Moving towards in pouch diagnostics for ostomy patients: exploiting the versatility of laser induced graphene sensors.

The development of a 3D printed sensor for direct incorporation within stoma pouches is described. Laser induced graphene scribed on either side of polyimide film served as the basis of a 2 electrode configuration that could be integrated within a disposable pouch sensor for the periodic monitoring of ileostomy fluid pH. The graphene sensors were characterised using electron microscopy, Raman spectroscopy, DekTak profilometry with the electrochemical properties investigated using both cyclic and square wave voltammetry. Adsorbed riboflavin was employed as a biocompatible redox probe for the voltammetric measurement of pH. The variation in peak position with pH was found to be linear over pH 3-8 with a sub Nernstian response (43 mV/pH). The adsorbed probe was found to be reversible and exhibited minimal leaching through repeated scanning. The performance of the system was assessed in a heterogeneous bacterial fermentation mixture simulating ileostomy fluid with the pH recorded before and after 96 h incubation. The peak profile in the bacterial medium provided an unambiguous signal free from interference with the calculated pH before and after incubation (pH 5.3 to 3.66) in good agreement with that obtained with commercial pH probes. Supplementary Information: The online version contains supplementary material available at 10.1007/s10853-023-08881-x.

Lasered Graphene Microheaters Modified with Phase-Change Composites: New Approach to Smart Patch Drug Delivery.

The combination of paraffin wax and O,O'-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol was used as a phase-change material (PCM) for the controlled delivery of curcumin. The PCM was combined with a graphene-based heater derived from the laser scribing of polyimide film. This assembly provides a new approach to a smart patch through which release can be electronically controlled, allowing repetitive dosing. Rather than relying on passive diffusion, delivery is induced and terminated through the controlled heating of the PCM with transfer only occurring when the PCM transitions from solid to liquid. The material properties of the device and release characteristics of the strategy under repetitive dosing are critically assessed. The delivery yield of curcumin was found to be 3.5 µg (4.5 µg/cm2) per 3 min thermal cycle.

Vascular access for hemodialysis: thrills and thrombosis.

Hemodialysis is a life saving treatment for Americans with end stage renal disease. In the last decade, liberal selection of patients treated by hemodialysis has resulted in patients who are substantially older, diabetics, who have higher co-morbidities including extensive atherosclerotic vascular disease. Many of these patients start hemodialysis treatments with a synthetic graft access rather than with their own native vessels. Grafts are appropriate for patients with inadequate vessels for construction of an arterio-venous (A-V) fistulas. The National Kidney Foundation published the Dialysis Outcome Quality Initiative (DOQI) guidelines in 1997, a set of evidenced based guidelines regarding the optimal management of vascular access. One important guideline had been to increase the number of patient dialyzing with Arterio-Venous (A-V) fistulas rather than A-V grafts which are prone to frequent stenosis, thrombosis, and thus are more costly and labor intensive. The prevalence of patient dialyzing with fistulas depends on several factors; timing of the referral, anatomy and adequacy of the patients vessels, type of fistula placed, fistula maturation, minimal accepted dialysis blood flow and patency of the fistula. The management of a vascular access for hemodialysis is a challenging area of practice for those who care for the hemodialysis patient population. The multidisciplinary approach to management of patients with hemodialysis access includes support, education, collaboration and ongoing communication with the multidisciplinary team, patients, and their family members.