Development of novel AIEgens based on benzylidene-methyloxazolones and isoquinolinium salts and exploration of their biological applications

Abstract

To tackle world-challenging problems, luminescent materials have played a vital role in the promotion of scientific discoveries and technological innovations. Practically, traditional luminogens often face a problem of aggregation-caused quenching (ACQ), resulting a reduction or diminishment of luminescence and thus limiting their practical applications. Circumventing the notorious ACQ effect, luminogens with aggregation-induced emission characteristics (AIEgens) have become intriguing with a rapid expansion in applications ranging from optoelectronics, chemo/biosensing to bioimaging. However, to tailor for specific high-tech applications and deepen the mechanistic understanding of AIEgens, there is a high demand on the developments of novel AIEgens with easy preparation and functionalization. In this thesis, two series of AIEgens were developed. Their working mechanism and various applications, especially biological applications, were investigated. Based on green fluorescence protein chromophore analogues benzylidene-oxazolone, a series of AIEgens were synthesized with solid quantum yield of up to 50% and emission wavelength of up to 635 nm. Their working mechanism were carefully deciphered. Further, through minor modifications, a two-photon AIE bioprobe was developed for specific lipid droplet imaging in cells and tissues. Also, we prepared a series of isoquinolinium salts-based AIEgens with high structural stability via a simple one-pot reaction. With the merits of visible light excitation, large Stokes shift, high quantum yield, tunable color and sufficient two-photon absorption of near-infrared light, we found their various applications in mechanochromic rewritable paper, mitochondrial targeting cell imaging and bacterial imaging. Interestingly, these molecules exhibited high viscosity-sensitivity and were further utilized as sensors for extracellular and intracellular microviscosity sensing. Among them, a simple AIEgen was developed for image-guided two-photon excited photodymanic therapy for precise cancer treatment.

Date of Award	2017
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology