Optical Nanosensor for Intracellular and Intracranial Detection of Amyloid-Beta

Strategies for measuring concentrations and forms of amyloid-β peptides

Alzheimer's disease (AD) is affecting more and more people worldwide without the effective treatment, while the existed pathological mechanism has been confirmed barely useful in the treatment. Amyloid-β peptide (Aβ), a main component of senile plaque, is regarded as the most promising target in AD treatment. Aβ clearance from AD brain seems to be a reliably therapeutic strategy, as the two exited drugs, GV-971 and aducanumab, are both developed based on it. However, doubt still exists. To exhaustive expound on the pathological mechanism of Aβ, rigorous analyses on the concentrations and aggregation forms are essential. Thus, it is attracting broad attention these years. However, most of the sensors have not been used in pathological studies, as the lack of the bridge between analytical chemist and pathologists. In this review, we made a brief introduce on Aβ-related pathological mechanism included in β-amyloid hypothesis to elucidate the detection conditions of sensor methods. Furthermore, a summary of the sensor methods was made, which were based on Aβ concentrations and form detections that have been developed in the past 10 years. As the greatest number of the sensors were built on fluorescent spectroscopy, electrochemistry, and Roman spectroscopy, detailed elucidation on them was made. Notably, the aggregation process is another important factor in revealing the progress of AD and developing the treatment methods, so the sensors on monitoring Aβ aggregation processes were also summarized.

Recent advances of biocompatible optical nanobiosensors in liquid biopsy: towards early non-invasive diagnosis

Liquid biopsy is a non-invasive diagnostic method that can reduce the risk of complications and offers exceptional benefits in the dynamic monitoring and acquisition of heterogeneous cell population information. Optical nanomaterials with excellent light absorption, luminescence, and photoelectrochemical properties have accelerated the development of liquid biopsy technologies. Owing to the unique size effect of optical nanomaterials, their improved optical properties enable them to exhibit good sensitivity and specificity for mitigating signal interference from various molecules in body fluids. Nanomaterials with biocompatible and optical sensing properties play a crucial role in advancing the maturity and diversification of liquid biopsy technologies. This article offers a comprehensive review of recent advanced liquid biopsy technologies that utilize novel biocompatible optical nanomaterials, including fluorescence, colorimetric, photoelectrochemical, and Raman broad-spectrum-based biosensors. We focused on liquid biopsy for the most significant early biomarkers in clinical medicine, and specifically reviewed reports on the effectiveness of optical nanosensing technology in the detection of real patient samples, which may provide basic evidence for the transition of optical nanosensing technology from engineering design to clinical practice. Furthermore, we introduced the integration of optical nanosensing-based liquid biopsy with modern devices, such as smartphones, to demonstrate the potential of the technology in portable clinical diagnosis.

Enhanced cellular internalization of near-infrared fluorescent single-walled carbon nanotubes facilitated by a transfection reagent

Functionalized single-walled carbon nanotubes (SWCNTs) hold immense potential for diverse biomedical applications due to their biocompatibility and optical properties, including near-infrared fluorescence. Specifically, SWCNTs have been utilized to target cells as a vehicle for drug delivery and gene therapy, and as sensors for various intracellular biomarkers. While the main internalization route of SWCNTs into cells is endocytosis, methods for enhancing the cellular uptake of SWCNTs are of great importance. In this research, we demonstrate the use of a transfecting reagent for promoting cell internalization of functionalized SWCNTs. We explore different types of SWCNT functionalization, namely single-stranded DNA (ssDNA) or polyethylene glycol (PEG)-lipids, and two different cell types, embryonic kidney cells and adenocarcinoma cells. We show that internalizing PEGylated functionalized SWCNTs is enhanced in the presence of the transfecting reagent, where the effect is more pronounced for negatively charged PEG-lipid. However, ssDNA-SWCNTs tend to form aggregates in the presence of the transfecting reagent, rendering it unsuitable for promoting internalization. For all cases, cellular uptake is visualized by near-infrared fluorescence microscopy, showing that the SWCNTs are typically localized within the lysosome. Generally, cellular internalization was higher in the adenocarcinoma cells, thereby paving new avenues for drug delivery and sensing in malignant cells.

Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

Enzymes serve as pivotal biological catalysts that accelerate essential chemical reactions, thereby influencing a variety of physiological processes. Consequently, the monitoring of enzyme activity and inhibition not only yields crucial insights into health and disease conditions but also forms the basis of research in drug discovery, toxicology, and the understanding of disease mechanisms. In this context, near-infrared (NIR) fluorescent single-walled carbon nanotubes (SWCNTs) have emerged as effective tools for tracking enzyme activity and inhibition through diverse strategies. This perspective explores the physicochemical attributes of SWCNTs that render them well-suited for such monitoring. Additionally, we delve into the various strategies developed so far for successfully monitoring enzyme activity and inhibition, emphasizing the distinctive features of each principle. Furthermore, we contrast the benefits of SWCNT-based NIR probes with conventional gold standards in monitoring enzyme activity. Lastly, we highlight the current challenges faced in this field and suggest potential solutions to propel it forward. This perspective aims to contribute to the ongoing progress in biodiagnostics and seeks to engage the wider community in developing and applying enzymatic assays using SWCNTs.

Carbon Nanomaterial Fluorescent Probes and Their Biological Applications

Fluorescent carbon nanomaterials have broadly useful chemical and photophysical attributes that are conducive to applications in biology. In this review, we focus on materials whose photophysics allow for the use of these materials in biomedical and environmental applications, with emphasis on imaging, biosensing, and cargo delivery. The review focuses primarily on graphitic carbon nanomaterials including graphene and its derivatives, carbon nanotubes, as well as carbon dots and carbon nanohoops. Recent advances in and future prospects of these fields are discussed at depth, and where appropriate, references to reviews pertaining to older literature are provided.

Progress of NIR-II fluorescence imaging technology applied to disease diagnosis and treatment

Near-infrared two-region (NIR-II, 1000-1700 nm) fluorescence imaging has received widespread attention because of its high in vivo penetration depth, high imaging resolution, fast imaging speed and high efficiency, dynamic imaging, and high clinical translatability. This paper reviews the application of NIR-II imaging technology in disease diagnosis and treatment. The paper highlights the latest research progress of commonly used NIR-II imaging materials and the latest progress of multifunctional diagnostic platforms based on NIR-II imaging technology, and discusses the challenges and directions for the development and utilization of novel NIR-II imaging probes.

Nanosensor Chemical Cytometry: Advances and Opportunities in Cellular Therapy and Precision Medicine

With the definition of therapeutics now encompassing transplanted or engineered cells and their molecular products, there is a growing scientific necessity for analytics to understand this new category of drugs. This Perspective highlights the recent development of new measurement science on label-free single cell analysis, nanosensor chemical cytometry (NCC), and their potential for cellular therapeutics and precision medicine. NCC is based on microfluidics integrated with fluorescent nanosensor arrays utilizing the optical lensing effect of a single cell to real-time extract molecular properties and correlate them with physical attributes of single cells. This new class of cytometry can quantify the heterogeneity of the multivariate physicochemical attributes of the cell populations in a completely label-free and nondestructive way and, thus, suggest the vein-to-vein conditions for the safe therapeutic applications. After the introduction of the NCC technology, we suggest the technological development roadmap for the maturation of the new field: from the sensor/chip design perspective to the system/software development level based on hardware automation and deep learning data analytics. The advancement of this new single cell sensing technology is anticipated to aid rich and multivariate single cell data setting and support safe and reliable cellular therapeutics. This new measurement science can lead to data-driven personalized precision medicine.

Nanoreporter Identifies Lysosomal Storage Disease Lipid Accumulation Intracranially

Dysregulated lipid metabolism contributes to neurodegenerative pathologies and neurological decline in lysosomal storage disorders as well as more common neurodegenerative diseases. Niemann-Pick type A (NPA) is a fatal neurodegenerative lysosomal storage disease characterized by abnormal sphingomyelin accumulation in the endolysosomal lumen. The ability to monitor abnormalities in lipid homeostasis intracranially could improve basic investigations and the development of effective treatment strategies. We investigated the carbon nanotube-based detection of intracranial lipid content. We found that the near-infrared emission of a carbon nanotube-based lipid sensor responds to lipid accumulation in neuronal and in vivo models of NPA. The nanosensor detected lipid accumulation intracranially in an acid sphingomyelinase knockout mouse via noninvasive near-infrared spectroscopy. This work indicates a tool to improve drug development processes in NPA, other lysosomal storage diseases, and neurodegenerative diseases.

