Skip to main content

LUP Student Papers

LUND UNIVERSITY LIBRARIES

Optical Biosensing in Non-Transparent Media Using Nanowire Platforms

Alkhulaifi, Noah Abdulaziz Mohammed Sulaiman LU (2025) PHYM03 20251
Solid State Physics
Department of Physics
Abstract
Semiconductor nanowires with high refractive index have waveguiding properties that can enhance the excitation and the quantum yield of a surface-bound fluorescent molecule, and guide and directionally emit its optical signal. Prior work has shown that this allows for enhanced optical biosensing in transparent sample matrices, with advanced image analysis techniques further improving sensitivity.
An important application that has remained relatively untouched is optical biosensing in non-transparent media, an extremely relevant topic when it comes to detection in biological sample matrices without intensive sample processing. The absorbance and scattering of light that occurs in complex sample matrices due to the presence of macro- and... (More)
Semiconductor nanowires with high refractive index have waveguiding properties that can enhance the excitation and the quantum yield of a surface-bound fluorescent molecule, and guide and directionally emit its optical signal. Prior work has shown that this allows for enhanced optical biosensing in transparent sample matrices, with advanced image analysis techniques further improving sensitivity.
An important application that has remained relatively untouched is optical biosensing in non-transparent media, an extremely relevant topic when it comes to detection in biological sample matrices without intensive sample processing. The absorbance and scattering of light that occurs in complex sample matrices due to the presence of macro- and micro-molecules makes it virtually impossible to image our NW samples directly through the sample medium.
Our approach has been to use semiconductor nanowires embedded in fluorescence microscopy compatible polymer to image in non-transparent sample matrices. We achieve this by illuminating through the transparent substrate and focusing on the bottom of the nanowire tips, thereby circumventing the need to image through complex sample matrices.
The results are nanomolar optical detection of fluorescently labelled proteins in a selection of non-transparent media without sample processing and using conventional epifluorescence microscopy. The media investigated are human whole blood, a lipid emulsion (Calogen nutritional beverage) and powdered milk solution. Our results demonstrate a versatile biosensor platform that allows for sensitive nanomolar imaging in blood.. We aim to expand upon these results and focus on lowering the limit of detection and explore the possibility of single-molecule detection in human whole-blood. (Less)
Popular Abstract
Biosensing concerns itself with the detection of relevant biomolecules at low concentrations in a variety of fluids for different applications (biomarkers of disease, contaminants…) A biosensor typically consists of three components: the biomolecule acting as the analyte, the sensing element, and the ability to generate a signal when the analyte and the sensing element come into contact with each other. That being said this becomes more complicated and the general scheme may be complicated by less trivial setups that require additional input in order to extract the necessary information. Biosensing has come a long way from simple detections of glucose using cheap, portable amperometric biosensors to single-molecule tracking in real time.
... (More)
Biosensing concerns itself with the detection of relevant biomolecules at low concentrations in a variety of fluids for different applications (biomarkers of disease, contaminants…) A biosensor typically consists of three components: the biomolecule acting as the analyte, the sensing element, and the ability to generate a signal when the analyte and the sensing element come into contact with each other. That being said this becomes more complicated and the general scheme may be complicated by less trivial setups that require additional input in order to extract the necessary information. Biosensing has come a long way from simple detections of glucose using cheap, portable amperometric biosensors to single-molecule tracking in real time.

This project utilises semiconductor nanowires, a microscope and a laser to detect fluorophore-bound proteins. Our goal is to develop this nanowire-based technology such that it can be used in real-time, highly sensitive, biomedical applications providing a new tool for the biomedical field among others. The nanowires that we are using offer a high signal-to-noise ratio and have specific optical properties that lead to the enhancement of fluorescent signal and directional emission. They, along with the microscope system that we have form the “sensor”, hundreds of thousands of nano-sensors that improve our ability to make positive detections. This particular system has been proven to work in a transparent medium and we wish to extend this functionality to non-transparent media including but not limited to blood. This leap in functionality would potentially allow us to shift from looking into what is occuring at complex biological interfaces to how these interactions are mediated, how they can be influenced and for example how we can use this knowledge to develop more effective medicine. (Less)
Please use this url to cite or link to this publication:
author
Alkhulaifi, Noah Abdulaziz Mohammed Sulaiman LU
supervisor
organization
course
PHYM03 20251
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Nanowires, Biosensing, Experimental Optics, TIRF
language
English
id
9203437
date added to LUP
2025-06-23 09:41:54
date last changed
2025-06-23 09:41:54
@misc{9203437,
  abstract     = {{Semiconductor nanowires with high refractive index have waveguiding properties that can enhance the excitation and the quantum yield of a surface-bound fluorescent molecule, and guide and directionally emit its optical signal. Prior work has shown that this allows for enhanced optical biosensing in transparent sample matrices, with advanced image analysis techniques further improving sensitivity.
An important application that has remained relatively untouched is optical biosensing in non-transparent media, an extremely relevant topic when it comes to detection in biological sample matrices without intensive sample processing. The absorbance and scattering of light that occurs in complex sample matrices due to the presence of macro- and micro-molecules makes it virtually impossible to image our NW samples directly through the sample medium.
Our approach has been to use semiconductor nanowires embedded in fluorescence microscopy compatible polymer to image in non-transparent sample matrices. We achieve this by illuminating through the transparent substrate and focusing on the bottom of the nanowire tips, thereby circumventing the need to image through complex sample matrices. 
The results are nanomolar optical detection of fluorescently labelled proteins in a selection of non-transparent media without sample processing and using conventional epifluorescence microscopy. The media investigated are human whole blood, a lipid emulsion (Calogen nutritional beverage) and powdered milk solution. Our results demonstrate a versatile biosensor platform that allows for sensitive nanomolar imaging in blood.. We aim to expand upon these results and focus on lowering the limit of detection and explore the possibility of single-molecule detection in human whole-blood.}},
  author       = {{Alkhulaifi, Noah Abdulaziz Mohammed Sulaiman}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Optical Biosensing in Non-Transparent Media Using Nanowire Platforms}},
  year         = {{2025}},
}