Carbon nitride-based nanocaptor: An intelligent nanosystem with metal ions chelating effect for enhanced magnetic targeting phototherapy of Alzheimer's disease

Recent Advances in Targeting Transition Metals (Copper, Iron, and Zinc) in Alzheimer's Disease

Changes in the transition metal homeostasis in the brain are closely linked with Alzheimer's disease (AD), including intraneuronal iron accumulation and extracellular copper and zinc pooling in the amyloid plague. The brain copper, zinc, and iron surplus are commonly acknowledged characteristics of AD, despite disagreements among some. This has led to the theory that oxidative stress resulting from abnormal homeostasis of these transition metals may be a causative explanation behind AD. In the nervous system, the interaction of metals with proteins appears to be an essential variable in the development or suppression of neurodegeneration. Chelation treatment may be an option for treating neurodegeneration induced by transition metal ion dyshomeostasis. Some clinicians even recommend using chelating agents as an adjunct therapy for AD. The current review also looks at the therapeutic strategies that have been attempted, primarily with metal-chelating drugs. Metal buildup in the nervous system, as reported in the AD, could be the result of compensatory mechanisms designed to improve metal availability for physiological functions.

Aβ42 and ROS dual-targeted multifunctional nanocomposite for combination therapy of Alzheimer's disease

Amyloid-β (Aβ) readily misfolds into neurotoxic aggregates, generating high levels of reactive oxygen species (ROS), leading to progressive oxidative damage and ultimately cell death. Therefore, simultaneous inhibition of Aβ aggregation and scavenging of ROS may be a promising therapeutic strategy to alleviate Alzheimer's disease pathology. Based on the previously developed antibody 1F12 that targets all forms of Aβ42, we developed an Aβ42 and ROS dual-targeting nanocomposite using biodegradable mesoporous silica nanoparticles as carriers to load ultra-small cerium oxide nanocrystals (bMSNs@Ce-1F12). By modifying the brain-targeted rabies virus glycoprotein 29 (RVG29-bMSNs@Ce-1F12), this intelligent nanocomposite can efficiently target brain Aβ-rich regions. Combined with peripheral and central nervous system treatments, RVG29-bMSNs@Ce-1F12 can significantly alleviate AD symptoms by inhibiting Aβ42 misfolding, accelerating Aβ42 clearance, and scavenging ROS. Furthermore, this synergistic effect of ROS scavenging and Aβ clearance exhibited by this Aβ42 and ROS dual-targeted strategy also reduced the burden of hyperphosphorylated tau, alleviated glial cell activation, and ultimately improved cognitive function in APP/PS1 mice. Our findings indicate that RVG29-bMSNs@Ce-1F12 is a promising nanodrug that can facilitate multi-target treatment of AD.

Chitosan/PLA-loaded Magnesium oxide nanocomposite to attenuate oxidative stress, neuroinflammation and neurotoxicity in rat models of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloid-beta (Aβ) aggregation, neuroinflammation, oxidative stress, and dysfunction in the mitochondria and cholinergic system. In this study, the synthesis of chitosan-polylactic acid-loaded magnesium oxide nanocomposite (CH/PLA/MgONCs) was examined using the green precipitation method. The synthesized CH/PLA/MgONCs were confirmed by using the UV-Vis spectrum, FT-IR, SEM-EDAX, and physical properties. The experiments were carried out using male Wistar rats by injecting streptozotocin (STZ) bilaterally into the brain's ventricles through the intracerebroventricular (ICV) route at a dose of 3 mg/kg. We also evaluated the effects of CH/PLA/MgONCs at doses of 10 mg/kg. To assess the cognitive dysfunction induced by ICV-STZ, we performed behavioral, biochemical, and histopathological analyses. In our study results, UV-Vis spectrum analysis of CH/PLA/MgONCs showed 285 nm, FT-IR analyses confirmed that the various functional groups were present, and SEM-EDAX analysis confirmed that a cauliflower-like spherical shape, Mg and O were present. Treatment with CH/PLA/MgONCs (10 mg/kg) showed a significant improvement in spatial and non-spatial memory functions. This was further supported by biochemical analysis showing improved antioxidant enzyme (GSH, SOD, CAT, and GPx activity) activities that significantly attenuated cholinergic activity and oxidative stress. In the CH/PLA/MgONCs-treated group, significant improvement was observed in the mitochondrial complex activity. ICV-STZ-induced neuroinflammation, as indicated by increased levels of TNF-α, IL-6, and CRP, was significantly reduced by CH/PLA/MgONCs treatment. Additionally, CH/PLA/MgONCs treated histological results showed improved healthy neuronal cells in the brain. Furthermore, in silico studies confirm that these molecules have good binding affinity and inhibit Aβ aggregation. In conclusion, CH/PLA/MgONCs treatment reversed AD pathology by improving memory and reducing oxidative stress, neuroinflammation, and mitochondrial dysfunction. These findings recommend that CH/PLA/MgONCs are possible therapeutic agents to treat AD.

