We describe, for the first time, stimulus-responsive hydrogel-forming microneedle (MN) arrays that enable delivery of a clinically relevant model drug (ibuprofen) upon application of light. MN arrays were prepared using a polymer prepared from 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) by micromolding. The obtained MN arrays showed good mechanical properties. The system was loaded with up to 5% (w/w) ibuprofen included in a light-responsive 3,5-dimethoxybenzoin conjugate. Raman spectroscopy confirmed the presence of the conjugate inside the polymeric MN matrix. In vitro, this system was able to deliver up to three doses of 50 mg of ibuprofen upon application of an optical trigger over a prolonged period of time (up to 160 h). This makes the system appealing as a controlled release device for prolonged periods of time. We believe that this technology has potential for use in "on-demand" delivery of a wide range of drugs in a variety of applications relevant to enhanced patient care.

The use of externally or internally applied triggers of drug delivery to biomaterials has significant potential for improved delivery modalities and infection resistance.

"Chemistry-on-the-complex" synthetic methods have allowed the selective addition of 1-ethynylpyrene appendages to the 3-, 5-, 3,8- and 5,6-positions of Ir -coordinated 1,10-phenanthroline via Sonogashira cross-coupling. The resulting suite of complexes has given rise to the first rationalization of their absorption and emission properties as a function of the number and position of the pyrene moieties. Strong absorption in the visible region (e.g. 3,8-substituted Ir-3: λ =481 nm, ϵ=52 400 m cm ) and long-lived triplet excited states (e.g. 5-substituted Ir-2: τ =367.7 μs) were observed for the complexes in deaerated CH Cl . On testing the series as triplet sensitizers for triplet-triplet annihilation upconversion, those Ir complexes bearing pyrenyl appendages at the 3- and 3,8-positions (Ir-1, Ir-3) were found to give optimal upconversion quantum yields (30.2 % and 31.6 % respectively).

A long-lived dual phosphorescence triplet photosensitiser: for TTA upconversion and PDT.

A series of Ir(III) complexes, based on 1,10-phenanthroline featuring aryl acetylene chromophores, were prepared and investigated as triplet photosensitizers. The complexes were synthesized by Sonogashira cross-coupling reactions using a "chemistry-on-the-complex" method. The absorption properties and luminescence lifetimes were successfully tuned by controlling the number and type of light-harvesting group. Intense UV/Vis absorption was observed for the Ir(III) complexes with two light-harvesting groups at the 3- and 8-positions of the phenanthroline. The asymmetric Ir(III) complex (with a triphenylamine (TPA) and a pyrene moiety attached) exhibited the longest lifetime. Red emission was observed for all the complexes in deaerated solutions at room temperature. Their emission at low temperature (77 K) and nanosecond time-resolved transient difference absorption spectra revealed the origin of their triplet excited states. The singlet-oxygen ((1) O2 ) sensitization and triplet-triplet annihilation (TTA)-based upconversion were explored. Highly efficient TTA upconversion (ΦUC =28.1 %) and (1) O2 sensitization (ΦΔ =97.0 %) were achieved for the asymmetric Ir(III) complex, which showed intense absorption in the visible region (λabs =482 nm, ϵ=50900 m(-1)  cm(-1) ) and had a long-lived triplet excited state (53.3 μs at RT).

“Chemistry‐on‐the‐complex” synthetic methods have allowed the selective addition of 1‐ethynylpyrene appendages to the 3‐, 5‐, 3,8‐ and 5,6‐positions of IrIII‐coordinated 1,10‐phenanthroline via Sonogashira cross‐coupling. The resulting suite of complexes has given rise to the first rationalization of their absorption and emission properties as a function of the number and position of the pyrene moieties. Strong absorption in the visible region (e.g. 3,8‐substituted Ir‐3: λabs=481 nm, ϵ=52 400 m−1 cm−1) and long‐lived triplet excited states (e.g. 5‐substituted Ir‐2: τT=367.7 μs) were observed for the complexes in deaerated CH2Cl2. On testing the series as triplet sensitizers for triplet–triplet annihilation upconversion, those IrIII complexes bearing pyrenyl appendages at the 3‐ and 3,8‐positions (Ir‐1, Ir‐3) were found to give optimal upconversion quantum yields (30.2 % and 31.6 % respectively).

A series of RuII complexes containing extended 1,10‐phenanthroline ligands with triphenylamine (TPA) and/or pyrene as light‐harvesting chromophores, were synthesised and investigated in triplet photosensitising applications. “Chemistry‐on‐the‐complex” methods were employed using Sonogashira cross‐coupling reactions. Tunable absorption and triplet lifetimes were achieved depending on the type and number of the chromophores. Intense absorption in the visible region was common to the generated complexes. Those RuII complexes containing only TPA appendages showed much shorter triplet lifetimes (τT<0.6 μs) than those containing pyrene (τT up to 148 μs). The complexes were explored as triplet photosensitisers for singlet‐oxygen (1O2) photosensitisation and triplet–triplet annihilation based upconversion applications. The best performing complex, Ru‐5, with a single pyrene chromophore, displayed the highest 1O2 quantum yield (ΦΔ=84.4 %) and an attractive upconversion quantum yield (ΦUC=14.7 %). A comparison of the results with those of analogous IrIII complexes comprising the same large N^N coordinating ligands showed that both sets of complexes exhibit the same ligand‐dependent trends in behaviour. The implication is that synthetically accessible RuII complexes might be effective model systems for predicting those ligand frameworks likely to give the highest performing IrIII‐based triplet photosensitisers.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThe kinetics of the degradation of a homologous series of Poly phenylene vinylenes in which the phenylene units of the PPV structure are systematically substituted by naphthyl and anthyrl units is presented. Degradation is monitored according to the decay of the long wavelength absorption maximum upon illumination with UV radiation. Compared to Toluene solution, the photo-degradation is seen to be accelerated in Chloroform solution. All decays are fitted with first order kinetics. It is found that all substitutions improve the stability of the vinylene polymers against decay.In particular the highly electro-negative naphthyl group serves to drastically increase the stability due to electron depletion across the vinyl bond. The decay rate is shown to correlate well with the variation of the electronic properties of the backbone and with the reduction of vinylene bond strength as measured using Raman spectroscopy.