Photomodulating Carbon Dots for Spatiotemporal Suppression of Alzheimer's β-Amyloid Aggregation

Light-responsive functional nanomaterials as pioneering therapeutics: a paradigm shift to combat age-related disorders

Aging, marked by dysregulated cellular systems, gives rise to a spectrum of age-related disorders, including neurodegeneration, atherosclerosis, immunosenescence, and musculoskeletal issues. These conditions contribute significantly to the global disease burden, posing challenges to health span and economic resources. Current therapeutic approaches, although diverse in mechanism, often fall short in targeting the underlying cellular pathologies. They fail to address the issues compounded by altered pharmacokinetics in the elderly. Nanotechnology emerges as a transformative solution, offering tissue-specific targeted therapies through nanoparticles. Functional nanomaterials (FNMs) respond to internal or external stimuli, with light-responsive nanomaterials gaining prominence. Harnessing the benefits of deep tissue penetration and ease of manipulation particularly in the near-infrared spectrum, light-responsive FNMs present innovative strategies for age-related comorbidities. This review comprehensively summarizes the potential of light-responsive FNM-based approaches for targeting cellular environments in age-related disorders, and also emphasizes the advantages over traditional treatment modalities. Specifically, it focuses on the development of various classes of light-responsive functional nanomaterials including plasmonic nanomaterials, nanomaterials as carriers, upconversion nanomaterials, 2D nanomaterials, transition metal oxide and dichalcogenide nanomaterials and carbon-based nanomaterials against age related diseases. We foresee that such advanced developments in the field of nanotechnology could provide a new hope for clinical diagnosis and treatment of age-related disorders.

Multiexcitation Peaks and Multicolor Emission Nanoassemblies for Transmembrane Cell Imaging and Photoresponsivity Antibacterial

Nanomaterials with photoresponsivity have garnered attention due to their fluorescence imaging, photodynamic, and photothermal therapeutic properties. In this study, a photoresponsivity nanoassembly was developed by using photosensitizers and carbon dots (CDs). Due to their multiple excitation peaks and multicolor fluorescence emission, especially their membrane-permeating properties, these nanoassemblies can label cells with multiple colors and track cell imaging in real time. Additionally, the incorporation of photosensitizers and CDs provides the nanoassemblies with the potential for photodynamic therapy (PDT) and photothermal therapy (PTT). The nanoassemblies effectively suppressed the activity of Escherichia coli and Staphylococcus aureus through PDT and PTT. Moreover, the nanoassemblies exhibited a high affinity for E. coli and S. aureus. These distinct features confer broad-spectrum antibacterial properties to the nanoassemblies. As a photoresponsivity nanoplatform, these nanoassemblies have demonstrated potential applications in the fields of bioimaging and antimicrobial.

Lateral Piezoelectricity of Alzheimer's Aβ Aggregates

Alzheimer's disease (AD) is the most frequent neurodegenerative disorder in the elderly aged over 65. The extracellular accumulation of beta-amyloid (Aβ) aggregates in the brain is considered as the major event worsening the AD symptoms, but its underlying reason has remained unclear. Here the piezoelectric characteristics of Aβ aggregates are revealed. The vector piezoresponse force microscopy (PFM) analysis results exhibit that Aβ fibrils have spiraling piezoelectric domains along the length and a lateral piezoelectric constant of 44.1 pC N-1. Also, the continuous sideband Kelvin probe force microscopy (KPFM) images display that the increment of charge-induced surface potential on a single Aβ fibril is allowed to reach above +1700 mV in response to applied forces. These findings shed light on the peculiar mechano-electrical surface properties of pathological Aβ fibrils that exceed those of normal body components.

Orange carbon dots based smart sensing platforms for rapid, visual, quantitative identification of sodium copper chlorophyllin

A highly affordable, sensitive and portable detection platform for the quantitative identification of sodium copper chlorophyllin (SCC) in food and environment is a crucial need. Even though many carbon dots (CDs) based sensors have been developed, few reports on using CDs as optical probes for SCC detection have been published so far. In this paper, orange luminescent CDs (OLCDs) were prepared via solvothermal method, which have high fluorescence quantum yield (27.20 %) and excellent photostability. OLCDs can detect SCC via inner filter effect (IFE), with fast response, high selectivity, outstanding sensitivity and superior anti-interference ability. Benefiting from the remarkable properties of OLCDs, a portable sensing platform was triumphantly constructed, which facilitated the in situ, real-time quantitative determination of SCC in diverse actual samples, by catching the fluorescence change of OLCDs-based paper sensors via smartphone RGB colorimetric analysis. This first CDs-based smart sensing system displays great potential for quantification of SCC in various fields.

Diagnosis and therapy of Alzheimer's disease: Light-driven heterogeneous redox processes

Light-driven heterogeneous processes are promising approaches for diagnosing and treating Alzheimer's disease (AD) by regulating its relevant biomolecules. The molecular understanding of the heterogeneous interface environment and its interaction with target biomolecules is important. This review critically appraises the advances in AD early diagnosis and therapy employing heterogeneous light-driven redox processes, encompassing photoelectrochemical (PEC) biosensing, photodynamic therapy, photothermal therapy, PEC therapy, and photoacoustic therapy. The design strategies for heterogeneous interfaces based on target biomolecules and applications are also compiled. Finally, the remaining challenges and future perspectives are discussed. The present review may promote the fundamental understanding of AD diagnosis and therapy and facilitate interdisciplinary studies at the junction of nanotechnology and bioscience.

A Theoretical Investigation into the Oligomer Structure of Carbon Dots Formed from Small-Molecule Precursors

In-depth insights into the oligomers of carbon dots (CDs) prepared from small-molecule precursors are important in the study of the carbonization mechanism of CDs and for our knowledge of their complex structure. Herein, citric acid (CA) and ethylenediamine (EDA) were used as small-molecule precursors to prepare CDs in an aqueous solution. The structure of oligomers acquired from CA and EDA in different molar ratios and their formation process were first studied using density functional theory, including the dispersion correction (DFT-D3) method. The results showed that the energy barrier of dimer cyclization was higher than that of its linear polymerization, but the free energy of the cyclized product was much lower than that of its reactant, and IPCA (5-oxo-1,-2,3,5-tetrahydroimidazo [1,2-a]pyridine-7-carboxylic acid) could therefore be obtained under certain conditions. The oligomers obtained from different molar ratios of EDA and CA were molecular clusters formed by short polyamide chains through intermolecular forces; with the exception of when the molar ratio of EDA to CA was 0.5, excessive CA did not undergo an amidation reaction but rather attained molecular clusters directly through intermolecular forces. These oligomers exhibited significant differences in their surface functional groups, which would affect the carbonization process and the surface structure of CDs.

The dissolution, reassembly and further clearance of amyloid-β fibrils by tailor-designed dissociable nanosystem for Alzheimer's disease therapy

The fibrillation of amyloid-β (Aβ) is the critical causal factor in Alzheimer's disease (AD), the dissolution and clearance of which are promising for AD therapy. Although many Aβ inhibitors are developed, their low Aβ-binding affinity results in unsatisfactory effect. To solve this challenge, the Aβ sequence-matching strategy is proposed to tail-design dissociable nanosystem (B6-PNi NPs). Herein, B6-PNi NPs aim to improve Aβ-binding affinity for effective dissolution of amyloid fibrils, as well as to interfere with the in vivo fate of amyloid for Aβ clearance. Results show that B6-PNi NPs decompose into small nanostructures and expose Aβ-binding sites in response to AD microenvironment, and then capture Aβ via multiple interactions, including covalent linkage formed by nucleophilic substitution reaction. Such high Aβ-binding affinity disassembles Aβ fibrils into Aβ monomers, and induces the reassembly of Aβ&nanostructure composite, thereby promoting microglial Aβ phogocytosis/clearance via Aβ receptor-mediated endocytosis. After B6-PNi NPs treatment, the Aβ burden, neuroinflammation and cognitive impairments are relieved in AD transgenic mice. This work provides the Aβ sequence-matching strategy for Aβ inhibitor design in AD treatment, showing meaningful insight in biomedicine.

