Malignant brain tumors are cancerous growth in the brain with the possibility of spreading to other parts of the central nervous system (CNS). Brain tumors are highly invasive and have devastating consequences, poor prognosis, and low survival rates.
Recently, the noninvasive near-infrared fluorescence and photoacoustic imaging techniques have demonstrated a bright scope in brain tumor diagnosis with high spatiotemporal resolution, large penetration depth, and good sensitivity. Hence, these imaging techniques have been used to guide real-time brain tumor therapy with high efficiency and accuracy.
An article published in the journal Advanced Drug Delivery Reviews presented a summary of state-of-art near-infrared contrast agents (CAs) and optical imaging-guided therapies for brain tumor imaging. Finally, the opportunities and challenges involved in the use of CAs and nanotheranostics for future clinical translation were discussed.
Near-Infrared Fluorescence Imaging of Brain Tumors
The brain tumor is an intracranial neoplasm in the brain or the central spinal canal. An abnormal and uncontrolled cell division, usually in the brain, involving neurons or glial cells or occasionally in the lymphatic tissue, blood vessels, and others, is the main leading cause of the formation of primary brain tumors. The majority of the brain tumors in adults are secondary or metastatic tumors, that is, cancers primarily located in other organs and may spread to the brain and create brain tumors.
Diagnosis of brain tumors is the critical step for effective curing of the disease, and it vividly relies on the advancements in molecular imaging technology. Although various imaging modalities, including magnetic resonance imaging (MRI), positron emission tomography (PET) imaging, and computed tomography (CT) imaging were investigated for the detection of brain tumors, these modalities possess several limitations.
In this regard, fluorescence imaging is a method that relies on fluorescence, absorption, bioluminescence, and reflectance resulting from various fluorescent nanomaterials used for visualizing the brain microstructures and monitoring the tumor progression.
Nevertheless, the effectiveness and safety of fluorescence imaging, using visible light for fluorescence imaging, displayed limited penetration of the light and resulted in decreased light-tissue interactions. Light in the near-infrared range (wavelength: 650–900 nanometers) has several advantages over visible-range light, including deeper tissue penetration due to less absorption by hemoglobin and water and less autofluorescence from surrounding tissues. Consequently, a new scope has emerged for near-infrared fluorescence imaging for detecting and treating brain tumors.
Near-infrared fluorescence imaging of brain tumors is a growing field for preclinical and clinical applications in clinical management due to its advantageous features, including a high spatial resolution, portability, real-time display, and detailed molecular profiling with the multiplexed use of fluorescent probes.
Similarly, near-infrared photoacoustic imaging (PAI) is a noninvasive imaging technique that involves acoustic waves as the emission source. It combines the advantages of ultrasonic and optical energies to realize biological imaging with deep tissue penetration depth. Thus, making PAI a promising diagnosis technique.
Near Infrared Optical Imaging-Guided Treatment of Brain Tumors
Near-infrared optical imaging-guided brain tumor therapy has been used in theranostics. Various therapeutic functions have been demonstrated with the assistance of near-infrared fluorescence imaging and PAI.
Despite encouraging progress, several obstacles remain in transitioning optical imaging techniques to clinical applications. As safety is the primary concern for the clinical translation of nanomedicine, nanotheranostics and nanoprobes are subjected to various surface modifications using biocompatible polymers to reduce their toxicities.
Near-infrared fluorescence imaging and PAI have vividly helped in the diagnosis of cancer. However, the presence of the skull and scalp hampers the quality of light and the imaging of brain tumors. This suggests that the second near-infrared region (NIR-II) can increase tissue penetration and depth while decreasing light scattering and enhancing the signal-to-background ratio. Consequently, deep-seated brain tumors can also be diagnosed.
CAs with excited-state intramolecular motion have good prospects for fine-tuning the balance between nonradiative and radiative decay in dual-mode near-infrared fluorescence imaging or PAI. Near-infrared fluorescence imaging CAs, including organic dyes, semiconducting polymer dots, aggregation-induced emission luminous, and inorganic (quantum dots and rare-earth nanoparticles) probes, have been investigated for the diagnosis of brain tumors.
Conclusion
Overall, multimodal optical imaging techniques can decrease misdiagnosis rates of brain tumors and provide functional and anatomical information. Moreover, theranostic agent-based imaging guidance and combination treatment can enhance the treatment outcomes of brain tumors and reduce side effects.
