Deep-red electrophosphorescence from a platinum(II)–porphyrin complex copolymerised with polyfluorene for efficient energy transfer and triplet harvesting

A series of polyfluorene-based polymers with a range of weight percentages (w/w) of a platinum(II)-containing porphyrin, 5,15-dimesityl-10,20-diphenylporphyrinato platinum(II) (MPP(Pt)), were synthesised and incorporated into organic light-emitting diodes. All polymers showed emission predominantly in the red/NIR region with only those polymers with porphyrin w/w of less than 2% showing residual tails at wavelengths lower than 600 nm, indicating increased emission from the porphyrin as w/w increases. The 2% loading of MPP(Pt) gave the highest efficiency LED (0.48%) and light output (2630 mW/m2)

Development of a minimally invasive microneedle-based sensor for continuous monitoring of β-lactam antibiotic concentrations in vivo

Antimicrobial resistance poses a global threat to patient health. Improving the use and effectiveness of antimicrobials is critical in addressing this issue. This includes optimizing the dose of antibiotic delivered to each individual. New sensing approaches that track antimicrobial concentration for each patient in real time could allow individualized drug dosing. This work presents a potentiometric microneedle-based biosensor to detect levels of β-lactam antibiotics in vivo in a healthy human volunteer. The biosensor is coated with a pH-sensitive iridium oxide layer, which detects changes in local pH as a result of β-lactam hydrolysis by β-lactamase immobilized on the electrode surface. Development and optimization of the biosensor coatings are presented, giving a limit of detection of 6.8 μM in 10 mM PBS solution. Biosensors were found to be stable for up to 2 weeks at -20 °C and to withstand sterilization. Sensitivity was retained after application for 6 h in vivo. Proof-of-concept results are presented showing that penicillin concentrations measured using the microneedle-based biosensor track those measured using both discrete blood and microdialysis sampling in vivo. These preliminary results show the potential of this microneedle-based biosensor to provide a minimally invasive means to measure real-time β-lactam concentrations in vivo, representing an important first step toward a closed-loop therapeutic drug monitoring system

Real-time continuous measurement of lactate through a minimally invasive microneedle patch: a phase I clinical study

Introduction Determination of blood lactate levels supports decision-making in a range of medical conditions. Invasive blood-sampling and laboratory access are often required, and measurements provide a static profile at each instance. We conducted a phase I clinical study validating performance of a microneedle patch for minimally invasive, continuous lactate measurement in healthy volunteers. Methods Five healthy adult participants wore a solid microneedle biosensor patch on their forearms and undertook aerobic exercise for 30 min. The microneedle biosensor quantifies lactate concentrations in interstitial fluid within the dermis continuously and in real-time. Outputs were captured as sensor current and compared with lactate concentrations from venous blood and microdialysis. Results The biosensor was well-tolerated. Participants generated a median peak venous lactate of 9.25 mmol/L (IQR 6.73–10.71). Microdialysate concentrations of lactate closely correlated with blood. Microneedle biosensor current followed venous lactate concentrations and dynamics, with good agreement seen in all participants. There was an estimated lag-time of 5 min (IQR −4 to 11 min) between microneedle and blood lactate measurements. Conclusion This study provides first-in-human data on use of a minimally invasive microneedle patch for continuous lactate measurement, providing dynamic monitoring. This low-cost platform offers distinct advantages to frequent blood sampling in a wide range of clinical settings, especially where access to laboratory services is limited or blood sampling is infeasible. Implementation of this technology in healthcare settings could support personalised decision-making in a variety of hospital and community settings

Synthesis and Exciton Dynamics of Donor-Orthogonal Acceptor Conjugated Polymers: Reducing the Singlet-Triplet Energy Gap

The presence of energetically low-lying triplet states is a hallmark of organic semiconductors. Even though they present a wealth of interesting photophysical properties, these optically dark states significantly limit optoelectronic device performance. Recent advances in emissive charge-transfer molecules have pioneered routes to reduce the energy gap between triplets and "bright" singlets, allowing thermal population exchange between them and eliminating a significant loss channel in devices. In conjugated polymers, this gap has proved resistant to modification. Here, we introduce a general approach to reduce the singlet-triplet energy gap in fully conjugated polymers, using a donor-orthogonal acceptor motif to spatially separate electron and hole wave functions. This new generation of conjugated polymers allows for a greatly reduced exchange energy, enhancing triplet formation and enabling thermally activated delayed fluorescence. We find that the mechanisms of both processes are driven by excited-state mixing between π-π*and charge-transfer states, affording new insight into reverse intersystem crossing.Part of this work was funded by EU project 679789 – 455 CONTREX, EC H2020 SYNCHRONICS (643238), EC H2020 SOLEDLIGHT (643791) and EPSRC (EP/M005143/1) A.J.M. was supported by the EPSRC (EP/456M01083X). J.M.F. was supported by EPSRC (EP/K016288/1). F.C. is a Royal Society Wolfson Research Merit Award holder. H.L.S. was supported by the Winton Programme 457 for the Physics of Sustainability. We are grateful to the Imperial College High Performance Computing Service (doi: 10.14469/hpc/2232)

Microneedle biosensors for real-time, minimally invasive drug monitoring of phenoxymethylpenicillin: a first-in-human evaluation in healthy volunteers