Neurophotonics: a comprehensive review, current challenges and future trends

The human brain, with its vast network of billions of neurons and trillions of synapses (connections) between diverse cell types, remains one of the greatest mysteries in science and medicine. Despite extensive research, an understanding of the underlying mechanisms that drive normal behaviors and response to disease states is still limited. Advancement in the Neuroscience field and development of therapeutics for related pathologies requires innovative technologies that can provide a dynamic and systematic understanding of the interactions between neurons and neural circuits. In this work, we provide an up-to-date overview of the evolution of neurophotonic approaches in the last 10 years through a multi-source, literature analysis. From an initial corpus of 243 papers retrieved from Scopus, PubMed and WoS databases, we have followed the PRISMA approach to select 56 papers in the area. Following a full-text evaluation of these 56 scientific articles, six main areas of applied research were identified and discussed: (1) Advanced optogenetics, (2) Multimodal neural interfaces, (3) Innovative therapeutics, (4) Imaging devices and probes, (5) Remote operations, and (6) Microfluidic platforms. For each area, the main technologies selected are discussed according to the photonic principles applied, the neuroscience application evaluated and the more indicative results of efficiency and scientific potential. This detailed analysis is followed by an outlook of the main challenges tackled over the last 10 years in the Neurophotonics field, as well as the main technological advances regarding specificity, light delivery, multimodality, imaging, materials and system designs. We conclude with a discussion of considerable challenges for future innovation and translation in Neurophotonics, from light delivery within the brain to physical constraints and data management strategies.

Unraveling brain diseases: The promise of brain-on-a-chip models

Brain disorders, encompassing a wide spectrum of neurological and psychiatric conditions, present a formidable challenge in modern medicine. Despite decades of research, the intricate complexity of the human brain still eludes comprehensive understanding, impeding the development of effective treatments. Recent advancements in microfluidics and tissue engineering have led to the development of innovative platforms known as "Brain-on-a-Chip" (BoC) i.e., advanced in vitro systems that aim to replicate the microenvironment of the brain with the highest possible fidelity. This technology offers a promising test-bed for studying brain disorders at the cellular and network levels, providing insights into disease mechanisms, drug screening, and, in perspective, the development of personalized therapeutic strategies. In this review, we provide an overview of the BoC models developed over the years to model and understand the onset and progression of some of the most severe neurological disorders in terms of incidence and debilitation (stroke, Parkinson's, Alzheimer's, and epilepsy). We also report some of the cutting-edge therapeutic approaches whose effects were evaluated by means of these technologies. Finally, we discuss potential challenges, and future perspectives of the BoC models.

Novel photocatalytic carbon dots: efficiently inhibiting amyloid aggregation and quickly disaggregating amyloid aggregates

Amyloid aggregation is implicated in the pathogenesis of various neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). It is critical to develop high-performance drugs to combat amyloid-related diseases. Most identified nanomaterials exhibit limited biocompatibility and therapeutic efficacy. In this work, we used a solvent-free carbonization process to prepare new photo-responsive carbon nanodots (CNDs). The surface of the CNDs is densely packed with chemical groups. CNDs with large, conjugated domains can interact with proteins through π-π stacking and hydrophobic interactions. Furthermore, CNDs possess the ability to generate singlet oxygen species (1O2) and can be used to oxidize amyloid. The hydrophobic interaction and photo-oxidation can both influence amyloid aggregation and disaggregation. Thioflavin T (ThT) fluorescence analysis and circular dichroism (CD) spectroscopy indicate that CNDs can block the transition of amyloid from an α-helix structure to a β-sheet structure. CNDs demonstrate efficacy in alleviating cytotoxicity induced by Aβ42 and exhibit promising blood-brain barrier (BBB) permeability. CNDs have small size, low biotoxicity, good fluorescence and photocatalytic properties, and provide new ideas for the diagnosis and treatment of amyloid-related diseases.

"Five birds one stone" tri-modal monitoring driven lab-on-magnetic aptasensor for accurate pathogen detection and enhanced germicidal application

The effective combination of ultra-precise detection and on-demand sterilization stands out as one of the most valuable antifouling methods to combat pathogenic bacteria source and ensure the environment and food safety. Herein, an innovative "five birds one stone" aptasensor has been reported. It integrates magnetic separation, tri-modal precision detection, and efficient sterilization for monitoring of Staphylococcus aureus. Firstly, as a switch of the aptasensor, aptamer-modified potassium chloride-doped carbon dots (apt/KCl@CDs) could be adsorbed onto the surface of magnetic multi-walled carbon nanotube composites (M-MWCNTs) through π-π stacking, which could be replaced by the specific binding of the target bacteria to the aptamer. The mutual interference between the nanomaterials could be eliminated by this reverse magnetosorption strategy, enhancing the test sensitivity. In addition to the fluorescence properties, the peroxidase activity possessed by apt/KCl@CDs enables the conversion of the (3,3',5,5'-tetramethylbenzidine) TMB-H2O2 colorimetric system to a photothermal modal. Then, the ultra-precision detection in the assay was achieved by the fluorescence-colorimetric-photothermal tri-modal sensing from the formation of S. aureus-apt/KCl@CDs in the supernatant. Besides, the efficient sterilization could be ensured by adsorbing the apt/KCl@CDs on the surface of S. aureus, generating toxic •OH for direct attacking cells. This was the first report that was more beneficial for bacterial eradication. The detection limits of fluorescence, colorimetric and photothermal modals were 4.81 cfu/mL, 3.40 cfu/mL and 6.74 cfu/mL, respectively. The magnetic nanoplatform integrating tri-modal detection-sterilization meets the demand for highly sensitive and precise detection in different scenarios, providing immediate control for pathogens and broad application prospects.

Chiral nanomaterial-based approaches for diagnosis and treatment of protein-aggregated neurodiseases: current status and future opportunities

Protein misfolding and its aggregation, known as amyloid aggregates (Aβ), are some of the major causes of more than 20 diseases such as Parkinson's disease, Alzheimer's disease, and type 2 diabetes. The process of Aβ formation involves an energy-driven oligomerization of Aβ monomers, leading to polymerization and eventual aggregation into fibrils. Aβ fibrils exhibit multilevel chirality arising from its amino acid residues and the arrangement of folded polypeptide chains; thus, a chirality-driven approach can be utilized for the detection and inhibition of Aβ fibrils. In this regard, chiral nanomaterials have recently opened new possibilities for various biomedical applications owing to their stereoselective interaction with biological systems. Leveraging this chirality-driven approach with chiral nanomaterials against protein-aggregated diseases could yield promising results, particularly in the early detection of Aβ forms and the inhibition of Aβ aggregate formation via specific and strong "chiral-chiral interaction." Despite the advantages, the development of advanced theranostic systems using chiral nanomaterials against protein-aggregated diseases has received limited attention so far because of considerably limited formulations for chiral nanomaterials and lack of information of their chiroptical behavior. This review aims to present the current status of chiral nanomaterials explored for detecting and inhibiting Aβ forms. This review covers the origin of chirality in amyloid fibrils and nanomaterials and different chiral detection methods; furthermore, different chiral nanosystems such as chiral plasmonic nanomaterials, chiral carbon-based nanomaterials, and chiral nanosurfaces, which have been used so far for different therapeutic applications against protein-aggregated diseases, are discussed in detail. The findings from this review may pave the way for the development of novel approaches using chiral nanomaterials to combat diseases resulting from protein misfolding and can further be extended to other disease forms.

