Extended Data Fig. 6: Evaluation of NeuroString performance for serotonin sensing in the GI tract of rodents and large animals.
From: A tissue-like neurotransmitter sensor for the brain and gut
a, Setup of the colonic motility assay providing video imaging and spatiotemporal maps to analyse colonic motility of mice inserted with NeuroString ex vivo. Control is a mouse colon without anything inside the lumen. b, Representative H&E staining images showing the colon tissue of mice placed with a flexible Kapton (length 2 cm, width 800 μm, thickness 120 μm) film and a NeuroString with the same dimensions. The materials were placed in the colon of freely moving mice for 3 h before collecting the tissue. Damage to the tissue was clearly observed with flexible polyimide film implant. The H&E staining was repeated and reproduced for five mice. Open-field activity (average velocity) (c, d) and pellet output (e) over a 5-h period for mice with the colon acutely placed with a NeuroString or a flexible Kapton polyimide as control (n = 6). P-values: NeuroString (0.9689), polyimide (0.0004) in d; NeuroString (0.4895), polyimide (0.0015) in e. The dotted lines in c show 5-min trajectories of the mice. f, Photos showing NeuroString wrapped around a probe extended from one working channel of an endoscope (left) and the obtained endoscopy photo showing the NeuroString entering the colon lumen for serotonin sensing in a rat model (right). g, Representative serotonin concentration mapping in the rat colon (5 cm from the anus) collected by delivering the NeuroString into the colon lumen and slowly taking it out (error bar denotes ±standard deviation of the measurement results obtained from three channels). h, μ-CT images showing the NeuroString conformally loaded in the mouse colon. i, Representative H&E staining images showing the colon tissue of control mouse treated with saline water and colitis mouse with inflammation induced by DSS after 10 days of colitis development. The H&E staining was repeated and reproduced for five mice. j, Measured serotonin concentration in the colon tissue of control and DSS mice using enzyme-linked immunosorbent assay. P-value 0.0171. k, Layout of the NeuroString sensor for serotonin sensing in the pig colon. The sensor fabrication process is the same as that illustrated in Extended Data Fig. 1, except for the use of a large polyimide sheet (12” × 12”) as a substrate. l, Scheme and photo showing the multiple-site serotonin measurement in the intestine of a pig by NeuroString. m, Simultaneous serotonin sensing in different segments of the intestinal tract by multiple-channel NeuroString. n, o, Drug-induced luminal serotonin concentration change using fluoxetine (SSRI), MB, fluoxetine (SSRI) + MB and saline as control (n = 6 pigs). P-values: SSRI (0.5553), MB (0.3567), SSRI + MB (0.0099). P-values are calculated by paired two-tailed Student’s t-test: NS, P > 0.05; *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001.