Single-Walled Carbon Nanotube Sensor Selection for the Detection of MicroRNA Biomarkers for Acute Myocardial Infarction as a Case Study

MicroRNAs (miRNAs) are single-stranded non-coding short ribonucleic acid sequences that take part in many cellular and biological processes. Recent studies have shown that altered expression of miRNAs is involved in pathological processes, and they can thus be considered biomarkers for the early detection of various diseases. Here, we demonstrate a selection and elimination process of fluorescent single-walled carbon nanotube (SWCNT) sensors for miRNA biomarkers based on RNA-DNA hybridization with a complementary DNA recognition unit bound to the SWCNT surface. We use known miRNA biomarkers for acute myocardial infarction (AMI), commonly known as a heart attack, as a case study. We have selected five possible miRNA biomarkers which are selective and specific to AMI and tested DNA-SWCNT sensor candidates with the target DNA and RNA sequences in different environments. Out of these five miRNA sensors, three could recognize the complementary DNA or RNA sequence in a buffer, showing fluorescence modulation of the SWCNT in response to the target sequence. Out of the three working sensors in buffer, only one could function in serum and was selected for further testing. The chosen sensor, SWCNT-miDNA208a, showed high specificity and selectivity toward the target sequence, with better performance in serum compared to a buffer environment. The SWCNT sensor selection pipeline highlights the importance of testing sensor candidates in the appropriate environment and can be extended to other libraries of biomarkers.

Emerging nanotechnology for Alzheimer's disease: From detection to treatment

Alzheimer's disease (AD), one of the most common chronic neurodegenerative diseases, is characterized by memory impairment, synaptic dysfunction, and character mutations. The pathological features of AD are Aβ accumulation, tau protein enrichment, oxidative stress, and immune inflammation. Since the pathogenesis of AD is complicated and ambiguous, it is still challenging to achieve early detection and timely treatment of AD. Due to the unique physical, electrical, magnetic, and optical properties of nanoparticles (NPs), nanotechnology has shown great potential for detecting and treating AD. This review provides an overview of the latest developments in AD detection via nanotechnology based on NPs with electrochemical sensing, optical sensing, and imaging techniques. Meanwhile, we highlight the important advances in nanotechnology-based AD treatment through targeting disease biomarkers, stem-cell therapy and immunotherapy. Furthermore, we summarize the current challenges and present a promising prospect for nanotechnology-based AD diagnosis and intervention.

An update on pathogenesis and clinical scenario for Parkinson's disease: diagnosis and treatment

In severe cases, Parkinson's disease causes uncontrolled movements known as motor symptoms such as dystonia, rigidity, bradykinesia, and tremors. Parkinson's disease also causes non-motor symptoms such as insomnia, constipation, depression and hysteria. Disruption of dopaminergic and non-dopaminergic neural networks in the substantia nigra pars compacta is a major cause of motor symptoms in Parkinson's disease. Furthermore, due to the difficulty of clinical diagnosis of Parkinson's disease, it is often misdiagnosed, highlighting the need for better methods of detection. Treatment of Parkinson's disease is also complicated due to the difficulties of medications passing across the blood-brain barrier. Moreover, the conventional methods fail to solve the aforementioned issues. As a result, new methods are needed to detect and treat Parkinson's disease. Improved diagnosis and treatment of Parkinson's disease can help avoid some of its devastating symptoms. This review explores how nanotechnology platforms, such as nanobiosensors and nanomedicine, have improved Parkinson's disease detection and treatment. Nanobiosensors integrate science and engineering principles to detect Parkinson's disease. The main advantages are their low cost, portability, and quick and precise analysis. Moreover, nanotechnology can transport medications in the form of nanoparticles across the blood-brain barrier. However, because nanobiosensors are a novel technology, their use in biological systems is limited. Nanobiosensors have the potential to disrupt cell metabolism and homeostasis, changing cellular molecular profiles and making it difficult to distinguish sensor-induced artifacts from fundamental biological phenomena. In the treatment of Parkinson's disease, nanoparticles, on the other hand, produce neurotoxicity, which is a challenge in the treatment of Parkinson's disease. Techniques must be developed to distinguish sensor-induced artifacts from fundamental biological phenomena and to reduce the neurotoxicity caused by nanoparticles.