Surface Modification Functionalized Carbon Dots

Carbon dots (CDs) smaller than 10 nm constitute a new type of fluorescent carbon-based nanomaterial. They have attracted much attention owing to their unique structures and excellent photoelectric properties. Primitive CDs usually comprise carbon and oxygen and are synthesized in one step from various natural products or synthetic organic compounds, usually via microwave or hydrothermal methods. However, the uniformity of surface functional groups often make CDs lack the diversity of active sites required for specific applications. Therefore, the functionalization of CDs by specific groups is a powerful strategy for improving their photophysical and photochemical properties. This paper reviews surface modification strategies to overcome these shortcomings. Functionalizing CDs using covalent or non-covalent modification can give them unique properties and broaden their applicability.

Macrophage membrane-encapsulated nitrogen-doped carbon quantum dot nanosystem for targeted treatment of Alzheimer's disease: Regulating metal ion homeostasis and photothermal removal of β-amyloid

The abnormal aggregation of β-amyloid protein (Aβ) is a major contributor to Alzheimer's disease (AD). Cu2+ homeostasis imbalance can lead to the aggregation of Aβ, resulting in cytotoxic oligomers and fibrous aggregates, causing neuroinflammation and nerve cell damage, ultimately leading to AD. In this study, we synthesized nitrogen-doped carbon quantum dot (CQD), and designed a macrophage membrane (RAW-M) encapsulated CQD nanosystem for the first time. The abundant nitrogen-containing groups on the surface of CQD effectively capture excess Cu2+ and inhibit rapid Aβ aggregation. Additionally, the good photothermal properties of CQD dissolve the formed fiber precipitates under near-infrared light (NIR). In vitro and in vivo studies showed that the nanosystem significantly improved BBB permeability under laser irradiation, enhancing its ability to cross the BBB and overcome traditional anti-AD drug limitations. In vivo investigations conducted on APP/PS1 mice indicate that the nanosystem strongly reduced Aβ deposition, mitigated neuroinflammation, and ameliorates deficits in learning and memory. Overall, our nanocarrier approach adjusts metal ion homeostasis, inhibits abnormal Aβ aggregation, and uses excellent photothermal properties to depolymerize mature Aβ fibrils to protect cells from Aβ neurotoxicity, providing an effective strategy for Aβ-targeted treatment of AD.

Carbon dots derived from citric acid and urea as fluorometric probe for determining melamine contamination in infant formula sample

Melamine has been intentionally added into food products to increase the protein count at less cost, especially in dairy products for infant resulting in serious adverse effects on health of consumers. Therefore, this study aimed to develop a method to quantify melamine in dairy products based on the change of fluorescent properties of carbon dots (CDs) as sensing probe. CDs with green-fluorescent emission were synthesized from citric acid and urea under microwave irradiation. The synthesized CDs emitted fluorescence at the maximum wavelength of 538 nm with excitation wavelength of 410 nm. Thus, they provided high sensitivity and selectivity on melamine detection by which fluorescent emission of the CDs was increasingly quenched upon increasing melamine concentrations. Optimal conditions for melamine determination using the CDs was under pH 6, volume ratio between CDs and sample of 2:8 and reaction time of 15 min. The developed method provided high precision of melamine determination with less than 5% of %RSD (n = 5), wide detection range from 1.0 to 200.0 ppm, and high sensitivity with limit of detection (LOD) of 0.47 ppm and limit of quantification (LOQ) of 1.56 ppm, which is within the regulated level by the Food and Drug Administration of the United States for melamine in dairy products. Several analytical characterization techniques were conducted to elucidate the reaction mechanism between CDs and melamine, and the hydrogen bonding interaction was proposed.

Current emerging novel therapies for Alzheimer's disease and the future prospects of magneto-mechanical force therapy

Alzheimer's disease (AD) is the most common neurodegenerative disease among the elderly, and the morbidity increases with the aging population aggravation. The clinical symptoms of AD mainly include cognitive impairment and memory loss, which undoubtedly bring a huge burden to families and society. Currently, the drugs in clinical use only improve the symptoms of AD but do not cure or prevent the progression of the disease. Therefore, it is urgent for us to develop novel therapeutic strategies for effective AD treatment. To provide a better theoretical basis for exploring novel therapeutic strategies in future AD treatment, this review introduces the recent AD treatment technologies from three aspects, including nanoparticle (NP) based drug therapy, biological therapy and physical therapy. The nanoparticle-mediated therapeutic approaches at the nanomaterial-neural interface and biological system are described in detail, and in particular the magneto-regulated strategies by magnetic field actuating magnetic nanoparticles are highlighted. Promising application of magneto-mechanical force regulated strategy in future AD treatment is also addressed, which offer possibilities for the remote manipulation in a precise manner. In the future, it may be possible for physicians to realize a remote, precise and effective therapy for AD using magneto-mechanical force regulated technology based on the combination of magnetic nanoparticles and an external magnetic field.

Design of aggregation-induced emission-active fluorogen-based nanoparticles for imaging and scavenging Alzheimer's β-amyloid by photo-oxygenation

Photo-oxygenation has emerged as an effective modality for scavenging Alzheimer's amyloid-β (Aβ) plaques. However, limitations of the current photo-oxidants, such as low Aβ-targeting and single functionality, hinder the scavenging of Aβ plaques via photo-oxygenation. Herein, based on an aggregation-induced emission (AIE)-active fluorogen (named TPMD), we designed AIE photo-oxidant nanoparticles (T-LD NPs) for Aβ imaging, inhibition, and disaggregation. The T-LD NPs were prepared by the assembly of hydrophobic TPMD with an Aβ-targeting peptide (LPPFD, L) conjugated amphiphilic polymer (DSPE-PEG). Such T-LD NPs could specifically label Aβ plaques for image-guided therapy. Under laser irradiation, T-LD NPs generated a plethora of reactive oxygen species (ROS), including 1O2, ˙OH, and O2˙-, to oxygenate Aβ species, leading to the potent inhibition of Aβ fibrillization, and significant alleviation of Aβ-mediated neurotoxicity (36% to 10% at 20 μg mL-1). Notably, T-LD NPs could rapidly disaggregate mature Aβ fibrils into fractured β-sheet rich aggregates via photo-oxygenation, resulting in alleviated cytotoxicity. In vivo studies revealed that the photo-activated T-LD NPs scavenged amyloid plaques in the transgenic C. elegans strain CL2006 and extended the lifespan by 4 days. Taken together, this multifunctional T-LD NP integrated Aβ-targeting, near-infrared fluorescence imaging, and photo-oxygenation, provides a new strategy for the development of multifunctional AIE photo-oxidants for the treatment of Alzheimer's disease.

