End-Capping Strategies for Triggering End-to-End Depolymerization of Polyglyoxylates

Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfi de, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to multiple stimuli, either simultaneously or independently. Incorporation of a cross-linkable trialkene endcap enabled the preparation of networks that could subsequently be depolymerized. Finally, high molar mass PEtG could be depolymerized by mechanical stimulation independent of the end-cap. It is anticipated that the versatility in end-capping strategies and potential depolymerization stimuli will not only expand PEtG’ s utility for different applications but also be useful for other classes of end-to-end depolymerizable polymers

A review and critique of academic lab safety research

Over the past ten years, there have been several high-profile accidents in academic laboratories around the world, resulting in significant injuries and fatalities. The aftermath of these incidents is often characterized by calls for reflection and re-examination of the academic discipline’s approach to safety research and policy. However, the study of academic lab safety is still underdeveloped and necessary data about changes in safety attitudes and behaviours has not been gathered. This Review article critically examines the state of academic chemical safety research from a multifactorial stance, including research on the occurrence of lab accidents, contributors to lab accidents, the state of safety training research and the cultural barriers to conducting safety research and implementing safer lab practices. The Review concludes by delineating research questions that must be addressed to minimize future serious academic laboratory incidents as well as stressing the need for committed leadership from our research institutions

L-tryptophan adsorption differentially changes the optical behaviour of pseudo-enantiomeric cysteine-functionalized quantum dots: Towards chiral fluorescent biosensors

Water-soluble chiral graphene quantum dots (GQDs) with a strong blue emission were synthesized by covalently immobilizing l-cysteine or d-cysteine onto the GQDs. Either the amine or the thiol group of cysteine was used to make the bond through amide coupling or thiol-ene click chemistry respectively. The functionalized chiral GQDs were the characterized by FT-IR and UV–vis. The enantiomeric pairs exhibit equal but opposite bands in circular dichroism spectra suggesting that there is no difference in the efficacy of conjugation. The fluorescent response of these chiral GQDs when exposed to l-tryptophan was then studied. The fluorescence of the amide-conjugated GQDs was quenched with the addition of l-Trp regardless of which enantiomer of cysteine was present on the surface. The thiol-linked d- Cys GQDs fluorescence was also quenched on exposure to l-Trp, but the fluorescence of the thiol-linked l-Cys GQDs was unaffected under the same conditions

Self-Destructing Polymers: Creating Thermally Sensitive End-Caps

Self-Destructing Polymers: Creating Thermally Sensitive End-Caps Trant Team – Rose Anne Fayoumi A broad and booming field of research and innovation, polymer science blends chemistry, physics and engineering and breeds countless modern materials and devices. Likewise, the degradation of these polymers is a field of interest due to the consideration of environmental, medical and economical factors. Nowadays, conventional biodegradable polymers degrade, but require an enzyme to cleave every single connection between monomers before complete disintegration. Numerous stimulus events are thus necessary, promoting inefficient and slow environmental degradation that can take weeks to years. To address this, the Trant Team is developing a new class of polymers that self-destruct “on-demand” using organic chemistry. Only one stimulus event, removing the end, destabilizes the polymer, which leads it to quickly disintegrate in only a few hours. These self-immolative polymers hence need ends with a functionality that can be triggered, as the “push” required to initiate the domino-like effect. In our case, this push is an elevated temperature that causes the end-cap to destabilize and degrade. Elevated temperatures can be induced via intersecting laser beams or magnetic fields to create heat in desired areas. In addition, the optimal temperature for the degradation of each end-cap will be determined through kinetic studies. Ultimately, specific reversible chemical reactions will be exploited to create such thermally-sensitive end-caps, allowing “on-demand” degradation of the polymer’s constituents by elevated temperatures. Accordingly, this innovation could potentially lead to endless possibilities and applications, including therapeutic, pharmaceutical, and biomedical applications. At this stage, however, it is too early to report findings as research and data collection are currently in progress. In spite of this, the presentation will review our preliminary results with this technology as well as shed light on its various potential applications

Self-Destructing Polymers: Creating Thermally Sensitive End-Caps

Self-Destructing Polymers: Creating Thermally Sensitive End-Caps Trant Team – Rose Anne Fayoumi A broad and booming field of research and innovation, polymer science blends chemistry, physics and engineering and breeds countless modern materials and devices. Likewise, the degradation of these polymers is a field of interest due to the consideration of environmental, medical and economical factors. Nowadays, conventional biodegradable polymers degrade, but require an enzyme to cleave every single connection between monomers before complete disintegration. Numerous stimulus events are thus necessary, promoting inefficient and slow environmental degradation that can take weeks to years. To address this, the Trant Team is developing a new class of polymers that self-destruct “on-demand” using organic chemistry. Only one stimulus event, removing the end, destabilizes the polymer, which leads it to quickly disintegrate in only a few hours. These self-immolative polymers hence need ends with a functionality that can be triggered, as the “push” required to initiate the domino-like effect. In our case, this push is an elevated temperature that causes the end-cap to destabilize and degrade. Elevated temperatures can be induced via intersecting laser beams or magnetic fields to create heat in desired areas. In addition, the optimal temperature for the degradation of each end-cap will be determined through kinetic studies. Ultimately, specific reversible chemical reactions will be exploited to create such thermally-sensitive end-caps, allowing “on-demand” degradation of the polymer’s constituents by elevated temperatures. Accordingly, this innovation could potentially lead to endless possibilities and applications, including therapeutic, pharmaceutical, and biomedical applications. At this stage, however, it is too early to report findings as research and data collection are currently in progress. In spite of this, the presentation will review our preliminary results with this technology as well as shed light on its various potential applications

Which colour do you want for your cells, pink or blue? -Improving the synthesis of cyanine dyes

Cyanine dyes are fluorescent compounds commonly used in biosensors because of their great compatibility in vivo and high extinction coefficient, which has made it the perfect choice for our previous studies investigations into prostate cancer. Although cyanine dyes are commercially available, they are very expensive with only few suppliers and problematic synthesis. To facilitate our cancer research projects, we have sought to develop improved synthetic routes to these useful compounds. In this presentation I will describe our work towards the improved synthesis of some of the cyanine dyes, Cy3 and Cy5. The difficulties (and successes) of the synthesis will be analysed and extension of these methods to other members of the family will be discussed

Functionalizable molecular tubing synthesis combining self-immolative polymers and rotaxanes

Carbon nanotubes are used daily for many applications such as support for automotive parts, water filtration and energy storage, due to their high tensile strength and lightweight nature. However, a limitation lies in their structure since pure carbon does not allow for easy nor high yielding ways to add functional groups in the molecular structure. A variation of organic molecular tubing with modifiable groups can be constructed from synthesizing polyrotaxanes, which are repeating units of interlocked self-immolative polymers (SIPs) and macrocyclic compounds. SIPs are molecules which are specifically end capped for stability until it encounters a specific environmental condition that causes the polymer to spontaneously degrade. Endcaps can be selectively chosen to destabilize under certain stimuli such as enzymes, UV light and chemical analytes allowing for SIP’s to be used in a variety of functions such as drug delivery. Currently, most research focus on linear SIP’s to form spheres encapsulating drug molecules that deliver into cancer cells. Our work introduces a novel benzimidazole-backbone, resulting in a SIP that includes blocky ends which physically locks functionalized macrocycles in place to allow for cross linkage and any post-modifications. Application of a specific stimulus would allow for the inner bulky groups to degrade and ultimately leave a hollow molecular tube with the specific functionalizations desired