Background: We report the first-in-human evaluation of realtime penicillin monitoring using a microneedle-based beta-lactam biosensor.Methods: Participants taking phenoxymethylpenicillin (penicillin-V) at steady state had venous blood (via cannula, T=- 30,0,10,20,30,45,60,90,120,150,180,210,240mins) and extracellular fluid (ECF; via microdialysis, every 15mins) pharmacokinetic (PK) samples taken during one dosing interval. During this period, a solid microneedle betalactam biosensor was worn to provide real-time monitoring of ECF penicillin-V concentration. Penicillin-V concentration data obtained from the microneedles was calibrated using locally-estimated-scatter-plot smoothing and compared to free blood and microdialysis (gold standard) data. Penicillin-V PK for each method was evaluated using noncompartmental analysis. Area-under-the-concentration-time-curve (AUC), Cmax, and tmax were compared. Bias and limits of agreement were investigated with Bland-Altman plots. Microneedle biosensor limits of detection were estimated. The study was approved by London-HarrowRegional ethics committee (Ref:18/LO/0054, NCT03847610).Findings: Ten healthy volunteers participated. Mean (SD) age was 42 (14) years. Seven (70%) were male. Penicillin-V ECF determined through microdialysis and microneedle methods demonstrated similar Cmax (0.74mg/L vs. 0.64mg/L, p=0.53; 95%CI: -0.24;0.44), tmax (1.18hrs vs. 1.10hrs, p=0.79; 95%CI:-0.52;0.67), and AUC (1.54mg*h/L vs. 1.67 mg*h/L p=0.79;95%CI:-1.10;0.85). In total, 440 time points were compared with mean (95%CI) difference between measurements -0.15 mg/L (95%CI:-0.11;0.20). Mean (SD) penicillin-V AUC values for free serum and microneedle PK were similar at 1.77 (0.59) mg*h/L and 1.67 (1.06) mg*h/L, respectively (p=0.81; 95%CI:-0.77;0.97). Percentage coefficient of variation betweensensors within individuals was median (IQR) 7 (4-17)%. Limit of detection for the microneedles was estimated at 0.17 mg/L.Interpretation: This demonstrates proof-of-concept of real-time, microneedle sensing of penicillin in vivo. Future work will explore microneedle use in patient populations, their role in data generation to inform dosing recommendations, and their incorporation into closed-loop control systems for automated drug delivery

Energy-Transfer Pathways and Triplet Lifetime Manipulation in a Zinc Porphyrin/F8BT Hybrid Polymer

Triplet states are ubiquitous in organic electronics and their properties are increasingly being exploited to enhance device efficiencies. The difficulty in accurately probing triplet states dictates that more fundamental understanding is required of their properties. In this work, a hybrid co-polymer of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) with 10% by weight zinc porphyrin was synthesized and a transient absorption spectroscopy study performed. It was observed that a dual energy-transfer mechanism was active, whereby the ultimate fate of each photogenerated F8BT singlet exciton depended upon its distance to a porphyrin unit. F8BT excitons generated within the bulk of the F8BT polymer showed typical F8BT photophysics, with the small proportion of F8BT triplets created able to diffuse to and undergo triplet energy transfer to the porphyrin units. In contrast, F8BT singlet excitons formed within their diffusion length to a porphyrin unit displayed singlet energy transfer, followed by intersystem crossing to create the lower energy porphyrin triplet. Intriguingly, the F8BT–HAPAPP triplets generated have a lifetime intermediate between the two pristine materials. Density functional theory calculations suggest that this is due to orbital mixing between energetically close benzothiadiazole- and porphyrin-localized molecular orbitals, creating a mixed F8BT/porphyrin triplet state

Highly red-shifted NIR emission from a novel anthracene conjugated polymer backbone containing Pt(II) porphyrins

We present the synthesis of a novel diphenylanthracene (DPA) based semiconducting polymer.</p

Highly red-shifted NIR emission from a novel anthracene conjugated polymer backbone containing Pt(II) porphyrins

We present the synthesis of a novel diphenylanthracene (DPA) based semiconducting polymer.</p

Enhanced sub-bandgap efficiency of a solid-state organic intermediate band solar cell using triplet-triplet annihilation

© The Royal Society of Chemistry 2017. Conventional solar cells absorb photons with energy above the bandgap of the active layer while sub-bandgap photons are unharvested. One way to overcome this loss is to capture the low energy light in the triplet state of a molecule capable of undergoing triplet-triplet annihilation (TTA), which pools the energy of two triplet states into one high energy singlet state that can then be utilized. This mechanism underlies the function of an organic intermediate band solar cell (IBSC). Here, we report a solid-state organic IBSC that shows enhanced photocurrent derived from TTA that converts sub-bandgap light into charge carriers. Femtosecond resolution transient absorption spectroscopy and delayed fluorescence spectroscopy provide evidence for the triplet sensitization and upconversion mechanisms, while external quantum efficiency measurements in the presence of a broadband background light demonstrate that sub-bandgap performance enhancements are achievable in this device. The solid-state architecture introduced in this work serves as an alternative to previously demonstrated solution-based IBSCs, and is a compelling model for future research efforts in this area

A Nature-Inspired Conjugated Polymer for High Performance Transistors and Solar Cells

A novel, highly soluble chromophore for use in organic electronics based on an indigoid structure is reported. Copolymerization with thiophene affords an extremely narrow band gap polymer with a maximum absorption at ∼800 nm. The novel polymer exhibits high crystallinity and high ambipolar transport in OFET devices of 0.23 cm² V^–1 s^–1 for holes and 0.48 cm² V^–1 s^–1 for electrons. OPV device efficiencies up to 2.35% with light absorbance up to 950 nm demonstrate the potential for this novel chromophore in near-IR photovoltaics