Optical microneedle device enables glucose quantification in ultra-trace samples
A fluorescence-based microneedle device has achieved glucose detection in sub-nanoliter volumes of ISF, enabling highly localized and short-term biomolecule measurements.
A team at the University of Tokyo (Japan) has developed a fluorescence-based microneedle sensor able to detect D-glucose in interstitial fluid (ISF) at nanoliter volumes, demonstrating the utility of this technology as a biosensing platform.
ISF contains numerous biomolecules useful for disease diagnosis, the most notable being D-glucose for diabetes management, but collecting and analyzing ISF remains challenging. Extracting dermal ISF disrupts the pressure balance between the inside and outside of blood vessels, meaning sampling ISF requires sub-nanoliter extraction volumes or the use of in situ sensing using miniature sensors.
Microneedle devices offer a promising solution; however, conventional enzymatic measurements consume target molecules, which compromises sensing reliability, particularly in small volumes. To overcome these limitations, the team developed a poly-L-lactide (PLLA) fluorescence-based microneedle device, using D-glucose sensing to prove its functionality.
How the microneedles work
The PLLA microneedles penetrate the epidermis and dermis to reach the ISF near the blood vessels. The needles are fixed to a fluorescent probe and contain a hydrogel block at their tip. It is this hydrogel block that enables the extraction of biomolecules via diffusion, serving as the reaction space for in situ molecular sensing. Upon contact with glucose, the hydrogel reversibly binds to D-glucose and emits a fluorescent signal. The team demonstrated that the fluorescence intensity had a confirmed quantitative correlation with the amount of glucose present within the hydrogel.
You may also be interested in:
- A device that monitors health by wrapping around your finger? No sweat
- Seafood Waste Material for Wearable Biosensors
- Go with your gut: novel biosensor SENSBIT mimics the gut’s defenses
Future outlook
Optical microneedle devices using functional hydrogels at their tips enable quantitative analysis without consuming the target compound, making them an excellent method for testing ultra-micro samples. With the aim of replacing blood draws with clinical testing using ISF, this approach is expected to enhance the quality and efficiency of home healthcare.