Advanced theragnostics for the central nervous system (CNS) and neurological disorders using functional inorganic nanomaterials

Various types of inorganic nanomaterials are capable of diagnostic biomarker detection and the therapeutic delivery of a disease or inflammatory modulating agent. Those multi-functional nanomaterials have been utilized to treat neurodegenerative diseases and central nervous system (CNS) injuries in an effective and personalized manner. Even though many nanomaterials can deliver a payload and detect a biomarker of interest, only a few studies have yet to fully utilize this combined strategy to its full potential. Combining a nanomaterial's ability to facilitate targeted delivery, promote cellular proliferation and differentiation, and carry a large amount of material with various sensing approaches makes it possible to diagnose a patient selectively and sensitively while offering preventative measures or early disease-modifying strategies. By tuning the properties of an inorganic nanomaterial, the dimensionality, hydrophilicity, size, charge, shape, surface chemistry, and many other chemical and physical parameters, different types of cells in the central nervous system can be monitored, modulated, or further studies to elucidate underlying disease mechanisms. Scientists and clinicians have better understood the underlying processes of pathologies for many neurologically related diseases and injuries by implementing multi-dimensional 0D, 1D, and 2D theragnostic nanomaterials. The incorporation of nanomaterials has allowed scientists to better understand how to detect and treat these conditions at an early stage. To this end, having the multi-modal ability to both sense and treat ailments of the central nervous system can lead to favorable outcomes for patients suffering from such injuries and diseases.

Single-Site Fe-N-C Atom Based Carbon Nanotubes for Mutually Promoted and Synergistic Oncotherapy

A carbon nanotube (CNT) supported single-site Fe-N-C catalyst (CNTs/Fe-N-C) exhibited attractive properties in peroxidase (POD)-like activity and photothermal effect. Herein, we designed a therapeutic platform by wrapping doxorubicin (DOX) in mesoporous CNTs/Fe-N-C with the cell membrane (CM) of breast cancer. The ultimate nanoagent (CNTs/Fe-N-C/DOX/CM) exhibited high antitumor activity on account of its efficient catalytic ability, increased drug release rates, and significant photothermal effect. Due to the POD-like activity, CNTs/Fe-N-C could effectively catalyze hydrogen peroxide (H₂O₂) into cytotoxic hydroxyl radicals (^•OH) for chemodynamic therapy (CDT) of the tumor. Besides, the released DOX not only merely induced the diagnosis of the tumor cells for chemotherapy (CT) but also generated H₂O₂ to promote CDT. Moreover, the photothermal effect of the nanoagent could use for photothermal therapy (PTT). The increasing temperature was conducive to the release of DOX from micropore into the cell, which indirectly enhanced CT and CDT effects. As an intelligent and multifunctional drug delivery platform, the present CNTs/Fe-N-C/DOX/CM nanoagent could be engineered with synergistic treatments and favorable biosafety, which provides a promising paradigm in site-specific antitumor treatment and biomedicine.

Monitoring the Activity and Inhibition of Cholinesterase Enzymes using Single-Walled Carbon Nanotube Fluorescent Sensors

Cholinesterase enzymes are involved in a wide range of bodily functions, and their disruption is linked to pathologies such as neurodegenerative diseases and cancer. While cholinesterase inhibitors are used as drug treatments for diseases such as Alzheimer and dementia at therapeutic doses, acute exposure to high doses, found in pesticides and nerve agents, can be lethal. Therefore, measuring cholinesterase activity is important for numerous applications ranging from the search for novel treatments for neurodegenerative disorders to the on-site detection of potential health hazards. Here, we present the development of a near-infrared (near-IR) fluorescent single-walled carbon nanotube (SWCNT) optical sensor for cholinesterase activity and demonstrate the detection of both acetylcholinesterase and butyrylcholinesterase, as well as their inhibition. We show sub U L^-1 sensitivity, demonstrate the optical response at the level of individual nanosensors, and showcase an optical signal output in the 900-1400 nm range, which overlaps with the biological transparency window. To the best of our knowledge, this is the longest wavelength cholinesterase activity sensor reported to date. Our near-IR fluorescence-based approach opens new avenues for spatiotemporal-resolved detection of cholinesterase activity, with numerous applications such as advancing the research of the cholinergic system, detecting on-site potential health hazards, and measuring biomarkers in real-time.