Methylene Blue-Doped Carbonized Polymer Dots: A Potent Photooxygenation Scavenger Targeting Alzheimer's β-Amyloid

The abnormal aggregation of β-amyloid protein (Aβ) is one of the main pathological hallmarks of Alzheimer's disease (AD), and thus development of potent scavengers targeting Aβ is considered an effective strategy for AD treatment. Herein, photosensitizer-doped carbonized polymer dots (PS-CPDs) were synthesized by a one-step hydrothermal method using photosensitizer (PS) and o-phenylenediamine (oPD) as precursors, and furtherly applied to inhibit Aβ aggregation via photooxygenation. The inhibition efficiency of such PS-CPDs can be adjusted by varying the type of photosensitizer, and among them, methylene blue-doped carbonized polymer dots (MB-CPDs) showed the strongest photooxygenation inhibition capability. The results demonstrated that under 650 nm NIR light irradiation, MB-CPDs (2 μg/mL) produced reactive oxygen species (ROS) to efficiently inhibit Aβ fibrillization and disaggregate mature Aβ fibrils and increased the cultured cell viability from 50% to 83%. In vivo studies confirmed that MB-CPDs extended the lifespan of AD nematodes by 4 days. Notably, the inhibitory capability of MB-CPDs is much stronger than that of MB and previously reported carbonized polymer dots. This work indicated that potent photooxygenation carbon dots can be obtained by using a photosensitizer as one of the precursors, and the results have provided new insights into the design of potent photooxygenation carbon nanomaterials targeting Aβ in AD treatment.

C3N nanodots inhibits Aβ peptides aggregation pathogenic path in Alzheimer's disease

Despite the accumulating evidence linking the development of Alzheimer's disease (AD) to the aggregation of Aβ peptides and the emergence of Aβ oligomers, the FDA has approved very few anti-aggregation-based therapies over the past several decades. Here, we report the discovery of an Aβ peptide aggregation inhibitor: an ultra-small nanodot called C3N. C3N nanodots alleviate aggregation-induced neuron cytotoxicity, rescue neuronal death, and prevent neurite damage in vitro. Importantly, they reduce the global cerebral Aβ peptides levels, particularly in fibrillar amyloid plaques, and restore synaptic loss in AD mice. Consequently, these C3N nanodots significantly ameliorate behavioral deficits of APP/PS1 double transgenic male AD mice. Moreover, analysis of critical tissues (e.g., heart, liver, spleen, lung, and kidney) display no obvious pathological damage, suggesting C3N nanodots are biologically safe. Finally, molecular dynamics simulations also reveal the inhibitory mechanisms of C3N nanodots in Aβ peptides aggregation and its potential application against AD.

Advancements in the Application of Nanomedicine in Alzheimer's Disease: A Therapeutic Perspective

Alzheimer's disease (AD) is a progressive neurodegenerative disease that affects most people worldwide. AD is a complex central nervous system disorder. Several drugs have been designed to cure AD, but with low success rates. Because the blood-brain and blood-cerebrospinal fluid barriers are two barriers that protect the central nervous system, their presence has severely restricted the efficacy of many treatments that have been studied for AD diagnosis and/or therapy. The use of nanoparticles for the diagnosis and treatment of AD is the focus of an established and rapidly developing field of nanomedicine. Recent developments in nanomedicine have made it possible to effectively transport drugs to the brain. However, numerous obstacles remain to the successful use of nanomedicines in clinical settings for AD treatment. Furthermore, given the rapid advancement in nanomedicine therapeutics, better outcomes for patients with AD can be anticipated. This article provides an overview of recent developments in nanomedicine using different types of nanoparticles for the management and treatment of AD.

An ultrasensitive colorimetric biosensor for the detection of Gram-positive bacteria by integrating paper-based enrichment and carbon dot-based selective recognition

Rapid screening of bacteria by low-cost and eco-friendly material-based approaches is still a major challenge. Herein, a colorimetric biosensor was designed for the ultrasensitive and rapid detection of Gram-positive bacteria. The biosensor exploited polydopamine and polyethyleneimine (PDA-PEI)-modified papers for separating bacteria and carbon dots (CDs) for selective colorimetric detection of Gram-positive bacteria. Noble metal-free CDs can target Gram-positive bacteria by binding with peptidoglycan and possess peroxidase-like activity. Thus, they can avert the step of modifying recognition probes, facilitating biosensor fabrication, and reducing the cost. This biosensor can detect S. aureus as low as 1 cfu mL^-1, L. monocytogenes as low as 5 cfu mL^-1, and B. subtilis as low as 9 cfu mL^-1 within 55 min. In addition, a portable device was constructed to enable convenient and on-site quantitative detection of Gram-positive bacteria. The feasibility of the biosensor was verified by detecting Gram-positive bacteria in eggshell and sausage samples with recoveries ranging from 91.2% to 110%.

Congo Red-Derived Carbon Dots: Simultaneously as Fluorescence Probe for Protein Aggregates, Inhibitor for Protein Aggregation, and Scavenger of Free Radicals

The pathological aggregation of some proteins is claimed to be highly related to several human diseases, such as β-amyloid 1-42 (Aβ₄₂ ) to Alzheimer's disease (AD), islet amyloid polypeptide, and insulin to type 2 diabetes mellitus. Therefore, it is in desperate need to develop effective methods for detection of protein aggregates and inhibition of abnormal aggregation. Herein, to construct all-in-one probe with both diagnosis and treatment potentials for protein aggregation diseases, Congo red (CR), a classical staining reagent with red fluorescence signal output for protein aggregates, is deliberately adopted to react with three different reductive carbon sources and ammonium persulfate to generate three CR-derived carbon dots (CDs). The obtained CDs exhibit the capabilities of turn-on red fluorescence imaging of protein aggregates, and/or inhibition of protein aggregation as well as scavenging of free radicals. Among them, CA-CDs, using citric acid as the reductive carbon source, demonstrate the superiority to the other two studied CDs in integrating all of these functions, and particularly exert excellent cytoprotection effect against toxic Aβ₄₂ species, possessing tremendous potential in diagnosis and treatment of AD for future study. The present study paves a new way to develop all-in-one CDs for the protein disease research.

Construction of a DNA Nanoassembly Based on Spatially Ordered Recognition Elements for Inhibiting β-Amyloid Aggregation

A β-amyloid (Aβ) aggregation process is a spontaneous process where the original random coil or helical structure changes into a regularly arranged β-sheet structure. The development of inhibitors with the features of low cost, high efficiency, and biosafety by targeting Aβ self-aggregation is significant for Alzheimer's disease treatment. However, the issues of low inhibition efficiency under low concentrations of inhibitors and biological toxicity are currently to be addressed. To resolve the above problems, a DNA nanoassembly (HCR-Apt) based on spatially ordered recognition elements was constructed by targeted disruption of Aβ ordered arrangement. It was discovered that HCR-Apt could inhibit effectively the fibrillation of Aβ₄₀ monomers and oligomers at substoichiometric ratios. This may be due to orderly arrangement of aptamers in rigid nanoskeletons for enhancing the recognition interaction between aptamers and Aβ₄₀. The strong interaction between HCR-Apt and Aβ₄₀ limited the flexible conformational conversion of Aβ₄₀ molecules, thereby inhibiting their self-assembly. Computational simulations and experimental analysis revealed the interactions of Apt₄₂ with Aβ₄₀, which explained different inhibition effects on the fibrillation of Aβ₄₀ monomers and oligomers. Furthermore, the analysis of tyrosine intrinsic fluorescence spectra and surface plasmon resonance imaging showed that the interaction of HCR-Apt and Aβ₄₀ was stronger than that of Apt₄₂ and Aβ₄₀. These findings contributed to establishing a promising method of boosting the recognition interaction by orderly arrangement of recognition elements. Taken together, this work is expected to provide a simple and efficient strategy for inhibiting Aβ aggregation, expanding aptamer's application potential in neurodegenerative diseases.

