Directly interrogating single quantum dot labelled UvrA2 molecules on DNA tightropes using an optically trapped nanoprobe

AbstractIn this study we describe a new methodology to physically probe individual complexes formed between proteins and DNA. By combining nanoscale, high speed physical force measurement with sensitive fluorescence imaging we investigate the complex formed between the prokaryotic DNA repair protein UvrA2 and DNA. This approach uses a triangular, optically-trapped “nanoprobe” with a nanometer scale tip protruding from one vertex. By scanning this tip along a single DNA strand suspended between surface-bound micron-scale beads, quantum-dot tagged UvrA2 molecules bound to these ‘”DNA tightropes” can be mechanically interrogated. Encounters with UvrA2 led to deflections of the whole nanoprobe structure, which were converted to resistive force. A force histogram from all 144 detected interactions generated a bimodal distribution centered on 2.6 and 8.1 pN, possibly reflecting the asymmetry of UvrA2’s binding to DNA. These observations successfully demonstrate the use of a highly controllable purpose-designed and built synthetic nanoprobe combined with fluorescence imaging to study protein-DNA interactions at the single molecule level.</jats:p

Re and^99mTc complexes of BodP₃ – multi-modality imaging probes

A fluorescent tridentate phosphine, BodP(3) (2), forms rhenium complexes which effectively image cancer cells. Related technetium analogues are also readily prepared and have potential as dual SPECT/fluorescent biological probes

Preprint: Near infrared-light treatment alters mitochondrial homeostasis to induce senescence in breast cancer cells

The application of near infrared (NIR)-light to living systems has been suggested as a potential method to enhance tissue repair, decrease inflammation, and possibly mitigate cancer therapy-associated side effects. In this study, we examined the effect of exposing three cell lines: breast cancer (MCF7), non-cancer breast cells (MCF10A), and lung fibroblasts (IMR-90), to 734 nm NIR-light for 20 minutes per day for six days, and measuring changes in cellular senescence. Positive senescent populations were induced using doxorubicin. Flow cytometry was used to assess relative levels of senescence together with mitochondria-related variables. Exposure to NIR-light significantly increased the level of senescence in MCF7 cells (13.5%; P<0.01), with no observable effects on MCF10A or IMR-90 cell lines. NIR-induced senescence was associated with significant changes in mitochondria homeostasis, including raised ROS level (36.0%; P<0.05) and mitochondrial membrane potential (14.9%; P<0.05), with no changes in mitochondrial Ca2+. These results suggest that NIR-light exposure can significantly arrest the proliferation of breast cancer cells via inducing senescence, while leaving non-cancerous cell lines unaffected

High yield vesicle packaged recombinant protein production from E. coli.

We describe an innovative system that exports diverse recombinant proteins in membrane bound vesicles from E. coli. These recombinant vesicles compartmentalise proteins within a micro-environment that allows production of otherwise challenging insoluble, toxic, or disulphide-bond containing proteins from bacteria. The release of the inducible vesicle packaged soluble protein supports isolation from the culture within an environment allowing long term storage of active protein. This technology results in high-yields of vesicle packaged soluble functional proteins for efficient downstream processing for a wide range of applications from discovery science to applied biotechnology and medicine