Development of novel advanced flow control systems on centrifugal microfluidic platforms for nucleic acid testing

In this work the development of novel flow control methods in centrifugal microfluidic systems for the nucleic acid testing are demonstrated. Nucleic acids make excellent biomarkers for the identification of numerous diseases, but their detection is a lengthy and labour intensive process. Centrifugal microfluidics has emerged as a highly useful tool in the area of biomedical diagnostics; however there are still limitations when it comes to sample preparation on these Lab-on-a-Disc systems. This is especially important in nucleic acid testing, where the main bottleneck in performing these processes on microfluidic devices is in sample preparation. Nucleic acid testing can be broken into three stages; extraction, purification and detection. To this end, this work outlines the development of two novel centrifugal routing systems for nucleic acid purification, through the integration of functional materials. The first is a solvent-selective router which integrated two solvent specific membrane valves. The capability of the system to purify total RNA with significant integrity and concentration was shown. The second system integrated multi-layer Graphene Oxide (GO) membranes into our Lab-on-a-Disc devices. Using this, two unique properties of the GO were investigated; its solvent selectivity and air impermeability. Finally, a novel, centrifugo-pneumatic scheme for solvent-selective routing of organic and aqueous flows was demonstrated. Also shown is the development of two separate extraction platforms. The first was a centrifugo-pneumatic ‘μHomogenizer’, which implements a 3-phase fluid extraction protocol of RNA. This system integrates chemical lysis and separation of the RNA containing aqueous phase and shows significant improvement over its time-consuming and labour intensive benchtop alternate. The second was the development of a mechanical lysis method that utilises a rotor stator grinding mill driven by the spindle motor. This system can be used for general lysis of a wide range of bacteria but would be of significant benefit for armoured cells

Identification of sleep apnea events using discrete wavelet transform of respiration, ECG and accelerometer signals

Sleep apnea is a common sleep disorder in which patient sleep patterns are disrupted due to recurrent pauses in breathing or by instances of abnormally low breathing. Current gold standard tests for the detection of apnea events are costly and have the addition of long waiting times. This paper investigates the use of cheap and easy to use sensors for the identification of sleep apnea events. Combinations of respiration, electrocardiography (ECG) and acceleration signals were analysed. Results show that using features, formed using the discrete wavelet transform (DWT), from the ECG and acceleration signals provided the highest classification accuracy, with an F1 score of 0.914. However, the novel employment of just the accelerometer signal during classification provided a comparable F1 score of 0.879. By employing one or a combination of the analysed sensors a preliminary test for sleep apnea, prior to the requirement for gold standard testing, can be performed

Disc-embedded grinding mill towards process integtrated hydro-mechanical cell lysis on centrifugal microfluidic platforms

For the first time we utilize the spindle motor intrinsic to centrifugal microfluidic systems to drive a grinding mill for cell lysis in a stator-rotor concept. This mechanical concept particularly enables the lysis of armored cells and, as a further benefit, avoids the addition of chemicals that potentially inhibit subsequent reactions. As a proof of concept we demonstrate the lysis of the silica-shelled algae Phaeodactylum Tricornutum

Automated on-disc total RNA extraction from whole blood towards point-of-care for early-stage diagnostics

We present a novel integrated, centrifugo-pneumatic micro-homogenizer (“μHomogenizer”) for automated sample preparation and total RNA extraction from whole blood. Using a Trizol based protocol, this novel μHomogenizer efficiently lyses whole blood spiked with E. coli, retains the organic-mixed fraction and yields the aqueous phase with the total RNA content. By the interplay of microfluidic design and a protocol of rotational frequencies, we concatenate (and parallelize) a sequence of five subsequent liquid handling operations that complete in less than 10 minutes. A comparison of the total nucleotide content yields similar performance as conventional, essentially manual off-disc sample preparation methods

Optical sensing system based on wireless paired emitter detector diode device and ionogels for lab-on-a-disc water quality analysis

This work describes the first use of a wireless paired emitter detector diode device (PEDD) as an optical sensor for water quality monitoring in a lab-on-a-disc device. The microfluidic platform, based on an ionogel sensing area combined with a low-cost optical sensor is applied for pH (quantitative) and qualitative turbidity monitoring of water samples at the point-of-need. The autonomous capabilities of the PEDD system, combined with the portability and wireless communication of the full device, provide the flexibility needed for on-site water testing. Water samples from local fresh and brackish sources were successfully analysed using the device, showing very good correlation with standard bench-top systems

Solvent-selective routing for centrifugally automated solid-phase purification of RNA

The final publication is available at Springer via https://doi.org/10.1007/s10404-014-1477-9.We present a disc-based module for rotationally controlled solid-phase purification of RNA from cell lysate. To this end, multi-stage routing of a sequence of aqueous and organic liquids into designated waste and elution reservoirs is implemented by a network of strategically placed, solvent-selective composite valves. Using a bead-based stationary phase at the entrance of the router, we show that total RNA is purified with high integrity from cultured MCF7 and T47D cell lines, human leucocytes and Haemophilus influenzae cell lysates. Furthermore, we demonstrate the broad applicability of the device through the in vitro amplification of RNA purified on-disc using RT-PCR and NASBA. Our novel router will be at the pivot of a forthcoming, fully integrated and automated sample preparation system for RNA-based analysis.Peer reviewe

Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study

Summary Background The risk of individuals having adverse effects from drug use (eg, alcohol) generally depends on the frequency of use and potency of the drug used. We aimed to investigate how frequent use of skunk-like (high-potency) cannabis in south London affected the association between cannabis and psychotic disorders

Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study

Summary Background The risk of individuals having adverse effects from drug use (eg, alcohol) generally depends on the frequency of use and potency of the drug used. We aimed to investigate how frequent use of skunk-like (high-potency) cannabis in south London affected the association between cannabis and psychotic disorders

Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study

Summary Background The risk of individuals having adverse effects from drug use (eg, alcohol) generally depends on the frequency of use and potency of the drug used. We aimed to investigate how frequent use of skunk-like (high-potency) cannabis in south London affected the association between cannabis and psychotic disorders

Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study

Summary Background The risk of individuals having adverse effects from drug use (eg, alcohol) generally depends on the frequency of use and potency of the drug used. We aimed to investigate how frequent use of skunk-like (high-potency) cannabis in south London affected the association between cannabis and psychotic disorders