PMID- 31983930
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20201208
IS  - 1759-9660 (Print)
IS  - 1759-9679 (Electronic)
IS  - 1759-9660 (Linking)
VI  - 11
IP  - 45
DP  - 2019 Dec 7
TI  - A microfluidic platform integrating pressure-driven and electroosmotic-driven 
      flow with inline filters for affinity separations.
PG  - 5768-5775
LID - 10.1039/C9AY01758E [doi]
AB  - Pancreatic islets of Langerhans release glucagon to maintain blood glucose 
      levels, and release of this peptide is dysregulated in diabetes mellitus. 
      Although the importance of proper secretion of this peptide has been shown, no 
      measurement of its release at the single islet level has been reported. In 
      previous work, a non-competitive assay for glucagon was developed with a 6 pM 
      limit of detection, low enough to measure from a single islet. To incorporate 
      this method in an online assay, a microfluidic system with several distinct 
      features was developed. To maintain appropriate flow rates in the presence of the 
      high concentration of salt that was required for the assay, a piezo-actuated 
      pressure transducer with in-line flow sensors was used to drive sample flow 
      through 80 x 50 mum (width x depth) channels, while electroosmotic flow was used 
      to gate the sample away from 15 x 5 mum separation channel. Flow rates tested with 
      this system were 50 - 200 nL min(-1) with relative standard deviations (RSDs) 
      ranging from 1 - 4 %. Use of the pressure-driven flow was found to increase the 
      amount of clogs in the system, so a method to incorporate in-line filters into 
      the channels was developed. A total of 4 low resistance, in-line microfabricated 
      filters were evaluated, with all designs prolonging the operation time of the 
      microfluidic device to more than 4 hours without clogs observed. Use of this 
      system enabled highly reproducible injections (3-6% RSD). During initial 
      incorporation of the noncompetitive assay for glucagon, it was determined that 
      Joule heating was problematic and temperature measurements revealed the 
      separation channel increased to more than 50 degrees C during operation. A 3D-printed 
      manifold was used to hold a Peltier cooler in place on the microfluidic device 
      which produced a 2.6-fold improvement in the amount of the noncovalent glucagon 
      complex that was detected compared to without cooling. These features are 
      expected to be useful for not only long-term monitoring of the glucagon release 
      from islets of Langerhans, but has the potential to be applied to a number of 
      other microfluidic separation-based assays as well.
FAU - Leng, Weijia
AU  - Leng W
AD  - Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan 
      Way, Dittmer Building, Tallahassee, FL 32306, USA.
FAU - Evans, Kimberly
AU  - Evans K
AD  - Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan 
      Way, Dittmer Building, Tallahassee, FL 32306, USA.
FAU - Roper, Michael G
AU  - Roper MG
AD  - Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan 
      Way, Dittmer Building, Tallahassee, FL 32306, USA.
LA  - eng
GR  - R01 DK080714/DK/NIDDK NIH HHS/United States
GR  - UC4 DK116283/DK/NIDDK NIH HHS/United States
PT  - Journal Article
DEP - 20191029
PL  - England
TA  - Anal Methods
JT  - Analytical methods : advancing methods and applications
JID - 101519733
PMC - PMC6980329
MID - NIHMS1063322
COIS- Conflicts of interest There are no conflicts to declare.
EDAT- 2020/01/28 06:00
MHDA- 2020/01/28 06:01
PMCR- 2020/12/07
CRDT- 2020/01/28 06:00
PHST- 2020/01/28 06:00 [entrez]
PHST- 2020/01/28 06:00 [pubmed]
PHST- 2020/01/28 06:01 [medline]
PHST- 2020/12/07 00:00 [pmc-release]
AID - 10.1039/C9AY01758E [doi]
PST - ppublish
SO  - Anal Methods. 2019 Dec 7;11(45):5768-5775. doi: 10.1039/C9AY01758E. Epub 2019 Oct 
      29.