Ms. Natalia Demidova Profile

Natalia Demidova

Undergraduate Student in Physics, Mathematics at Univ of Toronto at Mississauga

SPIE Involvement:

Author

Area of Expertise:

OCT , Oncology , Optics

Publications (5)

Proceedings Article | 13 March 2024 Presentation

Comparison of the effectiveness of two different light spectra in 5-ALA-based antimicrobial photodynamic therapy of orthopaedic implant-relevant biofilms

Logan Bateman, Valentin Demidov, Natalia Demidova, Jason Gunn, Scott Sottosanti, Eric Henderson, Ida Gitajn, Jonathan Elliot

Proceedings Volume PC12822, PC128220G (2024) https://doi.org/10.1117/12.3003128

KEYWORDS: Biofilms, Photodynamic therapy, Light sources, Biomass, Visible radiation, Titanium, Tissues, Surgery, Oxygen, Optical coherence tomography

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Proceedings Article | 13 March 2024 Presentation

Tracking viable and dead cell clusters in melanoma after FLASH and conventional radiotherapy with optical coherence tomography

Natalia Demidova, Jason Gunn, Jonathan Elliot, Alex Vitkin, Valentin Demidov

Proceedings Volume PC12856, PC1285602 (2024) https://doi.org/10.1117/12.3003490

KEYWORDS: Skin, Radiotherapy, Optical coherence tomography, Melanoma, Tumors, Tissues, Optical tracking, Windows, Vacuum chambers, In vivo imaging

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Proceedings Article | 13 March 2024 Presentation + Paper

Portable red-blue light source for antimicrobial photodynamic therapy of orthopaedic implant biofilms

V. Demidov, J. Sottosanti, N. Demidova, L. Bateman, O. Jackson, P. Craig, D. Hazem, J. Gunn, I. Gitajn, J. Elliott

Proceedings Volume 12822, 1282208 (2024) https://doi.org/10.1117/12.3000416

KEYWORDS: Biofilms, Light sources, Optical coherence tomography, Bioluminescence, Light emitting diodes, Microfluidics, Titanium, Photodynamic therapy, Contamination, Tissues

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Well-organized ecosystems of bacteria colonize orthopaedic devices causing biofilm infections that are notoriously difficult to manage. Biofilms typically exhibit increased resistance to antibiotics leading to treatment failure, and tools for eradicating biofilms that do not increase antibiotic resistance are greatly needed. Antimicrobial photodynamic therapy (aPDT) is a promising form of treatment to combat clinically relevant biofilms. Exogenous provision of 5-aminolevulinic acid (5-ALA) to biofilm-forming clinical strains of E. coli, E. faecalis and S. aureus was recently shown by several research groups to result in the accumulation of sufficient quantities of endogenous photosensitizers porphyrins (protoporphyrin IX, coproporphyrin III and others), via the heme biosynthetic pathway, to produce a significant phototoxic effect when exposed to activating light. For clinical translation of this extremely promising approach, here we develop a portable light source for 5-ALA-based aPDT of orthopaedic implant biofilms, spectrally shaped for optimal porphyrin light absorption at wavelengths range approved by FDA for clinical use. After phantom calibration, we tested it on E.coli-E.faecalis biofilms grown in soft lithography-fabricated microfluidic chips and on methicillin-resistant S. aureus (MRSA) biofilms grown on titanium and stainless steel orthopaedic hardware in custom-designed macrofluidic devices. Successful in-vitro experiments allowed us to conduct a proof-of-concept validation study in a preclinical rat model of MRSA-contaminated open fracture. Following tibia fracture and two hours of wound infection development, a one hour incubation with 20% 5-ALA and treatment with either 90J/cm² or three fractions of 30J/cm² light doses demonstrated 94% and 99% overall reduction of MRSA, respectively, while the temperature of the tissue remained <39°C, below the threshold for thermal damage. The encouraging results suggest further preclinical testing of the developed light source for optimization of aPDT regimen and 5-ALA concentration to reduce the risk of long-term side effects in animal models of contaminated trauma surgery.

Proceedings Article | 13 March 2024 Presentation + Paper

Quantification of methicillin-resistant S. aureus (MRSA) biofilm formation on orthopedic implants using bioluminescence imaging

Olivia Jackson, P. Lucas Craig, Dana Hazem, Natalia Demidova, Jason Gunn, J. Scott Sottosanti, Jonathan Thomas Elliott, Valentin Demidov, I. Leah Gitajn

Proceedings Volume 12822, 1282205 (2024) https://doi.org/10.1117/12.3001766

KEYWORDS: Bioluminescence, Biofilms, Bacteria, Titanium, Stainless steel, Standards development, In vitro testing, Microfluidics, Plating, In vivo imaging

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Proceedings Article | 13 March 2024 Presentation + Paper

Optical coherence tomography-based detection of orthopaedic implant biofilms formed by Methicillin-resistant S.aureus (MRSA)

V. Demidov, N. Demidova, D. Hazem, P. Craig, J. Gunn, O. Jackson, I. Gitajn, I. Vitkin, J. Elliott

Proceedings Volume 12822, 1282206 (2024) https://doi.org/10.1117/12.3001786

KEYWORDS: Biofilms, Optical coherence tomography, Metals, Histograms, Biological research, Bacteria, Scanning electron microscopy, Bioluminescence, Surgery, 3D image processing

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