Professor Roger Webb

A new protocol using time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been developed to identify the deposition order of a fingerprint overlapping an ink line on paper. By taking line scans of fragment ions characteristic of the ink molecules (m/z 358.2 and 372.2) where the fingerprint and ink overlap and by calculating the normalised standard deviation of the intensity variation across the line scan, it is possible to determine whether or not a fingerprint is above ink on a paper substrate. The protocol adopted works for a selection of fingerprints from four donors tested here and for a fingerprint that was aged for six months; for one donor, the very faint fingerprints could not be visualized using either standard procedures (ninhydrin development) or SIMS and therefore the protocol correctly gives an inconclusive result.

BACKGROUND: Paper spray mass spectrometry6 is a technique
that has recently emerged and has shown excellent
analytical sensitivity to a number of drugs in blood. As an
alternative to blood, fingerprints have been shown to
provide a noninvasive and traceable sampling matrix.
Our goal was to validate the use of fingerprint samples to
detect cocaine use.

METHODS: Samples were collected on triangular pieces
(168 mm2) of washed Whatman Grade I chromatography
paper. Following application of internal standard,
spray solvent and a voltage were applied to the paper
before mass spectrometry detection. A fingerprint visualization
step was incorporated into the analysis procedure
by addition of silver nitrate solution and exposing the
sample to ultraviolet light.

RESULTS: Limits of detection for cocaine, benzoylecgonine,
and methylecgonine were 1, 2, and 31 ng/mL respectively,
with relative standard deviations of less than 33%. No
matrix effects were observed. Analysis of 239 fingerprint
samples yielded a 99% true-positive rate and a 2.5%
false-positive rate, based on the detection of cocaine,
benzoylecgonine, or methylecgonine with use of a single
fingerprint.

CONCLUSIONS: The method offers a qualitative and noninvasive
screening test for cocaine use. The analysis
method developed is rapid (4 min/sample) and requires
no sample preparation.

BACKGROUND:

Recent publications have explored the
possibility of using fingerprints to confirm drug use, but
none has yet dealt with environmental contamination
from fingertips. Here we explored the possibility of establishing
an environmental cutoff for drug testing from
a single fingerprint.

METHODS:

Fingerprint samples (n=100) were collected
from the hands of 50 nondrug users before and after
handwashing to establish separate environmental cutoff
values and testing protocols for cocaine, benzoylecgonine,
heroin, and 6-monoacetylmorphine. The cutoff was challenged
by testing the fingerprints of drug-free volunteers
after shaking hands with drug users. Fingerprints from patients
who testified to taking cocaine (n = 32) and heroin
(n = 24) were also collected and analyzed.

RESULTS:

A different cutoff value needed to be applied,
depending on whether the fingerprints were collected as
presented or after handwashing. Applying these cutoffs gave
a 0%false-positive rate from the drug-free volunteers. After
application of the cutoff, the detection rate (compared to
patient testimony) for washed hands of patients was 87.5%
for cocaine use and 100% for heroin use.

CONCLUSIONS:

Fingerprints show enhanced levels of cocaine,
heroin, and their respective metabolites in patients
who testified to taking the substances, compared with the
population of na1¨ve drug users surveyed, and a cutoff
(decision level) can be established. The cutoff is robust
enough to account for small increases in analyte observed
after secondary transfer.

Ion beam analysis comprises of a group of analytical techniques tackling the elemental composition of thin films by probing them with MeV ions. These techniques exploit information from photons and particles that come from the interaction of the MeV ions with the sample surface. Secondary ions, yet another species ensuing from such interactions can also be analysed providing information on molecular composition. The only ion beam analysis technique addressing the molecular composition is MeV SIMS, enabling detection and imaging of organic matter. The molecular detection and imaging of organic material is dominated by other surface sensitive techniques, such as TOF SIMS, providing a strong competition to MeV SIMS. In a pursuit to fully exploit the advantages of MeV SIMS in the field, the possibility to extract MeV ions into the air can also be utilised, thus offering the potential for application of ambient based MeV SIMS.
In this work, a fully ambient MeV SIMS setup is introduced and commissioned at the University of Surrey Ion Beam Centre, and termed ?Ambient Pressure MeV SIMS?. The aims of this thesis are to optimise AP MeV SIMS for detection and imaging of organic species, as well as to explore potential applications for the technique. The complex optimisation of AP MeV SIMS described in this work encounters many parameters influencing either the electronic sputtering or gas dynamic of secondary ions. A great volume of the optimisation process has addressed the issue of an immense background contribution by investigation of its identity and origin. Moreover, the atmosphere encompassing the sampling area was investigated and the effect of different angles and types of a sheath gas directing the sample was tested.
The following work of this thesis demonstrates the application assessment of AP MeV SIMS. Here results of analysis of amino acids, explosives and synthetic organic pigments are presented. Finally, a description of a feasibility study on merging of AP MeV SIMS and HIPIXE with a purpose of simultaneous molecular and elemental imaging under ambient conditions is given.

