o-Nitrobenzyl Alcohol Derivatives: Opportunities in Polymer and Materials Science

Abstract

Polymers featuring photolabile groups are the subject of intense research because they allow the alteration of polymer properties simply by irradiation. In particular, the o-nitrobenzyl group (o-NB) is utilized frequently in polymer and materials science. This Perspective pays particular attention to the increasing utilization of this chemical group in polymer chemistry. It covers the use of (i) o-NB-based cross-linkers for photodegradable hydrogels, (ii) o-NB side chain functionalization in (block) copolymers, (iii) o-NB side chain functionalization for thin film patterning, (iv) o-NB for self-assembled monolayers, (v) photocleavable block copolymers, and (vi) photocleavable bioconjugates. We conclude with an outlook on new research directions in this rapidly expanding area.

Photodegradable Macromers and Hydrogels for Live Cell Encapsulation and Release

“…o-NB groups are widely used as photocages in the presence of live cells, [8][9][10][11][12] and also as degradable linkages in polymer materials 13 . Several different o-NB groups have been reported [14][15][16] , and small modifications to the structure of the o-NB linker have a significant impact on the photolysis rate.…”

“…For example, the half-life of an o-NB linker with a primary benzylic group is approximately 25 times that of one with a secondary benzylic group (X= −NHR, buffer, pH=7). 13 When X=RSO 3 -, the apparent rate constant of photodegradation (k app ) is nearly 40 times higher for a secondary benzylic group compared to a primary group (solvent: CDCl 3 ). 17 Increasing the number of aryl ethers from one (R 1 =−CO2H, X= −SR, R 2 =−OR, R 3 =−H) to two (R 2 =−OR, R 3 =−OR) decreases the quantum yield of the o-NB group at 365 nm by 30%.…”

Deep UV generation and direct DNA photo-interaction by harmonic nanoparticles in labelled samples

“…Given the unconstrained tunability of the HNPs nonlinear conversion process, this approach can be extended to selectively photo-activate molecules at the surface or in the vicinity of HNPs to further diversify the prospective therapeutic action. 3 Here we show that by tuning the frequency of ultrashort laser pulses from infrared (IR) to visible (both harmless), SH generation leads respectively to diagnostics (imaging) and therapy (phototoxicity). Specifically, we report in situ generation of deep ultraviolet (DUV) radiation (270 nm) in human-derived lung cancer cells treated with bismuth ferrite (BiFeO 3 , BFO) HNPs upon pulsed laser irradiation in the visible spectrum, at 540 nm.…”

Fabrication of Upconverting Hybrid Nanoparticles for Near-Infrared Light Triggered Drug Release

“…o-NB esters are a typical photolabile group, which usually yields carboxylic acid under irradiation of UV light with onitrosobenzaldehyde as a byproduct [11]. When P(NIPAMco-NBA) are treated with UV light, they will convert to P(NIPAM-co-AA) (Scheme 1), where the AA denotes acrylic acid.…”

“…Among the various stimuli, light is a typical external stimulus and has many superior characters. For example, light can be easily controlled and regulated by external apparatuses, which will offer the temporal and spatial selectivity [6][7][8][9][10]; light can induce various photochemical reactions, which makes it easy to exploit diversiform photosensitive materials [11][12][13][14]. However, the tissue penetration of light is low, and providing enough photons to the stimuli responsive nanoparticles in deep tissue is difficult.…”