Lead sulfide quantum dots (PbS QDs) are a type of semiconductor nanoparticle that have unique electronic and optical properties, making them useful for a variety of applications, including sensing, imaging, and energy harvesting. Horse radish peroxidase (HRP) is an enzyme commonly used in biochemistry and molecular biology to catalyze reactions. Researchers have recently explored the use of HRP-functionalized PbS QDs for bioimaging and biosensing applications. By conjugating HRP to the surface of the PbS QDs, researchers have demonstrated improved stability, biocompatibility, and catalytic activity, making them a promising tool for a range of applications in biotechnology and medicine.

1. MONITORING
NEOVASCULARIZATION OF
MALIGNANT SOLID TUMORS
WITH HORSERADISH
PEROXIDASE-FUNCTIONALIZED
NEAR-INFRARED-II PbS
QUANTUM DOTS

2. CONTENT
BACKGROUND METHODOLOGY
OVERVIEW
RESULTS AND
DISCUSSION
CONCLUSION

3. BACKGROUND

4. Introduction
• Early detection and prompt treatment are
crucial for improving cancer survival rates
and quality of life.
• Only a handful of labels can provide the
necessary brightness and stability for
high-quality imaging of deep tissue.
• This study explores the use of PbS
quantum dots and horseradish
peroxidase (HRP-QDs) to create a
fluorescent label for real-time and high-
detail imaging of blood vessels in tumors.

5. Neovascularization
• Malignant tumors rely on new blood vessels for growth and
metastasis.
• To achieve this, they undergo vasculogenic mimicry .
• This feature occurs in different types of cancer
• Patients with vasculogenic mimicry have a zero 5-year survival
rate, while those without it have a 20% rate.
• In vivo monitoring of vasculogenic mimicry using micron-
resolution imaging can accurately and noninvasively identify
benign and malignant tumors.

6. NIR-II fluorescence imaging
• Fluorescence imaging in vivo is useful for tumor diagnosis and
treatment.
• NIR-II wavelengths (1000-1700 nm) have advantages over visible
and NIR-I (750-950 nm) wavelengths, including lower tissue
autofluorescence and deeper tissue penetration.
• NIR-II QDs are a promising tool for detecting tumors, guiding
surgeries, and predicting outcomes because they can be modified
and functionalized for biological use.

7. METHODOLOGY OVERVIEW

8. Overview
A fluorescent label for
monitoring tumor vascular
evolution was created
using PbS QDs modified
with a water-soluble
polymer and PEG.
The label was coupled with
HRP to create HRP-QDs.
In vivo experiments to show NIR-II
fluorescence imaging of tumor vessels
with micron-level spatial resolution.
Changes in tumor vessels at different
growth stages were monitored in real
time.
A quantitative system for evaluating
the blood supply pattern in the early
stage of malignant solid tumor growth
was developed.

9. RESULTS AND
DISCUSSION

10. • PbS QDs were synthesized
and characterized
• The QDs had a peak emission
wavelength of 1300 nm and a
relatively narrow fluorescence
emission peak halfwidth.
• The QDs were modified with
OPA and PEG
• Agarose gel electrophoresis
showed the successful
charge-neutralization of the
QDs.
PbS quantum dots:
synthesis and
performance
optimization

11. HRP quantum dots:
synthesis and
characterization
• The optimal ratio of PEG-QDs to
HRP was found to be 1:10.
• The HRP-QDs showed an
absorption spectrum characteristic
of oxidized TMB and a slightly
broader fluorescence spectrum than
PEG-QDs.
• The hydrated particle size increased
during HRP coupling

12. Revolutionizing
tumor imaging:
high-resolution
real-time
angiography using
HRP-QDs
• The QDs hydration size
and surface charge
regulation increased their
blood circulation time.
• Using 100 mm lens
improved the signal
intensity of tumor blood
vessels
• Blood vessel of 99.5 μm
width clearly
distinguishable.

13. • The researchers used live imaging
and examination of dissected
tissues.
• Injecting HRP-QDs into mice with
tumors through the tail vein
produced a fluorescence signal in
the tumor and positive DAB staining
of the tumor sections.
Mapping early tumor growth:
identifying blood supply
patterns for improved diagnosis
1. Dual-mode imaging of tumor vessels: in
vivo and tissue level analysis using
bifunctional HRP-QDs

14. Mapping early
tumor growth:
identifying blood
supply patterns for
improved diagnosis
• DAB staining to
determine the position
and morphology of
blood vessels
• IF to label the signature
antigen CD31 on
endothelial cells
• Hematoxylin staining
to verify the position of
2. Assessing Tumor Vascular
Evolution: Combining IHC
and IF Analyses Using HRP-
QDs

15. • The researchers made cancer
models of different sizes (2, 3, 4,
and 5 mm)
• IHC and IF imaging showed that all
blood vessels in tumors that are 2
mm in size were made through
vascular mimicry. When the tumor
grew to 3 mm, blood vessels formed
Enhancing early tumor
detection: identifying blood
supply patterns using novel
imaging techniques
1. Temporal and Spatial Analysis
of Tumor Blood Supply: In Vivo
Imaging and IHC/IF Analysis of
Tumors of Various Sizes

16. Enhancing early tumor
detection: identifying
blood supply patterns
using novel imaging
techniques
• Vascular density increased
with tumor size
• Statistical analysis found that
the total number of vessels
and the number formed by
endothelium-dependent cells
increased with tumor size.
• The proportion of vessels
formed by vasculogenic
mimicry decreased as a
function of tumor size, while
endothelium-dependent
vessels increased.
2. Quantitative Analysis of Tumor
Blood Supply: Fluorescence
Intensity and Statistical Analysis
of Vessel Density in Malignant
Solid Tumors of Various Sizes

17. CONCLUSION

18. Conclusion
• The use of HRP-QDs achieves micron-
and millisecond-resolved imaging in vivo,
enabling the visualization of living blood
vessels and accurate identification of the
types of blood vessels.
• Statistical analysis can help evaluate the
blood supply and growth of tumors.
• Malignant tumors can sometimes be
diagnosed by checking the blood supply
around the tumor in real-time.
• Blood supply during early stage of tumor
growth is mainly done by vasculogenic
mimicry. NIR-II QDs help in easy

19. THANK YOU