Epigallocatechin gallate-derived carbonized polymer dots: A multifunctional scavenger targeting Alzheimer's β-amyloid plaques

The design of high-efficiency scavengers targeting β-amyloid protein (Aβ) plaques in the progress of Alzheimer's disease (AD) has been recognized as an effective way to prevent and treat AD. Herein, epigallocatechin gallate (EGCG)-derived carbonized polymer dots (E-CPDs) were synthesized for the first time via a hydrothermal method using EGCG, an Aβ inhibitor, as one of the raw materials. The inhibitory efficiency and fluorescent property of E-CPDs were elegantly modulated by adjusting the molar ratio of EGCG to nitrogen-containing dopant, o-phenylenediamine (oPD), and 75E-CPDs fabricated with 75 mM EGCG and 50 mM oPD showed the highest inhibitory capability. The multifunctionality of 75E-CPDs on inhibition of Aβ fibrillization, Aβ fibrils disaggregation, amyloid fluorescent detection, and intracellular reactive oxygen species scavenging was demonstrated. 75E-CPDs inhibited the formation of β-sheet-rich Aβ aggregates, alleviated Aβ-induced cytotoxicity of cultured cells from 47% to 15%, and prolonged the lifespan of AD nematodes by scavenging in vivo amyloid plaques, demonstrating much higher performance than either EGCG or EGCG-free carbon dots. Notably, 75E-CPDs could rapidly disaggregate Aβ fibrils on "second" scale, faster than any other disaggregating agents. The aromatic structure as well as hydroxyl and carboxyl groups existing on 75E-CPDs surface, which would interact with Aβ species via hydrogen bonding, electrostatic interactions, and hydrophobic interactions, played critical roles in their inhibition and disaggregation capabilities. This work reveals that potent CDs can be fabricated by using an Aβ inhibitor as the precursor, providing a new perspective for the design of multifunctional scavengers targeting amyloid plaques. STATEMENT OF SIGNIFICANCE: Alzheimer's disease (AD) is one of the top ten causes of death worldwide and seriously threatens human health. Recently, carbon nanomaterials have attracted much attention because of their good biocompatibility and capability in modulating Aβ aggregation via multiple interactions. This work has for the first time fabricated epigallocatechin gallate-derived carbonized polymer dots (E-CPDs) and revealed the multifunctional potency of E-CPDs on alleviating the multifaced symptoms associated with β-amyloid protein (Aβ) fibrillization in the progression of AD. Notably, E-CPDs exhibited enhanced fluorescence emission upon binding to Aβ fibrils, possessing potential as Aβ fluorescent probes. It is believed that this work would open a new horizon in the design of multifunctional carbon nanomaterials as a potent amyloid scavenger for AD theranostics.

Functional Carbon Quantum Dots for Ocular Imaging and Therapeutic Applications

Carbon quantum dots (CDs) are a class of emerging carbonaceous nanomaterials that have received considerable attention due to their excellent fluorescent properties, extremely small size, ability to penetrate cells and tissues, ease of synthesis, surface modification, low cytotoxicity, and superior water dispersion. In light of these properties, CDs are extensively investigated as candidates for bioimaging probes, efficient drug carriers, and disease diagnostics. Functionalized CDs represent a promising therapeutic candidate for ocular diseases. Here, this work reviews the potential use of functionalized CDs in the diagnosis and treatment of eye-related diseases, including the treatment of macular and anterior segment diseases, as well as targeting Aβ amyloids in the retina.

Linnaeite Mineral for NIR Light-Triggered Disruption of Alzheimer's Pore-Forming Aβ Oligomers

Minerals in the Earth's crust have contributed to the natural functioning of ecosystems via biogeochemical interactions. Linnaeite is a cobalt sulfide mineral with a cubic spinel structure that promotes charge transfer reactions with its surroundings. Here we report the hidden feature of linnaeite mineral to dissociate Alzheimer's β-amyloid (Aβ) oligomers under near-infrared (NIR) light irradiation. Alzheimer's disease (AD) is a neurodegenerative disorder caused by the abnormal accumulation of self-assembled Aβ peptides in the elderly brain. The β-sheet structured pore-forming Aβ oligomer (βPFO) is the most neurotoxic species exacerbating the symptoms of AD. However, a therapeutic agent that is capable of inactivating βPFO has not yet been developed. Our microscopic and spectroscopic analysis results have revealed that NIR-excited linnaeite mineral can modulate the structure of βPFO by inducing oxidative modifications. We have verified that linnaeite mineral is biocompatible with and has a mitigating effect on the neurotoxicity of βPFO. This study suggests that minerals in nature have potential as drugs to reduce AD pathology.

Transcranial deep-tissue phototherapy for Alzheimer's disease using low-dose X-ray-activated long-afterglow scintillators

Non-invasive phototherapy has been emerging as an ambitious tactic for suppression of amyloid-β (Aβ) self-assembly against Alzheimer's disease (AD). However, it remains a daunting challenge to develop efficient photosensitizers for Aβ oxygenation that are activatable in a deep brain tissue through the scalp and skull, while reducing side effects on normal tissues. Here, we report an Aβ targeted, low-dose X-ray-excitable long-afterglow scintillator (ScNPs@RB/Ab) for efficient deep-brain phototherapy. We demonstrate that the as-synthesized ScNPs@RB/Ab is capable of converting X-rays into visible light to activate the photosensitizers of rose bengal (RB) for Aβ oxygenation through the scalp and skull. We show that the ScNPs@RB/Ab persistently emitting visible luminescence can substantially minimize the risk of excessive X-ray exposure dosage. Importantly, peptide KLVFFAED-functionalized ScNPs@RB/Ab shows a blood-brain barrier permeability. In vivo experimental results validated that ScNPs@RB/Ab alleviated Aβ burden and slowed cognitive decline in triple-transgenic AD model mice at extremely low X-ray doses without side effects. Our study paves a new pathway to develop high-efficiency transcranial AD phototherapy. STATEMENT OF SIGNIFICANCE: Non-invasive phototherapy has been emerging as an ambitious tactic for suppression of amyloid-β (Aβ) self-assembly against Alzheimer's disease (AD). However, it remains a daunting challenge to develop efficient photosensitizers for Aβ oxygenation that are activatable in a deep brain tissue through the scalp and skull, while reducing side effects on normal tissues. Herein, we report an Aβ targeted, low-dose X-ray-excitable long-afterglow scintillators (ScNPs@RB/Ab) for efficient deep-brain phototherapy. In vivo experimental results validated that ScNPs@RB/Ab alleviated Aβ burden and slowed cognitive decline in triple-transgenic AD model mice at extremely low X-ray doses without side effects.

Applications of Carbon Dots for the Treatment of Alzheimer's Disease

There are currently approximately 50 million victims of Alzheimer's disease (AD) worldwide. The exact cause of the disease is unknown at this time, but amyloid plaques and neurofibrillary tangles in the brain are hallmarks of the disease. Current drug treatments for AD may slow the progression of the disease and improve the quality of life of patients, but they are often only minimally effective and are not cures. A major obstacle to developing and delivering more effective drug therapies is the presence of the blood-brain barrier (BBB), which prevents many compounds with therapeutic potential from reaching the central nervous system. Nanotechnology may provide a solution to this problem. Among the medical nanomaterials currently being studied, carbon dots (CDs) have attracted widespread attention because of their ability to cross the BBB, non-toxicity, and potential for drug/gene delivery.

Advanced nanomaterials for modulating Alzheimer's related amyloid aggregation

Alzheimer's disease (AD) is a common neurodegenerative disease that brings about enormous economic pressure to families and society. Inhibiting abnormal aggregation of Aβ and accelerating the dissociation of aggregates is treated as an effective method to prevent and treat AD. Recently, nanomaterials have been applied in AD treatment due to their excellent physicochemical properties and drug activity. As a drug delivery platform or inhibitor, various excellent nanomaterials have exhibited potential in inhibiting Aβ fibrillation, disaggregating, and clearing mature amyloid plaques by enhancing the performance of drugs. This review comprehensively summarizes the advantages and disadvantages of nanomaterials in modulating amyloid aggregation and AD treatment. The design of various functional nanomaterials is discussed, and the strategies for improved properties toward AD treatment are analyzed. Finally, the challenges faced by nanomaterials with different dimensions in AD-related amyloid aggregate modulation are expounded, and the prospects of nanomaterials are proposed.