Direct analyte-probed nano-extraction (DAPNe) is a method of extracting material from a microscale region of a sample and provides the opportunity for detailed mass spectrometry analysis of extracted analytes from a small area. The technique has been shown to provide enhanced sensitivity compared with bulk analysis by selectively removing analytes from their matrix and has been applied for selective analysis of single cells and even single organelles. However, the quantitative capabilities of the technique are yet to be fully evaluated. In this study, various normalisation techniques were investigated in order to improve the quantitative capabilities of the technique. Two methods of internal standard incorporation were applied to test substrates, which were designed to replicate biological sample matrices. Additionally, normalisation to the extraction spot area and matrix compounds were investigated for suitability in situations when an internal standard is not available. The variability observed can be significantly reduced by using a sprayed internal standard, and in some cases, by normalising to the extracted area.

This thesis investigates the possibility of using ambient ionisation and surface mass spectrometry for the detection and quantification of drugs of abuse in latent fingerprints. The use of fingerprints for drug testing in lieu of blood, oral fluid or urine reduces the biological hazard associated with these types of samples. The sample collection procedure is non-invasive, can be monitored to prevent cheating (submitting samples from a drug free individual) and the identity of the donor is embedded in the fingerprint ridge detail. In this thesis, three techniques ? desorption electrospray ionisation (DESI), liquid extraction surface analysis (LESA) and paper spray mass spectrometry, were evaluated for their ability to provide a rapid drug test from a fingerprint.
Paper spray-mass spectrometry was chosen for further development due to the ease of set-up, rapid nature of the analysis and potential to provide quantitative results. The final optimised method included full scan mass spectrometry measurements (quantitative) followed by tandem mass spectrometry (MS/MS) scans (qualitative) for the detection of cocaine, benzoylecgonine (BZE) and ecgonine methyl ester (EME). Limits of detection (LOD) were calculated to be 1 ng/mL, 2 ng/mL and 31 ng/mL for cocaine, BZE and EME, respectively.
Using the optimised method of analysis, 159 individual fingerprint samples (collected from individuals seeking treatment for substance abuse) were analysed with a 99% true positive rate through the detection of either cocaine, BZE or EME. The detection of these substances was corroborated by a positive oral fluid result from samples collected from the same individuals. Analysis of fingerprint samples collected from the non-drug users (n=80) indicated The significance of detecting the parent drug or metabolite in fingerprint samples was determined through the analysis of samples after contact with seized cocaine from Forensic Science Ireland. Cocaine, BZE and EME were found in fingerprints produced by contact, showing that the presence of a cocaine metabolite in a fingerprint is not enough to show that a suspect has taken a drug. Furthermore, secondary transfer scenarios showed that cocaine could be transferred through handshakes. None of the hand cleaning methods employed in this research were sufficient to remove all traces of cocaine from contact residues.
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Finally, the possibility of visualising the fingerprint ridge detail prior to analysis was tested and the presence of the analytes was qualitatively confirmed in fingerprint samples after application of silver nitrate. This is an important step that allows for sample traceability, whilst still providing high throughput analysis and sensitivity.

One of the greatest challenges in silicon photonics has been to induce light emission in silicon, with the ultimate vision is to have fully silicon-based photonics emitters or lasers which can operate by both optical and electrical pumping.

Comprehensive photoluminescence (PL) and electroluminescence (EL) studies are conducted on dislocation engineering light emitting diode structures based on silicon implanted (Si:B) with Ce, Eu, and Yb rare-earth (RE) ions. The PL and EL results show very bright luminescence intensity and dramatic red shifting in luminescence peaks which shows a possible novel phenomenon of RE energy transition modification. The modification is attributed to the direct transition from Si conduction band edge to RE manifolds? (_^2)F?_(7/2)^ , ?(_^2)F?_(5/2)^ for ?Ce?^(3+), ?(_^7)F?_j^ (j=0 to 4) for ?Eu?^(3+), ?(_^2)F?_(5/2)^ and ?(_^2)F?_(7/2)^ for ?Yb?^(3+).

