Self-assembled porous polymer films for improved oxygen sensing

Absolute oxygen sensors based on quenching of phosphorescence have been the subject of numerous studies for the monitoring of biological environments. Here, we used simple fabrication techniques with readily available polymers to obtain high performance phosphorescent films. Specifically, evaporation-based phase separation and the breath figure technique were used to induce porosity. The pore sizes ranged from ∼ 37 nm to ∼ 141µm while the maximum average porosity achieved was ∼ 74%. The oxygen sensing properties were evaluated via a standarised calibration procedure with an optoelectronic setup in both transmission and reflection based configurations. When comparing non-porous and porous films, the highest improvements achieved were a factor of ∼ 7.9 in dynamic range and ∼ 7.3 in maximum sensitivity, followed by an improved linearity with a half-sensitivity point at 43% O2 V/V. Also, the recovery time was reduced by an order of magnitude in the high porosity film and all samples prepared were not affected by variations in the humidity of the surrounding environment. Despite the use of common polymers, the fabrication techniques employed led to the significant enhancement of oxygen sensing properties and elucidated the relation between porous film morphologies and sensing performance

Label-free Electrochemical Immunosensor for Monitoring Kidney Transplant Rejection with Electroactive Antibiofouling Hydrogel

Diagnosing acute rejection of kidney transplant remains challenging as standard practice relies on monitoring serum creatinine levels and performing biopsies. The former lacks sensitivity, while the latter is invasive. Monitoring Chemokine IP-10 (or CXCL10) in patient samples has shown promising results in addressing these bottlenecks but is measured with expensive and time-consuming protocols such as enzyme-linked immunosorbent assay (ELISA). This does not allow for an individualized approach. The present work describes the development of a novel screen-printed electrode-based electrochemical biosensor for IP-10 detection using an electroactive anti-biofouling hydrogel. The electrode coating is based on glutaraldehyde (GA)-crosslinked 3D nanostructured bovine serum albumin (BSA) hydrogel, whose pores are filled with a highly conductive Ti3C2Tx MXene. The formulation is water-based and avoids the use of toxic solvents. The crosslinking mechanism, anti-biofouling characteristics, and electroactivity were characterized by UV-VIS spectroscopy, contact angle measurement, and cyclic voltammetry tests, respectively. The antibody-functionalized MXene/BSA/GA nanocomposite-based sensor allows the detection of IP-10 spiked in human serum by achieving an LOD of 3.3 pg/ml with a linear range across 1-200 pg/ml and a response time of 30 min. The study paves the way toward developing a highly specific multiplexed chemokine profiling platform for point-of-care diagnostics applications to monitor kidney transplant rejection

Nonwoven fiber meshes for oxygen sensing

Accurate oxygen sensing and cost-effective fabrication are crucial for the adoption of wearable devices inside and outside the clinical setting. Here we introduce a simple strategy to create nonwoven polymeric fibrous mats for a notable contribution towards addressing this need. Although morphological manipulation of polymers for cell culture proliferation is commonplace, especially in the field of regenerative medicine, non-woven structures have not been used for oxygen sensing. We used an airbrush spraying, i.e. solution blowing, to obtain nonwoven fiber meshes embedded with a phosphorescent dye. The fibers serve as a polymer host for the phosphorescent dye and are shown to be non-cytotoxic. Different composite fibrous meshes were prepared and favorable mechanical and oxygen-sensing properties were demonstrated. A Young's modulus of 9.8 MPa was achieved and the maximum oxygen sensitivity improved by a factor of ∼2.9 compared to simple drop cast film. The fibers were also coated with silicone rubbers to produce mechanically robust sensing films. This reduced the sensing performance but improved flexibility and mechanical properties. Lastly, we are able to capture oxygen concentration maps via colorimetry using a smartphone camera, which should offer unique advantages in wider usage. Overall, the introduced composite fiber meshes show a potential to significantly improve cell cultures and healthcare monitoring via absolute oxygen sensing

Advancing optoelectronic oxygen sensing with phosphorescent films through system configuration and morphology control

The research presented in this thesis focuses on the advancement of optoelectronic oxygen sensing with the vision of medical translation and commercialisation. The motivation stems from medical applications and the physical principles of operation rely on quenching of phosphorescence. The methodology followed is based on optoelectronic instrumentation and off-the-shelf components. The phosphorescent dye PtOEP is encapsulated in polymer matrices and inexpensive fabrication techniques are applied for morphology control. First, optimal windows of performance are identified through parametric variation of configuration and signal variables with the aim of maximizing output signal to noise ratio. Results showed the existence of favourable positioning of optical components and specific input signal characteristics, leading to an improvement of up to ∼ 3.3 in output dynamic range. By extension, readily available polymers in tandem with simple fabrication techniques are employed to enhance the sensitivity of oxygen indicators by inducing porosity. As a result, a ∼ 7 fold increase in sensitivity was achieved. Additionally, an oxygen sensing and surface morphology analysis showed that the desirable characteristics depend on the type of setup (reflection or transmission based) and that the Breath Figure technique is preferable. Finally, spray drying is used towards the creation of microfibers embedded with the oxygen sensitive dye with the purpose of cell culture monitoring and a simultaneous mammalian cell proliferation. Their potential use for wearable applications via coating with polymer rubbers was also proposed due to the improved mechanical properties, with an elongation of up to ∼ 10 demonstrated. In conclusion, it was shown that the effective use of widely available materials in conjunction with simple fabrication techniques lead to significant improvements in optoelectronic oxygen sensing and consequently aid in its future commercial adoption

Successful Thrombectomy Improves Functional Outcome in Tandem Occlusions with a Large Ischemic Core

International audienceBackground: Emergent stenting in tandem occlusions and mechanical thrombectomy (MT) of acute ischemic stroke related to large vessel occlusion (LVO-AIS) with a large core are tested independently. We aim to assess the impact of reperfusion with MT in patients with LVO-AIS with a large core and a tandem occlusion and to compare the safety of reperfusion between large core with tandem and nontandem occlusions in current practice. Methods: We analyzed data of all consecutive patients included in the prospective Endovascular Treatment in Ischemic Stroke Registry in France between January 2015 and March 2023 who presented with a pretreatment ASPECTS (Alberta Stroke Program Early CT Score) of 0–5 and angiographically proven tandem occlusion. The primary end point was a favorable outcome defined by a modified Rankin Scale (mRS) score of 0–3 at 90 days. Results: Among 262 included patients with a tandem occlusion and ASPECTS 0–5, 203 patients (77.5%) had a successful reperfusion (modified Thrombolysis in Cerebral Infarction grade 2b-3). Reperfused patients had a favorable shift in the overall mRS score distribution (adjusted odds ratio [aOR], 1.57 [1.22–2.03]; P < 0.001), higher rates of mRS score 0–3 (aOR, 7.03 [2.60–19.01]; P < 0.001) and mRS score 0–2 at 90 days (aOR, 3.85 [1.39–10.68]; P = 0.009) compared with nonreperfused. There was a trend between the occurrence of successful reperfusion and a decreased rate of symptomatic intracranial hemorrhage (aOR, 0.5 [0.22–1.13]; P = 0.096). Similar safety outcomes were observed after large core reperfusion in tandem and nontandem occlusions. Conclusions: Successful reperfusion was associated with a higher rate of favorable outcome in large core LVO-AIS with a tandem occlusion, with a safety profile similar to nontandem occlusion