Nanomaterials for pregnancy detection
File(s)
Author(s)
Albilal, Nawal
Type
Thesis
Abstract
Point of care (POC) is a powerful tool as a diagnostic test because of its advantage of
being small, portable device and rapid results obtained. One major class of POC is
the lateral flow assay (LFA), which is widely used for protein determinations. A
home pregnancy test is the most successful example of the LFAs. A limitation of
being quantitative or at best semi quantitative assay leads to improve the assay
performance and to enhance its sensitivity. Hence, for this project, a switch from
visual detections to electrochemical measurements is the primary goal, which
occurred by developing the assay’ concept with keeping the ease and robustness of
the traditional LF assay. The integration of streptavidin lateral flow with
electrochemical measurements (in particular voltammetric techniques) is the key
element to introduce an electrochemical lateral flow assay (ELFA). This concept was
based on the amplification of the polymer nanoparticles. A pH responsive eudragit S-
100 was synthesized by nanoprecipitation process. These PNPs are encapsulated with
redox active probe such as hydroxylmethyl ferrocene. Eudragit S-100 is dissolved at
pH > 7 and it is insoluble in an acidic condition. This dissolution mechanism is
preferable since the release of entrapped probe can be controlled until it is being
detectable at the test line. Our findings summarized as follows; nanoprecipitation
process is able to synthesis PNPs encapsulated both hydroxylmethyl ferrocene and
methylene blue. These small-sized particles (~200 nm and ~300 nm) have a highly
value negative zeta potentials (-34 mV and -29 mV). These two proprieties
respectively, are important in enhancing the probe loading efficiency and in efficient
adsorption with the antibody. From our data, it was found that more than 50% of the
probes were encapsulated. Further characterizations were performed to investigate
the probes’ electroactivity as well as their electrochemical behavior. These
voltammetric techniques include cyclic voltammetry and square wave voltammetry,
the results suggested good electrochemical behaviors of both probes in respect of
their release form the PNPs in immobilized format as well as in the aqueous phase.
Importantly, an electrochemical lateral flow assay (ELFA) was investigated the
FcMeOH-PNPs and was successfully demonstrated in the presence of varied
concentrations of hCG compared to the control (absence of hCG). This indicates that
the applied approach was proven. However, further improvements are needed. This
led to move toward the screen-printed technology to realize a point of care device.
being small, portable device and rapid results obtained. One major class of POC is
the lateral flow assay (LFA), which is widely used for protein determinations. A
home pregnancy test is the most successful example of the LFAs. A limitation of
being quantitative or at best semi quantitative assay leads to improve the assay
performance and to enhance its sensitivity. Hence, for this project, a switch from
visual detections to electrochemical measurements is the primary goal, which
occurred by developing the assay’ concept with keeping the ease and robustness of
the traditional LF assay. The integration of streptavidin lateral flow with
electrochemical measurements (in particular voltammetric techniques) is the key
element to introduce an electrochemical lateral flow assay (ELFA). This concept was
based on the amplification of the polymer nanoparticles. A pH responsive eudragit S-
100 was synthesized by nanoprecipitation process. These PNPs are encapsulated with
redox active probe such as hydroxylmethyl ferrocene. Eudragit S-100 is dissolved at
pH > 7 and it is insoluble in an acidic condition. This dissolution mechanism is
preferable since the release of entrapped probe can be controlled until it is being
detectable at the test line. Our findings summarized as follows; nanoprecipitation
process is able to synthesis PNPs encapsulated both hydroxylmethyl ferrocene and
methylene blue. These small-sized particles (~200 nm and ~300 nm) have a highly
value negative zeta potentials (-34 mV and -29 mV). These two proprieties
respectively, are important in enhancing the probe loading efficiency and in efficient
adsorption with the antibody. From our data, it was found that more than 50% of the
probes were encapsulated. Further characterizations were performed to investigate
the probes’ electroactivity as well as their electrochemical behavior. These
voltammetric techniques include cyclic voltammetry and square wave voltammetry,
the results suggested good electrochemical behaviors of both probes in respect of
their release form the PNPs in immobilized format as well as in the aqueous phase.
Importantly, an electrochemical lateral flow assay (ELFA) was investigated the
FcMeOH-PNPs and was successfully demonstrated in the presence of varied
concentrations of hCG compared to the control (absence of hCG). This indicates that
the applied approach was proven. However, further improvements are needed. This
led to move toward the screen-printed technology to realize a point of care device.
Version
Open Access
Date Issued
2014-10
Date Awarded
2016-08
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Cass, Tony
Williamson, Catherine
Sponsor
King khalid foundation
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)