The emissions are shifted from the conventional lowest internal energy transition in ?Ce?^(3+) from around blue spectrum at ~350 nm (due to (_^2)D_(3/2)^ excited state to the ?(_^2)F?_(7/2)^ , ?(_^2)F?_(5/2)^ transitions) to ~1.35 µm in Si:B&Ce. For ?Eu?^(3+) the emission is shifted from around the red spectrum at ~600 nm (due to (_^5)D_0^ excited state to the ?(_^7)F?_j^ transitions, j=0 to 4) to ~ 1.40 µm in Si:B&Eu and for ?Yb?^(3+) is shifted from slightly beyond the visible region at ~980 nm (due to ?(_^2)F?_(5/2)^ excited state to the ?(_^2)F?_(7/2)^ transition) to ~ 1.43 µm in Si:B&Yb samples. The new shifting of luminescence peak into NIR region is very important for optical communication in making LEDs and lasers.

Glioblastoma is an aggressive brain cancer with a median survival rate of 14.6 months post diagnosis. Treatments for glioblastoma include surgery, radiotherapy, and chemotherapy with the alkylating agent temozolomide (TMZ). In 50% of patients, TMZ treatment is ineffective due to the reparative action of the protein O6- MeG DNA methyltransferase (MGMT). The base excision repair (BER) pathway repairs the most common lesions caused by TMZ.

This work reports the characterization of several glioblastoma cell lines in terms of their repair status and sensitivity to traditional therapy of X-ray irradiation and TMZ. We find that the expression of BER proteins differed between cell lines, with alkyladenine-DNA-glycosylase (AAG) showing the greatest variation in expression. Sensitivity to TMZ and X-rays was MGMT dependent. Moreover, our results suggest that cell lines expressing higher AAG levels display increased sensitivity to X-rays and TMZ combination treatment in an MGMT independent fashion.

Pharmacological inhibition of BER enzymes AP-endonuclease (APE) and polymerase b (PolB) was examined, intending to enhance sensitivity of the glioblastoma cell lines to TMZ and X-ray or proton treatment. Methoxyamine (MX), an inhibitor of AP-endonuclease (APE) activity, leads to a modest increase in TMZ sensitivity. The combination of X-rays, MX and TMZ sensitised MGMT-negative cell lines, this was not seen in proton radiation. PolB inhibition greatly increased TMZ toxicity in conjunction with radiation in glioblastoma cell lines.

Proton irradiation systems were analysed and developed within this work, leading to a high-throughput broadbeam irradiation system. These methodologies lead to differences being detected in response to proton irradiation depending on the method used. This might in future, lead to further understanding of low-dose hypersensitivity.

In conclusion, the modulation of BER can enhance glioblastoma sensitivity to current treatment modalities, however, this is in an MGMT dependent fashion. These studies could provide insight for current clinical trials.

An increased rate of cellular proliferation is a hallmark of cancer cells and may be accompanied by an increase in ribosome biogenesis and dysregulation in rRNA synthesis. In this regard CX-5461 has been developed as a novel RNA polymerase I inhibitor and is currently in Phase I/II clinical trials. The work described herein sets out to explore the use of this agent in combination with radiation therapy in solid cancer cell lines to understand the associated molecular mechanisms using this approach. Previous work has examined the CX-5461 in haematological malignancies and some solid cancers. Reports have shown that, treatment with CX-5461 induces potent anti-proliferative effects alongside induction of apoptosis in haematological malignancies.
A panel of solid human tumour cell lines treated with CX-5461 indicated a broad spectrum of sensitivity (MTS Assay) with IC50 values ranging from 35nM to 1¼M. The mode of cell death following CX-5461 exposure in the cancer cell lines studied was cell context dependent- either via autophagy (LC3I ® LC3II conversion alongside p62 sequestosome decrease) or via apoptosis (AnnexinV staining and late PARP cleavage). Treatment with CX-5461 also induced marked levels of DNA damage as detected through increased gH2AX foci staining. The presence of senescence marker ²-galactosidase in CX-5461 treated cells indicates cell cycle arrest alongside the potent anti-proliferative effects of CX-5461 being highlighted through the clonogenic assays and decreased Ki-67 expression (flow cytometry).
Through combination experiments involving CX-5461 and X-ray radiotherapy the current study has identified the highest levels of increased effectiveness in interactions between CX- 5461 and X-rays within the CaSki cervical cancer cell line. Highly significant effects were seen when low dose radiation and low dose CX-5461 were used together (combination index CI -