Micro/nanosystems for controllable drug delivery to the brain

Drug delivery to the brain is crucial in the treatment for central nervous system disorders. While significant progress has been made in recent years, there are still major challenges in achieving controllable drug delivery to the brain. Unmet clinical needs arise from various factors, including controlled drug transport, handling large drug doses, methods for crossing biological barriers, the use of imaging guidance, and effective models for analyzing drug delivery. Recent advances in micro/nanosystems have shown promise in addressing some of these challenges. These include the utilization of microfluidic platforms to test and validate the drug delivery process in a controlled and biomimetic setting, the development of novel micro/nanocarriers for large drug loads across the blood-brain barrier, and the implementation of micro-intervention systems for delivering drugs through intraparenchymal or peripheral routes. In this article, we present a review of the latest developments in micro/nanosystems for controllable drug delivery to the brain. We also delve into the relevant diseases, biological barriers, and conventional methods. In addition, we discuss future prospects and the development of emerging robotic micro/nanosystems equipped with directed transportation, real-time image guidance, and closed-loop control.

Silicon-Carbon Dots-Loaded Mesoporous Silica Nanocomposites (mSiO2@SiCDs): An Efficient Dual Inhibitor of Cu2+-Mediated Oxidative Stress and Aβ Aggregation for Alzheimer's Disease

The redox-active metal ions, especially Cu2+, are highly correlated to Alzheimer's disease (AD) by causing metal ion-mediated oxidative stress and toxic metal-bound β-amyloid (Aβ) aggregates. Numerous pieces of evidence have revealed that the regulation of metal homeostasis could be an effective therapeutic strategy for AD. Herein, in virtue of the interaction of both amino-containing silane and ethylenediaminetetraacetic acid disodium salt for Cu2+, the silicon-carbon dots (SiCDs) are deliberately prepared using these two raw materials as the cocarbon source; meanwhile, to realize the local enrichment of SiCDs and further maximize the chelating ability to Cu2+, the SiCDs are feasibly loaded to the biocompatible mesoporous silica nanoparticles (mSiO2) with the interaction between residual silane groups on SiCDs and silanol groups of mSiO2. Thus-obtained nanocomposites (i.e., mSiO2@SiCDs) could serve as an efficient Cu2+ chelator with satisfactory metal selectivity and further modulate the enzymic activity of free Cu2+ and the Aβ42-Cu2+ complex to alleviate the pathological oxidative stress with an anti-inflammatory effect. Besides, mSiO2@SiCDs show an inspiring inhibitory effect on Cu2+-mediated Aβ aggregation and further protect the neural cells against the toxic Aβ42-Cu2+ complex. Moreover, the transgenic Caenorhabditis elegans CL2120 assay demonstrates the protective efficacy of mSiO2@SiCDs on Cu2+-mediated Aβ toxicity in vivo, indicating its potential for AD treatment.

Ameliorative effects of pine nut peptide-zinc chelate (Korean pine) on a mouse model of Alzheimer's disease

In this study, 50 SD adult male mice were used to create an Alzheimer's disease model. The mice's learning and memory abilities were evaluated using an eight-arm radial maze experiment, and changes in body weight and food intake were noted. This helped to better validate the improvement of Alzheimer's disease caused by pine nut peptide-zinc chelate (Korean pine). For a more thorough investigation, mice's brains were dissected, Endogenous mercaptan antioxidants (enzymes), which are markers of brain tissue, were assessed, and mouse gut flora was analyzed. The findings demonstrated that pine nut peptide-zinc chelate (Korean pine) can improve learning and memory, stop brain aging and damage, and control gut flora in mice. It may exert its effects by ameliorating decreased AChE levels and increased ChAT levels in the central cholinergic system, endogenous thiol antioxidants (enzymes) in the cerebral cortex, and by controlling the bacterial flora in the gut.