Detection of Cobalamin and In Vitro Cell Imaging Based on Nitrogen-Doped Yellow Fluorescent Carbon Dots with Nano Architectonics

As novel fluorescent nanomaterials, carbon dots have attracted increasing research attention because of their simple synthesis, robust fluorescence, low toxicity, and easy functionalisation. Previous research was focused on preparing carbon dots from biomass and chemical materials; however, most of these carbon dots exhibited blue fluorescence. Moreover, the fluorescence quantum yield was generally low, significantly limiting their application in biological imaging. To broaden the application scope of carbon dots, this study prepared long-wavelength emitting nano-carbon dots that exhibited increased quantum yield. Novel N-doped yellow fluorescent nano-carbon dots (Y-CDs) were synthesised via a hydrothermal method using L-tartaric acid and urea as the precursors. The Y-CDs had a high quantum yield (15.9%) and demonstrated photostability at various pHs, temperatures, and ionic strengths. The Y-CDs could detect cobalamin effectively and selectively, showing a linear relationship between fluorescence intensity and cobalamin concentration. The related coefficient was 0.997, and the detection limit was 2.101 μmol/L. In addition, the Y-CDs were successfully used as an imaging probe for MDA-MB-231 cells. Therefore, the Y-CDs developed in this study can be used for cobalamin detection and cell imaging.

Decorated Polyetheretherketone Implants with Antibacterial and Antioxidative Effects through Layer-by-Layer Nanoarchitectonics Facilitate Diabetic Bone Integration with Infection

Patients suffering diabetic bone defects still need some new and effective strategies to achieve enhanced prognostic effects. Although medical implants are the common treatment of bone defects, the excessive oxidative stress and high risk of bacterial infection in diabetes mellitus lead to a higher risk of implant failure. To improve the healing ability of diabetic bone defects, herein, polyetheretherketone (PEEK) was modified through a developed layer-by-layer (LBL) construction strategy to obtain multifunctional PEEK (SP@(TA-GS/PF)*3) by the assembly of tannic acid (TA), gentamicin sulfate (GS) and Pluronic F127 (PF127) on the basis of prepared porous PEEK through sulfonation (SPEEK). The prepared SP@(TA-GS/PF)*3 exhibited sustained antimicrobial activity and enhanced the differentiation of osteoblast (MC3T3-E1) for needed osteogenesis. Moreover, SP@(TA-GS/PF)*3 scavenged excessive oxidative stress to promote the growth of H₂O₂ damaged HUVEC with enhanced secretion of VEGF for neovascularization. In addition, the remarkable in vivo outcomes of angiogenesis and osseointegration were revealed by the subcutaneous implant model and bone tissue implant model in diabetic rats, respectively. The in vitro and in vivo results demonstrated that modified PEEK with multifunction can be an attractive tool for enhancing bone integration under diabetic conditions, underpinning the clinical application potential of modified implants for diabetic osseointegration.

Metal-Organic Framework-Derived Carbon as a Photoacoustic Modulator of Alzheimer's β-Amyloid Aggregate Structure

Photoacoustic materials emit acoustic waves into the surrounding by absorbing photon energy. In an aqueous environment, light-induced acoustic waves form cavitation bubbles by altering the localized pressure to trigger the phase transition of liquid water into vapor. In this study, we report photoacoustic dissociation of beta-amyloid (Aβ) aggregates, a hallmark of Alzheimer's disease, by metal-organic framework-derived carbon (MOFC). MOFC exhibits a near-infrared (NIR) light-responsive photoacoustic characteristic that possesses defect-rich and entangled graphitic layers that generate intense cavitation bubbles by absorbing tissue-penetrable NIR light. According to our video analysis, the photoacoustic cavitation by MOFC occurs within milliseconds in the water, which was controllable by NIR light dose. The photoacoustic cavitation successfully transforms robust, β-sheet-dominant neurotoxic Aβ aggregates into nontoxic debris by changing the asymmetric distribution of water molecules around the Aβ's amino acid residues. This work unveils the therapeutic potential of NIR-triggered photoacoustic cavitation as a modulator of the Aβ aggregate structure.

Multifunctional Carbon-Dot-Photosensitizer Nanoassemblies for Inhibiting Amyloid Aggregates, Suppressing Microbial Infection, and Overcoming the Blood-Brain Barrier

Amyloid aggregation, microbial infection, and the blood-brain barrier (BBB) are considered critical obstructions for the treatment of Alzheimer's disease (AD). At present, existing treatment strategies are rarely able to overcome these critical factors. Herein, we propose an innovative treatment strategy and design multifunctional nanoassemblies (yCDs-Ce6) from coassembling photosensitizers (chlorine e6) and yellow fluorescent carbon dots, which endow yCDs-Ce6 with the functions for photodynamic and photothermal therapy (PDT and PTT). Compared with reported inhibitors, yCDs-Ce6 can suppress amyloid aggregation for 7 days, disaggregate aggregates, reduce amyloid aggregation-induced cytotoxicity, and prevent microbial growth by PDT and PTT. Moreover, yCDs-Ce6 can specifically target amyloid aggregates and visually label amyloid aggregates. yCDs-Ce6 can also cross the BBB upon near-infrared light irradiation and clear amyloid deposition in APP/PS1 mice by PDT and PTT. Meanwhile, yCDs-Ce6 did not cause significant negative effects on normal cells or tissues. Based on the methods of PPT and PTT treatment, the research deeply explores the effect of the novel nanoassemblies on two hypotheses of AD, opening a novel therapeutic paradigm for research amyloid-related diseases.

Excited-State Intramolecular Hydrogen Transfer of Compact Molecules Controls Amyloid Aggregation Profiles

Developing chemical methodologies to directly modify harmful biomolecules affords the mitigation of their toxicity by persistent changes in their properties and structures. Here we report compact photosensitizers composed of the anthraquinone (AQ) backbone that undergo excited-state intramolecular hydrogen transfer, effectively oxidize amyloidogenic peptides, and, subsequently, alter their aggregation pathways. Density functional theory calculations showed that the appropriate position of the hydroxyl groups in the AQ backbone and the consequent intramolecular hydrogen transfer can facilitate the energy transfer to triplet oxygen. Biochemical and biophysical investigations confirmed that these photoactive chemical reagents can oxidatively vary both metal-free amyloid-β (Aβ) and metal-bound Aβ, thereby redirecting their on-pathway aggregation into off-pathway as well as disassembling their preformed aggregates. Moreover, the in vivo histochemical analysis of Aβ species produced upon photoactivation of the most promising candidate demonstrated that they do not aggregate into oligomeric or fibrillar aggregates in the brain. Overall, our combined computational and experimental studies validate a light-based approach for designing small molecules, with minimum structural complexity, as chemical reagents targeting and controlling amyloidogenic peptides associated with neurodegenerative disorders.

