The development of a time-resolved confocal microscope for single molecule detection of luminescent polymers

This report details the construction and testing of a confocal microscope for use in single molecule fluorescence spectroscopy. With the prospect of making time-resolved lifetime and spectral measurements of π-conjugated polymers in the condensed phase, the system employs a pulsed 390nm, 65ps diode laser along with compact electronics for time-correlated single photon counting. Following optimisation the microscope records continuous photon arrival times with l00ps resolution, and fluorescence lifetime decays with 40ps resolution. Isolation of polymer chains has been investigated as a function of dilution by the dispersion of poly[9,9di(ethylhexyl)fluorene] (PF2/6) in a variety of host matrices. Films have been prepared by spin coating from toluene and the emission spectra, confocal lifetime and anisotropy have been investigated. Whilst the choice of host does not show any considerable influence on the spectral characteristics of the luminescent polymer, concentration and spin speed were observed to significantly influence the photophysical properties of the film. Spectral blue shifts in the emission band have been observed as the dilution of the luminescent polymer increases, reaching a maximum shift of 20nm in the most dilute samples. In line with the spectral shift, lifetime measurements show that the fluorescence decay becomes increasingly mono-exponential with dilution. In films exhibiting the maximum spectral blue shift, mono-exponential fluorescence decay was observed, for the oligomer oligo [9,9di(ethylhexyl)fluorene] (_N=20) (OF2/6) in zeonex the lifetime is found to be τ = 0.92ns. The dilution at which this occurs varies from 1x10(^-4) % w/w to 1x10(^-6) % w/w depending on spin speed and host matrix. Significantly longer that the lifetime of OF2/6 in solution, this is thought to be very close to the natural radiative lifetime of the polymer and is taken as a clear indication of chain isolation within the host matrix. Spectral blue shift and progression to mono-exponential fluorescence decay are explained in terms of the decline of low energy aggregate states and a reduction in non-radiative interchain energy transfer due to increased interchain separation. Confocal imaging using the specimen scanning technique has been developed using an electronically controlled x y piezo-stage. By optimising the optical set up the confocal image resolution is currently 0.369nm. The maximum theoretical confocal resolution at 390nm excitation is 0.268nm; the cause of this loss in resolution is thought to originate from slight non-uniformity in the excitation source

An evolutionary perspective of lifespan and epigenetic inheritance

In the last decade epigenetics has come to the fore as a discipline which is central to biogerontology. Age associated epigenetic changes are routinely linked with pathologies, including cardiovascular disease, cancer, and Alzheimer's disease; moreover, epigenetic clocks are capable of correlating biological age with chronological age in many species including humans. Recent intriguing empirical observations also suggest that inherited epigenetic effects could influence lifespan/longevity in a variety of organisms. If this is the case, an imperative exists to reconcile lifespan/longevity associated inherited epigenetic processes with the evolution of ageing. This review will critically evaluate inherited epigenetic effects from an evolutionary perspective. The overarching aim is to integrate the evidence which suggests epigenetic inheritance modulates lifespan/longevity with the main evolutionary theories of ageing

Effects of obesity on cholesterol metabolism and its implications for healthy ageing.

This article has been published in a revised form in Nutrition Research Reviews [https://doi.org/10.1017/S0954422419000258]. This version is free to view and download for private research and study only. Not for re-distribution or re-use. © copyright holder.The last few decades have witnessed a global rise in the number of older people. Despite this demographic shift, morbidity within this population group is high. Many factors influence healthspan; however an obesity pandemic is emerging as a significant determinant of older peoples’ health. It is well established obesity adversely effects several metabolic systems. However, due to its close association with overall cardiometabolic health, the impact obesity has on cholesterol metabolism needs to be recognised. The aim of this review is to critically discuss the effects obesity has on cholesterol metabolism and to reveal its significance for healthy ageing