Posterity of nanoscience as lipid nanosystems for Alzheimer's disease regression

Alzheimer's disease (AD) is a type of dementia that affects a vast number of people around the world, causing a great deal of misery and death. Evidence reveals a relationship between the presence of soluble Aβ peptide aggregates and the severity of dementia in Alzheimer's patients. The BBB (Blood Brain Barrier) is a key problem in Alzheimer's disease because it prevents therapeutics from reaching the desired places. To address the issue, lipid nanosystems have been employed to deliver therapeutic chemicals for anti-AD therapy in a precise and targeted manner. The applicability and clinical significance of lipid nanosystems to deliver therapeutic chemicals (Galantamine, Nicotinamide, Quercetin, Resveratrol, Curcumin, HUPA, Rapamycin, and Ibuprofen) for anti-AD therapy will be discussed in this review. Furthermore, the clinical implications of the aforementioned therapeutic compounds for anti-AD treatment have been examined. Thus, this review will pave the way for researchers to fashion therodiagnostics approaches based on nanomedicine to overcome the problems of delivering therapeutic molecules across the blood brain barrier (BBB).

A biosensor based on Fe3O4@MXene-Au nanocomposites with high peroxidase-like activity for colorimetric and smartphone-based detection of glucose

A novel magnetic nanozyme Fe₃O₄@MXene-Au nanocomposite, which possessed higher peroxidase-like activity than that of Fe₃O₄ nanoparticles and Fe₃O₄@MXene nanocomposites, was developed. The outstanding magnetic properties of the nanozyme endowed it with the ability of simple and rapid separation, achieving great recyclability. Based on Fe₃O₄@MXene-Au nanocomposites and glucose oxidase (Glu Ox), a highly selective colorimetric biosensor for glucose detection was developed. Fe₃O₄@MXene-Au nanocomposites can catalyze H₂O₂ produced from glucose catalyzed by glucose oxidase to ·OH and oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) with a significant absorbance at 652 nm. The linear range of glucose was 0-1.4 mM under optimal conditions, with a limit of detection (LOD) of 0.11 mM. Glucose in human whole blood was successfully detected with satisfactory recoveries. Furthermore, a facile agarose hydrogel detection platform was designed. With smartphone software, glucose detection can be realized by the agarose hydrogel platform, demonstrating the potential in on-site and visual detection of glucose.

Functionalised penetrating peptide-chondroitin sulphate‑gold nanoparticles: Synthesis, characterization, and applications as an anti-Alzheimer's disease drug

The purpose of this study was to construct a transmembrane peptide-chondroitin sulphate‑gold nanoparticle (TAT-CS@Au) delivery system and investigate its activity as an anti-Alzheimer's disease (AD) drug. We successfully prepared TAT-CS@Au nanoparticles, investigated their anti-AD effects, and explored the possible mechanisms in in vitro models. TAT-CS@Au exhibited excellent cellular uptake and transport capacity, effectively inhibited the accumulation of Aβ_1-40, and significantly reduced Aβ_1-40-induced apoptosis in SH-SY5Y cells. Furthermore, TAT-CS@Au significantly reduced oxidative stress damage and cholinergic injury induced by Aβ_1-40 by regulating intracellular concentrations of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and acetylcholine (ACh). Western blotting results demonstrated that TAT-CS@Au inhibited aberrant tau phosphorylation (Ser199, Thr205, Ser404, and Ser396) through GSK3β inactivation. TAT-CS@Au decreased the levels of inflammatory factors, specifically TNF-α, IL-6, and IL-1β, by inhibiting NF-κB nuclear translocation by activating MAPK signalling pathways. Overall, these results indicate that TAT-CS@Au exhibits excellent transmembrane ability, inhibits Aβ_1-40 accumulation, antagonises oxidative stress, reduces aberrant tau phosphorylation, and suppresses the expression of inflammatory factors. TAT-CS@Au may be a multi-target anti-AD drug with good cell permeability, providing new insights into the design and research of anti-AD therapeutics.