Comprehensive analysis reveals a 5-gene signature and immune cell infiltration in Alzheimer’s disease with qPCR validation

Over 50 million people around the world currently are suffering from Alzheimer’s disease (AD) without any effective therapy. Neuroinflammation plays a pivotal role in AD, which leads us to probe the profile of immune cell infiltration in AD. Here, we analyzed a microarray dataset (GSE44770) containing 115 AD and 115 control samples to determine biomarkers and immune infiltration characteristics of AD by multiple bioinformatics methods. First, we identified 3,840 DEGs (1892 upregulated and 1948 downregulated) by using the limma package and 2,697 hub genes by constructing a weighted gene correlation network, and they had a total of 2,167 intersecting genes. Second, combining the LASSO logistic regression and SVM-RFE, we obtained five biomarkers (DGKG, MAP3K7IP2, NFKBIE, VIP, and PCCB), which may reveal the key pathogenetic features of AD and serve as diagnostic markers assessed by the ROC curve (AUC = 0.9716) and validation of another AD dataset (GSE33000) (AUC = 0.9388). Third, immune cell infiltration analysis revealed that compared with control samples, plasma cells, CD8 T cells, T follicular helper cells, and activated NK cells infiltrated less in AD; Monocytes, M2 macrophages, and neutrophils infiltrated more in AD. Neutrophils and activated NK cells demonstrated the most significant and negative correlation. Then, Spearman correlation analysis between the five biomarkers and immune infiltrating cells revealed that all of them were significantly associated with plasma cells. Finally, mRNA levels of VIP and PCCB were conformed in a murine AD model. In conclusion, DGKG, MAP3K7IP2, NFKBIE, VIP, and PCCB may be used as diagnostic markers of AD, and the disruption of the delicate immune balance may be a key process in the onset and development of AD.

Functionalization strategies of polymeric nanoparticles for drug delivery in Alzheimer’s disease: Current trends and future perspectives

Alzheimer’s disease (AD), the most common form of dementia, is a progressive and multifactorial neurodegenerative disorder whose primary causes are mostly unknown. Due to the increase in life expectancy of world population, including developing countries, AD, whose incidence rises dramatically with age, is at the forefront among neurodegenerative diseases. Moreover, a definitive cure is not yet within reach, imposing substantial medical and public health burdens at every latitude. Therefore, the effort to devise novel and effective therapeutic strategies is still of paramount importance. Genetic, functional, structural and biochemical studies all indicate that new and efficacious drug delivery strategies interfere at different levels with various cellular and molecular targets. Over the last few decades, therapeutic development of nanomedicine at preclinical stage has shown to progress at a fast pace, thus paving the way for its potential impact on human health in improving prevention, diagnosis, and treatment of age-related neurodegenerative disorders, including AD. Clinical translation of nano-based therapeutics, despite current limitations, may present important advantages and innovation to be exploited in the neuroscience field as well. In this state-of-the-art review article, we present the most promising applications of polymeric nanoparticle-mediated drug delivery for bypassing the blood-brain barrier of AD preclinical models and boost pharmacological safety and efficacy. In particular, novel strategic chemical functionalization of polymeric nanocarriers that could be successfully employed for treating AD are thoroughly described. Emphasis is also placed on nanotheranostics as both potential therapeutic and diagnostic tool for targeted treatments. Our review highlights the emerging role of nanomedicine in the management of AD, providing the readers with an overview of the nanostrategies currently available to develop future therapeutic applications against this chronic neurodegenerative disease.

Wearable SERS Sensor Based on Omnidirectional Plasmonic Nanovoids Array with Ultra-High Sensitivity and Stability

Surface-enhanced Raman spectroscopy (SERS) is a promising technology for wearable sensors due to its fingerprint spectrum and high detection sensitivity. However, since SERS-activity is sensitive to both the distribution of "hotspots" and excitation angle, it is profoundly challenging to develop a wearable SERS sensor with high stability under various deformations during movements. Herein, inspired by omnidirectional light-harvesting of the compound eye of Xenos Peckii, a wearable SERS sensor is developed using omnidirectional plasmonic nanovoids array (OPNA), which is prepared by assembling a monolayer of metal nanoparticles into the artificial plasmonic compound-eye (APC). Specifically, APC is an interconnected frame containing omnidirectional "pockets" and acts as an "armour", not only rendering a broadband and omnidirectional enhancement of "hotspots" in the delicate nanoparticles array, but also maintaining an integrity of the "hotspots" against external mechanical deformations. Furthermore, an asymmetry super-hydrophilic pattern is fabricated on the surface of OPNA, endowing the hydrophobic OPNA with the ability to spontaneously extract and concentrate the analytes from sweat. Such an armored SERS sensor can enable the wearable and in situ analysis with high sensitivity and stability, exhibiting great potential in point-of-care analysis.

Transcriptomics Integrated with Metabolomics Reveals 2-Methoxy-1, 4-Naphthoquinone-Based Carbon Dots Induced Molecular Shifts in Penicillium italicum

Penicillium italicum (P. italicum), a citrus blue mold, is a pathogenic fungus that greatly affects the postharvest quality of citrus fruits with significant economic loss. Our previous research showed that 2-methoxy-1, 4-naphthoquinone (MNQ) inhibited the growth of Penicillium italicum. However, the water dispersibility of MNQ will limit its further application. Herein, we synthesized MNQ-based carbon dots (2−CDs) with better water dispersibility, which showed a potential inhibitory effect on P. italicum (MIC = 2.8 μg/mL) better than that of MNQ (MIC = 5.0 μg/mL). Transcriptomics integrated with metabolomics reveals a total of 601 differentially enriched genes and 270 differentially accumulated metabolites that are co-mapped as disruptive activity on the cell cytoskeleton, glycolysis, and histone methylation. Furthermore, transmission electron microscopy analysis showed normal appearances and intracellular septum of P. italicum after treatment. These findings contribute tofurther understanding of the possible molecular action of 2−CDs.

Controlled and Selective Photo-oxidation of Amyloid-β Fibrils by Oligomeric p-Phenylene Ethynylenes

Photodynamic therapy (PDT) has been explored as a therapeutic strategy to clear toxic amyloid aggregates involved in neurodegenerative disorders such as Alzheimer's disease. A major limitation of PDT is off-target oxidation, which can be lethal for the surrounding cells. We have shown that a novel class of oligo-p-phenylene ethynylenes (OPEs) exhibit selective binding and fluorescence turn-on in the presence of prefibrillar and fibrillar aggregates of disease-relevant proteins such as amyloid-β (Aβ) and α-synuclein. Concomitant with fluorescence turn-on, OPE also photosensitizes singlet oxygen under illumination through the generation of a triplet state, pointing to the potential application of OPEs as photosensitizers in PDT. Herein, we investigated the photosensitizing activity of an anionic OPE for the photo-oxidation of Aβ fibrils and compared its efficacy to the well-known but nonselective photosensitizer methylene blue (MB). Our results show that, while MB photo-oxidized both monomeric and fibrillar conformers of Aβ40, OPE oxidized only Aβ40 fibrils, targeting two histidine residues on the fibril surface and a methionine residue located in the fibril core. Oxidized fibrils were shorter and more dispersed but retained the characteristic β-sheet rich fibrillar structure and the ability to seed further fibril growth. Importantly, the oxidized fibrils displayed low toxicity. We have thus discovered a class of novel theranostics for the simultaneous detection and oxidization of amyloid aggregates. Importantly, the selectivity of OPE's photosensitizing activity overcomes the limitation of off-target oxidation of traditional photosensitizers and represents an advancement of PDT as a viable strategy to treat neurodegenerative disorders.

Enhancing autophagy in Alzheimer's disease through drug repositioning

Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.

