Uncategorized

Intriguing Flexible Devices Based On Mechanoluminescence

Luminescence
Photo: Pixabay

Mechanoluminescence (ML), also called triboluminescence (TL), refers to the phenomenon/process that materials could emit light under mechanical stimuli, e.g., friction, stretch, compression, impact, etc. The ML materials could utilize the ubiquitous mechanical energy in daily life to generate light emissions, avoiding the requirement of an artificial photon- or electron-excitation source as that in photoluminescence (PL) or electroluminescence (EL). Therefore, ML materials show great advantages in energy saving and environmental protection.

For practical applications, ML crystals or powders are required to composite with bulk matrices to generate structural non-destructive ML. Among the fabricated ML composites, elastomer-based ones have attracted increasing attention owing to the rising requirement of incorporating stress sensing characteristic into flexible/wearable devices. The present ML elastomer composites mainly employ transition metal ion doped sulfides (TM-sulfides) as the luminescent components because of their intense ML intensity. However, the TM-sulfides usually have poor chemical stability and may cause severe environmental pollution as well as lack of rich emission color.

Theoretically, rare earth doped oxides (RE-oxides) are promising alternatives because of their high chemical stability, nontoxicity, and abundant energy levels. It is essential to develop efficient and ideally multicolored ML of RE-oxide based elastomer composites, so that flexible devices may possess remarkable and environmentally friendly mechanical responsive optical characteristics.  Read the full story at Science Trends.

 

Polymer Program Seminar Series 2/9/2018

Dr. Igor L. Medintz
Dr. Igor L. Medintz, U.S. Naval Research Laboratory

February 9, 2018
11.00am in  IMS 20

Enhancing Enzymatic Activity with Nanoparticle Scaffolds – Towards Cell Free Biocatalysis

Igor L. Medintz
Center for Bio/Molecular Science and Engineering
U.S. Naval Research Laboratory
Washington D.C.  U.S.A.
(Igor.medintz@nrl.navy.mil)

ABSTRACT
Enzymes and especially multienzyme pathways are of tremendous interest for the production of industrial chemicals and in the development of metabolic sensors. One primary focus of synthetic biology is to design enzymatic production capabilities in a “plug and play” format within cellular systems.  Living cellular systems, however, can suffer from toxicity, competing pathways and sometimes an inability to mix enzymes from different species.  Application of enzymes for industrial catalysis is often achieved by immobilization on a surface since this often provides stability and facilitates purification and reuse of the enzymes from the reaction mixture. Unfortunately, immobilization of enzymes on large planar surfaces often results in loss of enzymatic activity.  We seek to create cell-free enzyme systems that can circumvent these issues in a “plug and play” format where enzymes are assembled on nanoparticle surfaces but still overcome diffusion and stability issues. We, and others, have demonstrated that immobilization of enzymes or substrate on nanoparticles often results in enhanced enzymatic activity relative to the free enzyme in solution.  Mechanistic studies of this phenomena will be presented starting with substrate on nanoparticles and then progressing to the converse approach. Examples of multienzyme cascades assembled on nanoparticles that appear to access substrate channeling phenomena will also be presented.  The challenges of characterizing and describing these complex organic/inorganic supramacromolecular systems will also be discussed in the context of further studies moving forward.

Host: Elena Dormidontova (elena@uconn.edu) and Mu-Ping Nieh (mu-ping.nieh@uconn.edu)