Furthermore, nanoparticles less than 5 nanometers in size are favorable for renal excretion and reduce toxicity during treatment. Thus, the fabrication of biodegradable nanomaterials followed by toxicity evaluations can increase the clinical success of treatment.
In the case of brain tumors, the blood-brain barrier restricts the entry of nanoagents into brain tissues. In this regard, peptides with targeting abilities and focused ultrasound (FUS) assistance can help deliver nanoagents to brain tumors for diagnosis and therapy.
New book from NanoappsMedical Inc – Molecular Manufacturing: The Future of Nanomedicine
This book explores the revolutionary potential of atomically precise manufacturing technologies to transform global healthcare, as well as practically every other sector across society. This forward-thinking volume examines how envisaged Factory@Home systems might enable the cost-effective [...]
A Virus Designed in the Lab Could Help Defeat Antibiotic Resistance
Scientists can now design bacteria-killing viruses from DNA, opening a faster path to fighting superbugs. Bacteriophages have been used as treatments for bacterial infections for more than a century. Interest in these viruses is rising [...]
Sleep Deprivation Triggers a Strange Brain Cleanup
When you don’t sleep enough, your brain may clean itself at the exact moment you need it to think. Most people recognize the sensation. After a night of inadequate sleep, staying focused becomes harder [...]
Lab-grown corticospinal neurons offer new models for ALS and spinal injuries
Researchers have developed a way to grow a highly specialized subset of brain nerve cells that are involved in motor neuron disease and damaged in spinal injuries. Their study, published today in eLife as the final [...]
Urgent warning over deadly ‘brain swelling’ virus amid fears it could spread globally
Airports across Asia have been put on high alert after India confirmed two cases of the deadly Nipah virus in the state of West Bengal over the past month. Thailand, Nepal and Vietnam are among the [...]
This Vaccine Stops Bird Flu Before It Reaches the Lungs
A new nasal spray vaccine could stop bird flu at the door — blocking infection, reducing spread, and helping head off the next pandemic. Since first appearing in the United States in 2014, H5N1 [...]
These two viruses may become the next public health threats, scientists say
Two emerging pathogens with animal origins—influenza D virus and canine coronavirus—have so far been quietly flying under the radar, but researchers warn conditions are ripe for the viruses to spread more widely among humans. [...]
COVID-19 viral fragments shown to target and kill specific immune cells
COVID-19 viral fragments shown to target and kill specific immune cells in UCLA-led study Clues about extreme cases and omicron’s effects come from a cross-disciplinary international research team New research shows that after the [...]
Smaller Than a Grain of Salt: Engineers Create the World’s Tiniest Wireless Brain Implant
A salt-grain-sized neural implant can record and transmit brain activity wirelessly for extended periods. Researchers at Cornell University, working with collaborators, have created an extremely small neural implant that can sit on a grain of [...]
Scientists Develop a New Way To See Inside the Human Body Using 3D Color Imaging
A newly developed imaging method blends ultrasound and photoacoustics to capture both tissue structure and blood-vessel function in 3D. By blending two powerful imaging methods, researchers from Caltech and USC have developed a new way to [...]
Brain waves could help paralyzed patients move again
People with spinal cord injuries often lose the ability to move their arms or legs. In many cases, the nerves in the limbs remain healthy, and the brain continues to function normally. The loss of [...]
Scientists Discover a New “Cleanup Hub” Inside the Human Brain
A newly identified lymphatic drainage pathway along the middle meningeal artery reveals how the human brain clears waste. How does the brain clear away waste? This task is handled by the brain’s lymphatic drainage [...]
New Drug Slashes Dangerous Blood Fats by Nearly 40% in First Human Trial
Scientists have found a way to fine-tune a central fat-control pathway in the liver, reducing harmful blood triglycerides while preserving beneficial cholesterol functions. When we eat, the body turns surplus calories into molecules called [...]
A Simple Brain Scan May Help Restore Movement After Paralysis
A brain cap and smart algorithms may one day help paralyzed patients turn thought into movement—no surgery required. People with spinal cord injuries often experience partial or complete loss of movement in their arms [...]
Plant Discovery Could Transform How Medicines Are Made
Scientists have uncovered an unexpected way plants make powerful chemicals, revealing hidden biological connections that could transform how medicines are discovered and produced. Plants produce protective chemicals called alkaloids as part of their natural [...]
Scientists Develop IV Therapy That Repairs the Brain After Stroke
New nanomaterial passes the blood-brain barrier to reduce damaging inflammation after the most common form of stroke. When someone experiences a stroke, doctors must quickly restore blood flow to the brain to prevent death. [...]