Inhibiting protein aggregation with nanomaterials: The underlying mechanisms and impact factors

Protein aggregation is correlated with the onset and progression of protein misfolding diseases (PMDs). Inhibiting the generation of toxic aggregates of misfolded proteins has been proposed as a therapeutic approach for PMDs. Due to their unique properties, nanomaterials have been extensively investigated for their ability to inhibit protein aggregation and have shown great potential in the diagnosis and treatment of PMDs. However, the precise mechanisms by which nanomaterials interact with amyloidogenic proteins and the factors influencing these interactions remain poorly understood. Consequently, developing a rational design strategy for nanomaterials that target specific proteins in PMDs has been challenging. In this review, we elucidate the effects of nanomaterials on protein aggregation and describe the mechanisms through which nanomaterials interfere with protein aggregation. The major factors impacting protein-nanomaterial interaction such as size, charge, concentration, surface modification and morphology that can be rationally addressed to achieve the desired effects of nanomaterials on protein aggregation are summarized. The prospects and challenges to the clinical application of nanomaterials for the treatment of PMDs are also discussed.

Current progress in aptamer-based sensing tools for ultra-low level monitoring of Alzheimer's disease biomarkers

Alzheimer's disease (AD) as common late-life dementia is pathologically associated with the irreversible and progressive disorder, misfolding, deposition, and accumulation of the brain proteins. Especially, the formation of fibrous amyloid plaques by aggregation of amyloid-β peptides is the pathological cause of this neurologic disorder disease. Besides, tau protein isoforms destabilize the microtubule filaments through post-translational modifications and induce nerve cells' death. Amyloid-β peptides and tau proteins are considered as the critical symptom and reliable molecular biomarkers for the early diagnosis of AD. AD is characterized by impaired thinking proficiencies, cognitive decline, memory loss, and behavioral disability. Since there is no efficacious therapy for AD at present, the development of precise sensing tools for the early diagnosis of this disease is essential and crucial. Aptamer-based biosensors (aptasensors) have acquired utmost importance in the field of AD healthcare, due to excellent sensitivity and specificity, ease-of-use, cost-effectiveness, portability, and rapid assay time. Here, we highlight the recent developments and novel perspectives in the field of aptasensor design to quantitatively monitor the AD biomarkers. Finally, some results are represented to achieve a promising viewpoint for introducing the novel aptasensor test kits in the future.

A multifunctional chemical toolbox to engineer carbon dots for biomedical and energy applications

Photoluminescent carbon nanoparticles, or carbon dots, are an emerging class of materials that has recently attracted considerable attention for biomedical and energy applications. They are defined by characteristic sizes of <10 nm, a carbon-based core and the possibility to add various functional groups at their surface for targeted applications. These nanomaterials possess many interesting physicochemical and optical properties, which include tunable light emission, dispersibility and low toxicity. In this Review, we categorize how chemical tools impact the properties of carbon dots. We look for pre- and postsynthetic approaches for the preparation of carbon dots and their derivatives or composites. We then showcase examples to correlate structure, composition and function and use them to discuss the future development of this class of nanomaterials.

Light-Stimulated Carbon Dot Hydrogel: Targeting and Clearing Infectious Bacteria In Vivo

Infectious bacteria evolve fast into resistance to conventional antimicrobial agents, whereas treatments for drug resistance bacteria progress more slowly. Here, we report a universally applicable photoactivated antimicrobial modality through light-responsive carbon dot-embedding soft hyaluronic acid hydrogel (CDgel). Because of the innate nature of the infectious bacteria that produce hyaluronidase, applied hyaluronic acid-based CDgel breaks down via bacteria and releases carbon dots (CDs) into the infectious sites. The released CDs possess photodynamic capabilities under light irradiation, inducing ¹O₂ generation and growth inhibition of the infectious bacteria, S. aureus and E. coli (∼99% and ∼97%, respectively), in vitro. In particular, these photodynamic effects of CDs from CDgel have been shown to accelerate the healing of infected wounds in vivo, showing a higher wound regeneration rate as compared to that of untreated wounds. Our work demonstrates that the biocompatible and shape-controllable CDgel possesses therapeutic potential as a treatment modality for the light-driven control of drug-resistant bacterial infections.

Synthesis of carbon dots with strong luminescence in both dispersed and aggregated states by tailoring sulfur doping

Carbon dots (CDots), a class of environmentally friendly carbon-based luminescent nanomaterial, have been applied in a wide variety of fields, including bioimaging and light-emitting diodes (LEDs). Prior to these applications, however, CDots usually require modifications because some of its limitations (e.g., the aggregation-induced luminescence quenching) make it difficult to apply in solid state. In order to realize CDots-based multiple applications simultaneously, this paper examines how CDots with a strong greenish-yellow fluorescence in both dispersed and aggregated states are prepared by microwave-assisted heating salicylic acid and thiourea. Based on control testing and the analysis of density functional theory calculations, S element from thiourea is doped into CDots and proves to be critical in governing the photoluminescence (PL) emission color. Featured with excellent biocompatibility and photostability, the dispersed CDots with photoluminescence quantum yields (32%) are able to function as a biological imaging reagent in vitro and in vivo without any side effect. Furthermore, the aggregated CDots also exhibit high photoluminescence quantum yields (26%) and remarkable resistance to organic solvent. These advantages will ensure that S-doped CDots can be applied as a color conversion layer so that white LEDs with different Commission International de L'Eclariage coordinates and tunable color temperature can be fabricated.

Dual-targeted carbon-dot-drugs nanoassemblies for modulating Alzheimer's related amyloid-β aggregation and inhibiting fungal infection

Amyloid aggregation and fungal infection, especially amyloid beta (Aβ) peptide and Candida albicans are considered as two of the crucial pathogenic agents in Alzheimer's disease (AD). In this work, we propose an innovative treatment strategy for AD, targeting at not only Aβ aggregation but also Candida albicans infection. Here, a high-performance nanomaterial, namely gCDs-E, have been prepared by self-assembled of glycosylated carbon dots (gCDs) and epigallocatechin-3-gallate (EGCG). Surprisingly, gCDs-E can not only suppress the fibrillation of Aβ and disaggregate Aβ fibrils, but also effectively inhibit the activity of Candida albicans. More importantly, the prepared gCDs-E can effectively cut down the cytotoxicity of amyloid aggregations, and the cell viability reached to 99.2%. In addition, the capability of the gCDs-E for blood brain barrier (BBB) penetration was also observed using a normal mice model. Above all, the gCDs-E greatly cleaned Aβ deposition and improved memory impairment in APP/PS1 transgenic AD model mice, confirming its potential as therapeutic agent for AD treatment.

Boronate carbon nanoparticles featuring efficient FRET for activatable two-photon fluorescence imaging of sialic acid surface-abundant tumor cells

Two-photon carbon-based nanoprobes hold great potential for biomedical applications as a result of their advantages of low fluorescence background, deep tissue imaging penetration and enhanced spatial resolution. However, the development of an activatable two-photon fluorescence carbon-based nanoprobe that simultaneously has the ability to target desired organs or cells is highly desired but remained a largely unsolved challenge. Herein, we developed boronate affinity BCNP@MnO2 nanocomposites, constructed by one step in situ growth of MnO2 nanosheets on the surface of aminophenylboronic acid-functionalized CNPs (BCNPs) via a redox reaction, which can feature efficient fluorescence energy transfer quenching to the BCNPs, allowing for tumor-specific affinity recognition and two-photon fluorescence activation imaging. By utilizing the inherent two-photon optical properties and sialic acid (SA) specific targeting ability of the BCNPs, good biocompatibility of the nanocomposites as well as highly sensitive and selective responses of MnO2 nanosheets towards GSH, the developed nanocomposites have demonstrated specific two-photon fluorescence activation imaging in target cancer cells and nude mouse tissues. Therefore, our proposed novel strategy could be used for monitoring GSH-triggered two-photon fluorescence activation events in SA-overexpressed cancer cells and has promising applications in both biological exploration and clinical diagnosis.