An NIR-Driven Upconversion/C3N4/CoP Photocatalyst for Efficient Hydrogen Production by Inhibiting Electron-Hole Pair Recombination for Alzheimer's Disease Therapy

Redox imbalance and abnormal amyloid protein (Aβ) buildup are key factors in the etiology of Alzheimer's disease (AD). As an antioxidant, the hydrogen molecule (H₂) has the potential to cure AD by specifically scavenging highly harmful reactive oxygen species (ROS) such as ^•OH. However, due to the low solubility of H₂ (1.6 ppm), the traditional H₂ administration pathway cannot easily achieve long-term and effective accumulation of H₂ in the foci. Therefore, how to achieve the continuous release of H₂ in situ is the key to improve the therapeutic effect on AD. As a corollary, we designed a rare earth ion doped g-C₃N₄ upconversion photocatalyst, which can respond to NIR and realize the continuous production of H₂ by photocatalytic decomposition of H₂O in biological tissue, which avoids the problem of the poor penetration of visible light. The introduction of CoP cocatalyst accelerates the separation and transfer of photogenerated electrons in g-C₃N₄, thus improving the photocatalytic activity of hydrogen evolution reaction. The morphology of the composite photocatalyst was shown by transmission electron microscopy, and the crystal structure was studied by X-ray diffractometry and Raman analysis. In addition, the ability of g-C₃N₄ to chelate metal ions and the photothermal properties of CoP can inhibit Aβ and reduce the deposition of Aβ in the brain. Efficient in situ hydrogen production therapy combined with multitarget synergism solves the problem of a poor therapeutic effect of a single target. In vivo studies have shown that UCNP@CoP@g-C₃N₄ can reduce Aβ deposition, improve memory impairment, and reduce neuroinflammation in AD mice.

A Cu+ /Thiourea Dendrimer Achieves Excellent Cytosolic Protein Delivery via Enhanced Cell Uptake and Endosome Escape

Intracellular protein delivery has attracted considerable attention in the development of protein-based therapeutics, however, the design of highly efficient materials for robust delivery of native proteins remains challenging. This study proposes a Cu⁺ -based coordination polymer for cytosolic protein delivery with high efficacy and robustness. The phenylthiourea grafted dendrimer is coordinated with cuprous ions to prepare the polymeric carrier, which efficiently bind cargo proteins via a combination of coordination, ionic and hydrophobic interactions. The incorporation of Cu⁺ ions in the polymer greatly improves its cellular uptake and endosomal escape. The cuprous-based coordination polymer successfully delivered a variety of structurally diverse proteins into various cell lines with reserved bioactivities. This study provides a new type of coordination polymers for cytosolic delivery of biomacromolecules.

Molecular mechanisms of Alzheimer's disease: From therapeutic targets to promising drugs

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment so widespread that it interferes with a person's ability to complete daily activities. AD is becoming increasingly common, and it is estimated that the number of patients will reach 152 million by 2050. Current treatment options for AD are symptomatic and have modest benefits. Therefore, considering the human, social, and economic burden of the disease, the development of drugs with the potential to alter disease progression has become a global priority. In this review, the molecular mechanisms involved in the pathology of AD were evaluated as therapeutic targets. The main aim of the review is to focus on new knowledge about mitochondrial dysfunction, oxidative stress, and neuronal transmission in AD, as well as a range of cellular signaling mechanisms and associated treatments. Important molecular interactions leading to AD were described in amyloid cascade and in tau protein function, oxidative stress, mitochondrial dysfunction, cholinergic and glutamatergic neurotransmission, cAMP-regulatory element-binding protein (CREB), the silent mating type information regulation 2 homolog 1 (SIRT-1), neuroinflammation (glial cells), and synaptic alterations. This review summarizes recent experimental and clinical research in AD pathology and analyzes the potential of therapeutic applications based on molecular disease mechanisms.

