New imaging agents were developed by physicians to detect cancer with better specificity and sensitivity. Further, they have the potential to significantly improve patient outcomes. It could offer enhanced premature cancer cells detection during routine screening and help the surgeons to identify tumor margins for surgical resection.
Figure 1. In vivo visualization of 200 nm G8-liposomes imaged following intravenous injection [1]. Notice the bright accumulation and homogenous appearance of liposomes encapsulated with G8 dye (green). The vasculature region depicted here is of the mouse ear where real time flow video was taken at 30 fps. Scale bar represents 50 μm.
Recently, Helen R. Salinas et al., has evaluated the optical properties from a colorful class of pigments and dyes that humans routinely encounter [1]. These selective dyes and pigments are approved by Food and Drug Administration (FDA) which have utilized for the coloring of foods, drugs, and cosmetics.
The authors have characterized various properties such as absorption, fluorescence and Raman scattering in the hopes of identifying a new group of dyes that offer exceptional imaging contrast.
Further, they found that some of these coloring agents, coined as “optical inks”, that exhibits a multitude of useful optical properties, outperforming some of the clinically approved imaging dyes on the market. Particularly, the two best performing optical inks which they found are as GREEN 8 and ORANGE 16, these were further incorporated into liposomal nanoparticles to assess their tumor targeting and optical imaging potential.
They also developed; these coloring agents could play a significant role in the clinical setting.
Mouse xenograft models of cervical, colorectal and lymphoma tumors were used to evaluate the recently developed nano-based imaging contrast agents.
New diagnostic imaging techniques are developing with a increased sensitivity to cancer that can allow for improved patient outcomes and earlier medical intervention.
Contrast agents are capable of actively targeting tumor cells or passively extravasating into the tumor space, making it easier for clinicians to differentiate diseased from normal tissue.
Generally, there are many commercially available fluorescence image guidance tools that already exist in clinical use [2]. One of the novel technologies is photoacoustic imaging technology that largely overcomes the depth and resolution limits of optical imaging by utilizing a sound wave detection scheme.
The FDA raises legal concerns about the efficacy and safety of new contrast imaging agents, it is importantly used in screening and diagnosis. Thus, it needs biodegradable contrast agents that exhibit lower toxicity with enhanced imaging sensitivity and tumor specificity. Therefore, the authors has decided to investigate the optical properties of the coloring agents, that people have routinely encountered over the centuries and in today’s society.
Generally, they demonstrated that these food, drug, and cosmetic dyes and tattoo ink pigments (all FDA approved) have underutilized biomedical imaging potential and should also be investigated for diagnostic imaging applications.
Identification of the dyes/pigments with the best fluorescence potential, and their quantum yield and fluorescence efficiency by optical measurements, is useful to identify the best fluorescence imaging contrast candidates.
Many researchers have demonstrated the effectiveness of visible dyes for image guidance during surgical resection of tumors [3].
Further, they have fabricated a batch of optical ink liposomes by encapsulating one of the FDA-approved dyes (G8) used in drugs and cosmetics into liposomes. These were extruded to a diameter of 200 nm and injected intravenously into a set of mice bearing the tumor xenografts. The mice were imaged using a small animal in vivo fluorescent imaging system 4 h post-injection. Tumor targeting was likely achieved via passive extravasation of the liposomes through the tumor’s leaky vasculature. Nanoparticles exhibit enhanced retention and permeability properties that make them ideal for passively accumulating into tumors. Since the liposomes were encapsulating G8 and bright fluorescent signal was easily captured by fluorescence imaging instrument.
Further, the studies of different nano size, have demonstrated the smaller nanoparticles (180 nm) with greater extravasation potential into the tumor space and thus better potential to highlight tumor margins.
Many groups have reported the shape, size and the surface properties of a nanoparticle, will influence all these and their targeting efficiency, clearance rate and extravasation potential into tumors.
These studies have further investigated on the multiphoton intravital imaging potential method and could be a powerful tool for determining the important physiological characteristics like nanoparticle circulation half-life, real-time extravasation potential and nanoparticle immune interactions of various nanoparticles types in different tumor models.
This study helps to use in real clinical treatments which could be used to sensitively detect these multi-modal nanoparticles and effectively provide with a molecular map of the tumor in real time for the physicians.
Our SNB team have interested to enhance viewer’s knowledge in a colorful approach towards developing a new nano-based imaging contrast agents for improved cancer detection. This study clearly demonstrated that the colorful organic dyes and the pigments used in tattoo inks that we daily use foods, toiletries, and cosmetics contain a multitude of excellent optical properties. Interesting experience in spectral studies like Absorption, fluorescence and Raman scattering properties have major potential to provide imaging contrast to physicians to detect better and localize cancer earlier during routine screening and/or in the operating room to help and guide the tumor resection. This is an important step towards their clinical translation for diagnostic imaging, and if further developed, could lead to better patient care as well as the improved clinical outcomes with effective results.
References
- H. R. Salinas, et al., Biomater Sci., (2020) DOI: 10.1039/d0bm01099e.
- H. J. M. Handgraaf, et al., Gynecol. Oncol., 135 (2014) 606–613.
- C. Cavallo, et al., J. Neurosurg. Sci., 62 (2018) 690–703.
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