Racial disparities in problems with voting

Electoral laws in the United States are causing hurdles for participation which affect the racial minority population in greater degree than for the white population. This thesis looks at racial disparities in problems with voting with data from the 2020 Cooperative Election Study. A logistic fixed effect regression model shows the results of racial minorities who are Black, Hispanic, and Two or more races have statistically significant increased odds in having problems with voting, compared to White. When adding the structural variables, some of this is explained by low education, living in urban areas and being younger, controlled for the state the respondent lives in. There are still significant results that Hispanics and Two or more races have increased odds in having problems with voting, compared to White, controlled for education, rurality, age, and state. These laws excludes eligible voters from the American democracy. Voting is a cornerstone in a democracy and should represent the will of all the people. Exclusion of racial minorities violates with the definition of Robert Dahl, that a democracy “is the continuing responsiveness of the government to the preferences of its citizens, considered as political equals” (Dahl 1971, 1). When excluded, racial minorities are not political equals, the government is not being responsive to their preferences, and they don’t possess the opportunity to vote them out. Inclusion should always be desirable as a democratic ideal

Cardiovascular disease and healthy ageing

Cardiovascular diseases are main cause of morbidity and mortality in the Western World. Cardiovascular disease increases in its prevalence with age and the burden of this condition is set to increase with an Ageing global population. There are many factors that impact cardiovascular disease risk. The aim of this brief commentary is to explore some of these factors; specifically, we will examine the role of social status, nutrition and, psychological stress in modulating cardiovascular disease risk. Our aim is to emphasise the multidimensional nature of this condition and to stress that a more complete understanding of the mechanisms which underpin its pathology can only be achieved by adopting an integrated approach which treats the progression of this disease in a more holistic fashion

Computationally modeling lipid metabolism and aging: A mini-review

This is an Version of Record of an article published in Computational and Structural Biotechnology Journal in 15 November 2014, available online: http://dx.doi.org/10.1016/j.csbj.2014.11.006 This is an open-access article distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/ licenses/by/3.0/One of the greatest challenges in biology is to improve the understanding of the mechanisms which underpin aging and how these affect health. The need to better understand aging is amplified by demographic changes, which have caused a gradual increase in the global population of older people. Aging western populations have resulted in a rise in the prevalence of age-related pathologies. Of these diseases, cardiovascular disease is the most common underlying condition in older people. The dysregulation of lipid metabolism due to aging impinges significantly on cardiovascular health. However, the multifaceted nature of lipid metabolism and the complexities of its interaction with aging make it challenging to understand by conventional means. To address this challenge computational modeling, a key component of the systems biology paradigm is being used to study the dynamics of lipid metabolism. This mini-review briefly outlines the key regulators of lipid metabolism, their dysregulation, and how computational modeling is being used to gain an increased insight into this system

The role of DNA methylation in ageing and cancer

This article has been accepted for publication and will appear in a revised form, subsequent to peer review and/or editorial input by Cambridge University Press, in Proceedings of the Nutrition Society published by Cambridge University Press. Copyright Cambridge University Press.The aim of the present review paper is to survey the literature related to DNA methylation, and its association with cancer and ageing. The review will outline the key factors, including diet, which modulate DNA methylation. Our rationale for conducting this review is that ageing and diseases, including cancer, are often accompanied by aberrant DNA methylation, a key epigenetic process, which is crucial to the regulation of gene expression. Significantly, it has been observed that with age and certain disease states, DNA methylation status can become disrupted. For instance, a broad array of cancers are associated with promoter-specific hypermethylation and concomitant gene silencing. This review highlights that hypermethylation, and gene silencing, of the EN1 gene promoter, a crucial homeobox gene, has been detected in various forms of cancer. This has led to this region being proposed as a potential biomarker for diseases such as cancer. We conclude the review by describing a recently developed novel electrochemical method that can be used to quantify the level of methylation within the EN1 promoter and emphasise the growing trend in the use of electrochemical techniques for the detection of aberrant DNA methylation