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.

NIR-Assisted MgO-Based Polydopamine Nanoparticles for Targeted Treatment of Parkinson's Disease through the Blood-Brain Barrier

The blood-brain barrier (BBB) is a major limiting factor that prevents the treatment of Parkinson's disease (PD). In the present study, MgOp@PPLP nanoparticles are explored by using MgO nanoparticles as a substrate, polydopamine as a shell, wrapping anti-SNCA plasmid inside, and modifying polyethylene glycol, lactoferrin, and puerarin on the surface to improve the hydrophilicity, brain targeting and antioxidant properties of the particles, respectively. MgOp@PPLP exhibits superior near-infrared radiation (NIR) response. Under the guidance of photothermal effect, these MgOp@PPLP particles are capable of penetrating the BBB and be taken up by neuronal cells to exert gene therapy and antioxidant therapy. In both in vivo and in vitro models of PD, MgOp@PPLP exhibits good neuroprotective effects. Therefore, combined with noninvasive NIR radiation, MgOp@PPLP nanoplatform with good biocompatibility becomes an ideal material to combat neurodegenerative diseases.

Prospects for the next generation of artificial enzymes for ensuring the quality of chilled meat: Opportunities and challenges

As living standards rise, the demand for high-quality chilled meat among consumers also grows. Researchers and enterprises have been interested in ensuring the quality of chilled meat in all links of the downstream industry. Nanozyme has shown the potential to address the aforementioned requirements. Reasons and approaches for the application of nanozymes in the freshness assessment or shelf life extension of chilled meat were discussed. The challenges for applying these nanozymes to ensure the quality of chilled meat were also summarized. Finally, this review examined the safety, regulatory status, and consumer attitudes toward nanozymes. This review revealed that the freshness assessment of chilled meat is closely related to mimicking the enzyme activities of nanozymes, whereas the shelf life changes of chilled meat are mostly dependent on the photothermal activities and pseudophotodynamic activities of nanozymes. In contrast, studies regarding the shelf life of chilled meat are more challenging to develop, as excessive heat or reactive oxygen species impair its quality. Notably, meat contains a complex matrix composition that may interact with the nanozyme, reducing its effectiveness. Nanopollution and mass manufacturing are additional obstacles that must be overcome. Therefore, it is vital to choose suitable approaches to ensure meat quality. Furthermore, the safety of nanozymes in meat applications still needs careful consideration owing to their widespread usage.

Chondroitin Sulfate-Based Cryogels for Biomedical Applications

Cryogels attained from natural materials offer exceptional properties in applications such as tissue engineering. Moreover, Halloysite Nanotubes (HNT) at 1:0.5 weight ratio were embedded into CS cryogels to render additional biomedical properties. The hemolysis index of CS cryogel and CS:HNT cryogels was calculated as 0.77 ± 0.41 and 0.81 ± 0.24 and defined as non-hemolytic materials. However, the blood coagulation indices of CS cryogel and CS:HNT cryogels were determined as 76 ± 2% and 68 ± 3%, suggesting a mild blood clotting capability. The maximum% swelling capacity of CS cryogel was measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, at pH 1.0, pH 7.4 and pH 9.0, respectively, which were reduced to 1961 ± 288%, 2816 ± 192, 2405 ± 73%, respectively, for CS:HNT cryogel. It was found that CS cryogels can hydrolytically be degraded 41 ± 1% (by wt) in 16-day incubation, whereas the CS:HNT cryogels degraded by 30 ± 1 wt %. There is no chelation for HNT and 67.5 ± 1% Cu(II) chelation for linear CS was measured. On the other hand, the CS cryogel and CS:HNT cryogel revealed Cu(II) chelating capabilities of 60.1 ± 12.5%, and 43.2 ± 17.5%, respectively, from 0.1 mg/mL Cu(II) ion stock solution. Additionally, at 0.5 mg/mL CS, CS:HNT, and HNT, the Fe(II) chelation capacity of 99.7 ± 0.6, 86.2 ± 4.7% and only 11.9 ± 4.5% were measured, respectively, while no Fe(II) was chelated by linear CS chelated Fe(II). As the adjustable and controllable swelling properties of cryogels are important parameters in biomedical applications, the swelling properties of CS cryogels, at different solution pHs, e.g., at the solution pHs of 1.0, 7.4 and 9.0, were measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, respectively, and the maximum selling% values of CS:HNT cryogels were determined as 1961 ± 288%, 2816 ± 192, 2405 ± 73%, respectively, at the same conditions. Alpha glucosidase enzyme interactions were investigated and found that CS-based cryogels can stimulate this enzyme at any CS formulation.

