Biophotonics in Clinical and Biomedical Applications

What is biophotonics?

Interdisciplinary field that combines photonics and biology

What does it utilise?

Tools and techniques based on the properties of light to image, diagnose and treat living organisms

At the molecular, cellular and tissue level

Photons

Light exhibits wavelike properties

What happens when photons interact with matter?

They can be absorbed, scattered or allowed to pass through

What do tissues absorb, scatter and fluoresce?

Light

Differently based on their biochemical makeup

What can provide optic signatures from specific light wavelengths?

Haemoglobin

Water

Lipids

DNA/RNA

What can be used to selectively tag molecules of interest to study cellular processes?

Fluorescent probes can be used to selectively tag molecules

What can provide high resolution structural and functional imaging of tissues?

Microscopy

Endoscopy

OCT (Optical coherence tomography)

What does spectroscopy measure?

Absorption/scattering spectra to detect diseases like cancer through biochemical changes

Photoacoustic/thermographic Imaging

Fuses optical and ultrasound contrast for anatomical and physiological visualisation

What can photodynamic therapy be used for?

Light activated drugs to selectively destroy cancerous cells

What can low level laser therapy be used for?

Employs light to accelerate tissue repair processes

Optogenetics

Control neuronal activity with high spatiotemporal precision using light-sensitive proteins

Strengths of Fluorescence Imaging

-High sensitivity and specificity=molecular targeting with fluorescent probes

-Versatile multicolour imaging enables visualisation of multiple biological entities

Limitations of Fluorescence Imaging

-Autofluorescence from intrinsic molecules can limit specificity

-Photobleaching limits time-lapse imaging

Strengths of Raman Spectroscopy

-Provides fingerprint molecular vibrational information without labels

-Can distinguish tissues based on molecular composition

Limitations of Raman Spectroscopy

-Weak Raman signals require long acquisition times

-Strong fluorescence interference degrades spectral features

Strengths of Optical Coherences Tomography (OCT)

-Non-invasive, label-free, high-resolution 3D imaging of inner tissue/organs

-Can quantify subtle morphological and physiological changes

Limitations of Optical Coherences Tomography (OCT)

-Small penetration depth limits accessibility to deeper tissues

-Backscattering from different depths degrade image contrast

Strengths of Photoacoustic imaging

-Combines high optical contrast and ultrasound resolution for functional imaging

-Sensitive to optical absorption providing molecular/cellular specificity

Limitations of Photoacoustic Imaging

-Diffuse optical scattering limits resolution and penetration depth

-Artefacts from acoustic heterogeneities and phase aberrations

What does Optical biopsy via fluorescence, Raman and IR spectroscopies detect?

Disease biomarkers in tissues for cancer, atherosclerosis etc diagnosis

What does fiberoptic endomicroscopy facilitate?

In vivo histopathology of internal surfaces during clinical examinations

What does OCT (Optical coherence tomography) aid?

High resolution imaging of retina, skin lesions for disease screening and longitudinal studies

What does photoacoustic tomography visualise?

Vasculature

Monitors angiogenesis

Treatment response non-invasively

What can fluorescence imaging help guide?

Procedures to visualise tumours, sentinel lymph nodes with molecular specificity intraoperatively

What is the role Raman imaging in cancer?

Identifies margins for complete tumour resection in real time

What does photoacoustic monitor in terms of treatment?

Evaluate tumour oxygenation, hemodynamic during photodynamic/radiation therapies

How does Raman spectroscopy assess treatment?

Induced biochemical changes in tissues

What can spectroscopic techniques detect?

Pre-malignant changes

Increases chance of effective interventions

What does quantifying structural changes from fluorescence/OCT images detect?

Angiogenesis

Calcification

Alterations in cellularity

What does analysis of spectroscopic peaks/bands correspond to?

Biomolecules to identify compositional changes

Can apply multvariate tools for sample classification and disease prediction

What do fluorescence/Raman profiles provide?

Molecular fingerprints to detect tumour metabolites and assess redox states

Biomolecular analysis of the extracellular matrix

Remodelling of extracellular matrix

Drug distribution at subcellular scales

What can multimodal imaging/spectroscopy capture?

Physiological disturbance to understand molecular underpinnings of disease

Reveal altered metabolic pathways, protein conformational changes associated with disease progression

What does serial imaging track?

Therapeutic responses by quantifying changes in vasculature, tissue oxygenation during therapies

What can be used to identify compositional/structural alterations induced by drugs?

Spectroscopy

Ethical use of biophotonics tools in clinical practice

Adhere to principles of beneficence, non-maleficience, autonomy and informed consent

Safety considerations of biophotonics

Comply with laser/radiation safety standards to protect patients and personnel

Implement optical dose limits and diagnostic reference levels

How can biophotonics be secure and confidential?

De-identify patient data and restrict access to authorised individuals

Encrypt electronic health records and use security protocols

Addressing inequitable access

Consider socioeconomic disparities in availability of advanced technologies

Promote accessibility in underserved regions via point of care devices

Regulatory approvals

FDA/EMA by demonstrating safety, efficacy for intended use

Perform rigorous validation and clinical trials

Informed consent and biophotonics

Provide opt-in choice regarding data sharing for research purposes

Disclose risks, benefits and alternatives to proposed interventions