Accurate whole human genome sequencing using reversible terminator chemistry.

DNA sequence information underpins genetic research, enabling discoveries of important biological or medical benefit. Sequencing projects have traditionally used long (400-800 base pair) reads, but the existence of reference sequences for the human and many other genomes makes it possible to develop new, fast approaches to re-sequencing, whereby shorter reads are compared to a reference to identify intraspecies genetic variation. Here we report an approach that generates several billion bases of accurate nucleotide sequence per experiment at low cost. Single molecules of DNA are attached to a flat surface, amplified in situ and used as templates for synthetic sequencing with fluorescent reversible terminator deoxyribonucleotides. Images of the surface are analysed to generate high-quality sequence. We demonstrate application of this approach to human genome sequencing on flow-sorted X chromosomes and then scale the approach to determine the genome sequence of a male Yoruba from Ibadan, Nigeria. We build an accurate consensus sequence from >30x average depth of paired 35-base reads. We characterize four million single-nucleotide polymorphisms and four hundred thousand structural variants, many of which were previously unknown. Our approach is effective for accurate, rapid and economical whole-genome re-sequencing and many other biomedical applications.

Simultaneous quartz crystal microbalance impedance and electrochemical impedance measurements. Investigation into the degradation of thin polymer films.

The reproducible degradation of thin polymer films in the presence of an analyte or a reaction product of an analyte has potential applications in the development of highly sensitive, disposable biosensors. In this study, a novel combination of quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS) has been developed to monitor the degradation of thin polymer films. Unlike a conventional QCM, the instrument described here allows rapid in situ measurement of quartz crystal impedance spectra. Simultaneously, classical electrochemical impedance spectra are measured in situ, affording the polymer film capacitance and bulk resistance. The combination of QCM impedance and classical EIS provides a wealth of information about the process of degradation of thin polymer films such as mass variation, swelling, delamination, viscoelasticity, and pore formation. Three different systems have been analyzed with this experimental setup; in two of the systems, polymer degradation was promoted by hydrolytic enzymes, and in the third one by a pH change. The results obtained show that the degradation of these three systems follows very different mechanisms. It is also underlined how the complementary information obtained by the two techniques allows a detailed description of the dissolution process.