Near-Infrared Radiation-Assisted Drug Delivery Nanoplatform to Realize Blood-Brain Barrier Crossing and Protection for Parkinsonian Therapy

Mitochondrial dysfunction, which is directly involved in Parkinson's disease (PD), is characterized by the production of reactive oxygen species (ROS) and aberrant energy metabolism. Thus, regulating mitochondrial function might be an effective strategy to treat PD. However, the blood-brain barrier (BBB) presents a significant challenge for the intracerebral delivery of drugs. Here, we synthesized a zeolitic imidazolate framework 8-coated Prussian blue nanocomposite (ZIF-8@PB), which was encapsulated with quercetin (QCT), a natural antioxidant, to treat PD. ZIF-8@PB-QCT exhibited superior near-infrared radiation (NIR) response and penetrated through the BBB to the site of mitochondrial damage guided by the photothermal effect. In the mice model of PD, the QCT released from ZIF-8@PB-QCT significantly increased the adenosine triphosphate levels, reduced the oxidative stress levels, and reversed dopaminergic neuronal damage as well as PD-related behavioral deficits without any damage to the normal tissues. Furthermore, we explored the underlying neuroprotective mechanism of ZIF-8@PB-QCT that was mediated by activating the PI3K/Akt signaling pathway. Thus, combined with noninvasive NIR radiation, the biocompatible ZIF-8@PB-QCT nanocomposite could be used to treat neurodegenerative diseases.

Photothermal and Photodynamic Therapies via NIR-Activated Nanoagents in Combating Alzheimer's Disease

It is well established that the polymerization of amyloid-β peptides into fibrils/plaques is a critical step during the development of Alzheimer's disease (AD). Phototherapy, which includes photodynamic therapy and photothermal therapy, is a highly attractive strategy in AD treatment due to its merits of operational flexibility, noninvasiveness, and high spatiotemporal resolution. Distinct from traditional chemotherapies or immunotherapies, phototherapies capitalize on the interaction between photosensitizers or photothermal transduction agents and light to trigger photochemical reactions to generate either reactive oxygen species or heat effects to modulate Aβ aggregation, ultimately restoring nerve damage and ameliorating memory deficits. In this Review, we provide an overview of the recent advances in the development of near-infrared-activated nanoagents for AD phototherapies and discuss the potential challenges of and perspectives on this emerging field with a special focus on how to improve the efficiency and utility of such treatment. We hope that this Review will spur preclinical research and the clinical translation of AD treatment through phototherapy.

Nanomaterials for Modulating the Aggregation of β-Amyloid Peptides

The aberrant aggregation of amyloid-β (Aβ) peptides in the brain has been recognized as the major hallmark of Alzheimer's disease (AD). Thus, the inhibition and dissociation of Aβ aggregation are believed to be effective therapeutic strategiesforthe prevention and treatment of AD. When integrated with traditional agents and biomolecules, nanomaterials can overcome their intrinsic shortcomings and boost their efficiency via synergistic effects. This article provides an overview of recent efforts to utilize nanomaterials with superior properties to propose effective platforms for AD treatment. The underlying mechanismsthat are involved in modulating Aβ aggregation are discussed. The summary of nanomaterials-based modulation of Aβ aggregation may help researchers to understand the critical roles in therapeutic agents and provide new insight into the exploration of more promising anti-amyloid agents and tactics in AD theranostics.

