Synthetic Receptors on MOSFET Devices for Detection of Prostate Specific Antigen in Human Plasma
The study reports the use of extended gate field-effect transistors (FET) for the label-free and sensitive detection of prostate cancer (PCa) biomarkers in human plasma. The approach integrates for the first time hybrid synthetic receptors comprising of highly selective aptamer-lined pockets (apta-MIP) with FETs for sensitive detection of prostate specific antigen (PSA) at clinically relevant concentrations. The hybrid synthetic receptors were constructed by immobilizing an aptamer–PSA complex on gold and subjecting it to 13 cycles of dopamine electropolymerization. The polymerization resulted in the creation of highly selective polymeric cavities that retained the ability to recognize PSA post removal of the protein. The hybrid synthetic receptors were subsequently used in an extended gate FET setup for electrochemical detection of PSA. The sensor was reported to have a limit of detection of 0.1 pg/mL with a linear detection range from 0.1 pg/mL to 1 ng/mL PSA. Detection of 1–10 pg/mL PSA was also achieved in diluted human plasma. The present apta-MIP sensor developed in conjunction with FET devices demonstrates the potential for clinical application of synthetic hybrid receptors for the detection of clinically relevant biomarkers in complex samples
Aptamer-MIP hybrid receptor for highly sensitive electrochemical detection of prostate specific antigen
This study reports the design and evaluation of a new synthetic receptor sensor based on the amalgamation of biomolecular recognition elements and molecular imprinting to overcome some of the challenges faced by conventional protein imprinting. A thiolated DNA aptamer with established affinity for prostate specific antigen (PSA) was complexed with PSA prior to being immobilised on the surface of a gold electrode. Controlled electropolymerisation of dopamine around the complex served to both entrap the complex, holding the aptamer in, or near to, it’s binding conformation, and to localise the PSA binding sites at the sensor surface. Following removal of PSA, it was proposed that the molecularly imprinted polymer (MIP) cavity would act synergistically with the embedded aptamer to form a hybrid receptor (apta-MIP), displaying recognition properties superior to that of aptamer alone. Electrochemical impedance spectroscopy (EIS) was used to evaluate subsequent rebinding of PSA to the apta-MIP surface. The apta-MIP sensor showed high sensitivity with a linear response from 100 pg/ml to 100 ng/ml of PSA and a limit of detection of 1 pg/ml, which was three-fold higher than aptamer alone sensor for PSA. Furthermore, the sensor demonstrated low cross-reactivity with a homologous protein (human Kallikrein 2) and low response to human serum albumin (HSA), suggesting possible resilience to the non-specific binding of serum proteins