Boronic acid fluorophores for saccharide sensing

1. Boronic Acid Fluorophores for
Saccharide Sensing
Danielle Bruen, Colm Delaney, Larisa Florea* and Dermot Diamond
Insight Centre for Data Analytics, National Centre for Sensor Research
(NCSR), School of Chemical Sciences, DCU.
8th Conference on Analytical Science (CASi), Ireland

2. Overview
• Background
• Diabetes – Side Effects
• Monitoring Devices
• Project Goal
• Boronic Acids (BAs) for Sugars Recognition
2
• Sensing Mechanism
• Fluorescence Results
• Future Work
• Conclusions

3. Importance of Saccharide Sensing
Stroke
Blindness
Heart Attack
Kidney Damage
Peripheral Nerve Damage
Difficultly Passing Urine
Excessive Thirst
Foot
Ulcers
Weight Gain
• Diabetes and the consequential side effects
• Monitoring glucose levels to prolong life expectancy
• Currently no noninvasive, continuous monitoring systems available
• Demonstrates a need for real-time, non-invasive monitoring
3

4. 4
Current Monitoring Methods
Implanted Devices Finger Pricking Method
Advantages:
• Real-time monitoring
• Continuous
• Coupled to insulin pump
• Elimates injections via syringe
Disadvantages:
• Invasive
Advantages:
• Minimally Invasive
Disadvantages
• Not continuous
• Insulin injections required
• Miss episodes of hyper- and
hypoglycaemia
https://www.accu-chek.co.uk/gb/products/

5. 5
Contact Lenses – The Answer!
Electrochemical sensor in a wearable platform
Continuous
Non-Invasive
Diabetics require some
form of corrective vision
Battery Powered
Interference from
Electroactive Species in
Ocular fluid
Use of Enzymes
H. Yao, et al, Biosensors and Bioelectronics, 2011, 26, 3290-3296

6. Realistically....Not a Real Working Device
6
H. Yao, et al, Biosensors and Bioelectronics, 2011, 26, 3290-3296
• Attached to a BASi Epsilon- EC Potentiostat +400 mV
• Sensing platform proposes glucose monitoring between 0.5-50 mM
• Ocular glucose range is 0.05-0.5 mM and up to 5 mM in diabetics
• Major shortcomings to meet immediate expectations

7. The Solution!
7
0.8
0.5
0.2
0.05
0.1
0.3
0.4
0.6
0.7
0.9
1
5
mM

8. Boronic Acids (BAs) and Sugars
8

9. (i) Addition of OH- ions/glucose
(ii) Addition of water/removal of glucose
Fluorescent Non-Fluorescent
Charge Neutralisation-Stabilisation Interaction
9
(i)
(ii)
-

10. (i) Anhydrous dimethylformamide, N2, 80 0C for 48h.
Successful synthesis of novel BA sensors were confirmed by 1H NMR.
Synthesis of COOHBA Sensors
10

11. 0
1000
2000
3000
4000
5000
6000
7000
300 400 500 600
FluorescenceIntensity(F.U.)
Wavelength (nm)
ex
em
Fluorescence Results
m-COOHBA 0.5 mM in pH 7.4 phosphate buffer;
Excitation 390 nm; Emission 465 nm
o-COOHBA 0.5 mM in pH 7.4 phosphate buffer;
Excitation 380 nm; Emission 485 nm
11
1500
2500
3500
4500
5500
6500
7500
0 5 10 15 20 25 30 35 40 45 50
FluorescenecIntensity(F.U.)
Glucose Concentration (mM)
1500
3500
5500
7500
0 2 4 6 8 10
0
2000
4000
6000
8000
300 350 400 450 500 550 600 650
FluorescenceIntensity(F.U.)
Wavelength (nm)
ex
em
4500
5500
6500
7500
8500
9500
0 5 10 15 20 25 30 35 40 45 50
FluorescenecIntensity(F.U.)
Glucose Concentration (mM)
4500
6500
8500
0 2 4 6 8 10
78% 40%

12. 12
Glucose response for m-COOHBA and o-COOHBA (0.5 mM) in different pH buffer
solutions ranging from pH 5-11.
0
0.2
0.4
0.6
0.8
1
1.2
0 1 2 3 4 5 6 7 8 9 10
F/F0
Glucose Concentration (mM)
pH 5.3
pH 7.4
pH 11.8
0.5
0.7
0.9
1.1
0 1 2 3 4 5
F/F0
Glucose Concentration (mM)
pH 6.3
pH 7.4
pH 11.8
pKa Investigation – Glucose Sensing pH Range

13. • Novel BAs are capable of glucose sensing
• Suitable for ocular glucose sensing
• -COOH substituent for desired anchoring possibilities
Conclusions and Future Work
• Immobilisation of the sensors on to a lens-like platform
13
Conclusions
Future Work
Decreasing
Fluorescence
Intensity
Glucose
pKa 9
Fluorescent
pKa 6
Non-Fluorescent

14. • National Centre for Sensor
Research
• Science Foundation Ireland &
INSIGHT Centre
(grant no. SFI/12/RC/2289)
• Enterprise Ireland
• EU Projects: NAPES,
CommonSense, Aquawarn,
MASK-IRSES, OrgBio
Thanks to...
• All members of my research group, in particular Dr. Larisa
Florea, Dr. Colm Delaney and Prof. Dermot Diamond
Thank you for your attention!

15. 15
PDMS Lens Fabrication

16. 16
Functionalised PDMS Lens Fluorescence Studies
Glucose Concentration
0 mM
5 mM
Glucose Concentration
2 mM
5 mM