Ultrasensitive Detection of Amyloid β Oligomers Based on the "DD-A" FRET Binary Probes and Quadrivalent Cruciform DNA Nanostructure-Mediated Cascaded Amplifier

The reported donor donor-acceptor ("DD-A") fluorescence resonance energy transfer (FRET) was typically achieved through random collisions and interactions of DNA molecules in the bulk solution, which has inevitable defects, including weak biological stability, slow reaction kinetics, and low hybridization efficiency. In order to overcome these deficiencies, this work developed a quadrivalent cruciform DNA nanostructure (qCDN)-mediated cascaded catalyzed hairpin assembly (CHA) amplifier for the fluorescence detection of amyloid β oligomer species (AβOs). First, four H1 and four H2 hairpins were assembled on one qCDN to obtain qCDNH1 and qCDNH2, respectively. In the presence of AβOs, strand C was released from the P1-C hybrid hairpin and then alternately opened qCDNH1 and qCDNH2 to trigger the qCDN-mediated CHA. As a result, double donors in H1 and one acceptor in H2 were mutually closed, and the porous DNA nanonet with a high loading of "DD-A" FRET binary probes was formed. The FRET efficiency was approximately 78%, and the initial reaction rate was 25-fold faster than the conventional CHA. The detection limit of AβOs was as low as 0.69 pM. The combination of the "DD-A" FRET binary probes and qCDN-mediated cascaded amplifier exhibited great promise for detecting biomarkers with trace levels.

New advances in brain-targeting nano-drug delivery systems for Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide and its incidence is increasing due to the ageing population. Currently, the main limitations of AD treatment are low blood-brain barrier permeability, severe off-target of drugs, and immune abnormality. In this review, four hypotheses for Alzheimer's pathogenesis and three challenges for Alzheimer's drug delivery are discussed. In addition, this article summarises the different strategies of brain targeting nano-drug delivery systems (NDDSs) developed in the last 10 years. These strategies include receptor-mediated (transferrin receptor, low-density lipoprotein receptor-related protein, lactoferrin receptor, etc.), adsorption-mediated (cationic, alkaline polypeptide, cell-penetrating peptides, etc.), and transporter-mediated (P-gp, GLUT1, etc.). Moreover, it provides insights into novel strategies used in AD, such as exosomes, virus-like particles, and cell membrane coating particles. Hence, this review will help researchers to understand the current progress in the field of NDDSs for the central nervous system and find new directions for AD therapy.HighlightsCharacteristics and challenges based on the pathogenesis of AD were discussed.Recent advances in novel brain-targeting NDDSs for AD over the past 10 years were summarised.

Photoresponsive materials for intensified modulation of Alzheimer's amyloid-β protein aggregation: A review

The abnormal self-assembly of amyloid-β protein (Aβ) into toxic aggregates is a major pathological hallmark of Alzheimer's disease (AD). Modulation of Aβ fibrillization with pharmacological modalities has become an active field of research, which aims to mitigate Aβ-induced neurotoxicity and ameliorate impaired recognition. Among the various strategies for AD treatment, phototherapy, including photothermal therapy (PTT), photodynamic therapy (PDT), and photoresponsive release systems have attracted increased attention because of the spatiotemporal controllability. Under the irradiation of light, the heat or reactive oxygen species generated by photothermal or photodynamic processes significantly enhances the efficacy of the inhibitor or modulator, and the "caged" drug can be accurately released at the intended site, thus avoiding adverse effects. This review, from a viewpoint of materials, focuses on the recent advances in modulating Aβ aggregation by light that irradiates on the materials that function on modulating Aβ aggregation. Representative examples of PTT, PDT, and photoresponsive drug release systems are discussed in terms of inhibitory mechanism, the unique properties of materials, and the design of modulators. The major challenges of phototherapy against AD are addressed and the promising prospects are proposed. It is concluded that the noninvasive light-assisted approaches will become a promising strategy for intensifying the modulation of Aβ aggregation and thus facilitating AD treatment. STATEMENT OF SIGNIFICANCE: Alzheimer's disease (AD) with the hallmark of amyloid-β protein (Aβ) deposition is affecting more than 50 million people globally. It is urgent to explore intelligent materials to modulate Aβ aggregation. This review summarizes the intensified modulation of Aβ aggregation by a variety of photoresponsive materials including photothermal, photosensitizing and photoresponsive release materials, focusing on their characteristics and functionalities. We believe this review would arouse more interest in the research field of stimuli-responsive materials and promote their clinical applications in AD therapy.