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

Design and preparation of naringenin loaded functional biomimetic nano-drug delivery system for Alzheimer's disease

Efficient brain drug delivery has been a challenge in the treatment of Alzheimer's Disease and other brain disorders as blood-brain barrier (BBB) impedes most drugs to reach brain. To overcome this obstacle, we developed a novel TGN decorated erythrocyte membrane-coated poly (lactic-co-glycolic acid) nanoparticle (TRNNs). The nanoparticle significantly boosted the penetration (7.3 times) in a U-118MG and HCMEC/D3 cell co-culture BBB model in vitro. Living image was performed to assess the TRNNs distribution in vivo. The fluorescence intensity in the isolated brain of TRDNs-treated mice was about 8 times that of the DNs-treated. In the novel object recognition test, the mice after administration of TRDNs showed higher recognition index (0.414 ± 0.016) than the model group (0.275 ± 0.019). A significant increase in the number of dendritic spines from TRNNs administrated mice hippocampi neurons was observed after Golgi stain. This improvement of neurons was also confirmed by the significant high expression of PSD95 protein level in hippocampi. We measured the OD values of Aβ25-35 induced PC12 cells that pre-treatment with different nanoparticles and concluded that TRNNs had a robust neuroprotection effect. Above all, functional biomimetic nanoparticles could increase the accumulation of naringenin into brain, thereby enable the drug to exert greater therapeutic effects.

The dual role of photodynamic therapy to treat cancer and microbial infection

Photodynamic therapy (PDT) is a minimally invasive treatment showing promise against cancer and microbial infections. PDT targets tumor cells while sparing healthy tissue, reducing side effects. It induces immunogenic cell death, potentially stimulating antitumor immune responses and reducing cancer recurrence. In microbial treatment, PDT effectively combats bacteria, fungi and viruses. Combining PDT with chemotherapy, radiotherapy and immunotherapy enhances its efficacy. However, challenges such as tumor hypoxia, limited tissue penetration and phototoxicity necessitate ongoing research efforts to optimize PDT protocols and overcome limitations. Overall, PDT is versatile and continually advancing with refined protocols to improve its clinical utility against cancer and microbial infections.

Rationally Designed Peptoid Inhibitors of Amyloid-β Oligomerization

While plaques comprised of fibrillar Aβ aggregates are hallmarks of Alzheimer's disease, soluble Aβ oligomers present higher neurotoxicity. Thus, one therapeutic approach is to prevent the formation of Aβ oligomers and reduce their associated harmful effects. We have proposed a peptoid mimic of the Aβ hydrophobic KLVFF core as an ideal candidate aggregation inhibitor due to its ability to evade proteolytic degradation via repositioning of the side chain from the α-carbon to the amide nitrogen. This peptoid, JPT1, utilizes chiral sidechains to achieve a helical structure, while C-terminal addition of two phenylalanine residues places aromatic groups on two sides of the helix with spacing designed to facilitate interaction with amyloid β-sheet structure. We have previously shown that JPT1 modulates Aβ fibril formation. Here, we demonstrate that JPT1 also modulates Aβ oligomerization, and we explore the role of the charge on the linker between the KLVFF mimic and the extended aromatic residues. Additionally, we demonstrate that peptoid-induced changes in Aβ oligomerization correlate with attenuation of oligomer-induced nuclear factor-κB activation in SH-SY5Y human neuroblastoma cells. These findings support the therapeutic potential of peptoids to target early stages of Aβ aggregation and impact the associated Aβ-induced cellular response.

CeO2 In Situ Growth on Red Blood Cell Membranes: CQD Coating and Multipathway Alzheimer's Disease Therapy under NIR

Alzheimer's disease (AD) has a complex etiology and diverse pathological processes. The therapeutic effect of single-target drugs is limited, so simultaneous intervention of multiple targets is gradually becoming a new research trend. Critical stages in AD progression involve amyloid-β (Aβ) self-aggregation, metal-ion-triggered fibril formation, and elevated reactive oxygen species (ROS). Herein, red blood cell membranes (RBC) are used as templates for the in situ growth of cerium oxide (CeO2) nanocrystals. Then, carbon quantum dots (CQDs) are encapsulated to form nanocomposites (CQD-Ce-RBC). This strategy is combined with photothermal therapy (PTT) for AD therapy. The application of RBC enhances the materials' biocompatibility and improves immune evasion. RBC-grown CeO2, the first application in the field of AD, demonstrates outstanding antioxidant properties. CQD acts as a chelating agent for copper ions, which prevents the aggregation of Aβ. In addition, the thermal effect induced by near-infrared laser-induced CQD can break down Aβ fibers and improve the permeability of the blood-brain barrier. In vivo experiments on APP/PS1 mice demonstrate that CQD-Ce-RBC combined with PTT effectively clears cerebral amyloid deposits and significantly enhances learning and cognitive abilities, thereby retarding disease progression. This innovative multipathway approach under light-induced conditions holds promise for AD treatment.

Nanomaterials-based advanced systems for photothermal / photodynamic therapy of oral cancer

The traditional clinical approaches for oral cancer consist of surgery, chemotherapy, radiotherapy, immunotherapy, and so on. However, these treatments often induce side effects and exhibit limited efficacy. Photothermal therapy (PTT) emerges as a promising adjuvant treatment, utilizing photothermal agents (PTAs) to convert light energy into heat for tumor ablation. Another innovative approach, photodynamic therapy (PDT), leverages photosensitizers (PSs) and specific wavelength laser irradiation to generate reactive oxygen species (ROS), offering an effective and non-toxic alternative. The relevant combination therapies have been reported in the field of oral cancer. Simultaneously, the advancement of nanomaterials has propelled the clinical application of PTT and PDT. Therefore, a comprehensive understanding of PTT and PDT is required for better application in oral cancer treatment. Here, we review the use of PTT and PDT in oral cancer, including noble metal materials (e.g., Au nanoparticles), carbon materials (e.g., graphene oxide), organic dye molecules (e.g., indocyanine green), organic molecule-based agents (e.g., porphyrin-analog phthalocyanine) and other inorganic materials (e.g., MXenes), exemplify the advantages and disadvantages of common PTAs and PSs, and summarize the combination therapies of PTT with PDT, PTT/PDT with chemotherapy, PTT with radiotherapy, PTT/PDT with immunotherapy, and PTT/PDT with gene therapy in the treatment of oral cancer. The challenges related to the PTT/PDT combination therapy and potential solutions are also discussed.

Amyloid detection in neurodegenerative diseases using MOFs

Neurodegenerative diseases (amyloid diseases such as Alzheimer's and Parkinson's), stemming from protein misfolding and aggregation, encompass a spectrum of disorders with severe systemic implications. Timely detection is pivotal in managing these diseases owing to their significant impact on organ function and high mortality rates. The diverse array of amyloid disorders, spanning localized and systemic manifestations, underscores the complexity of these conditions and highlights the need for advanced detection methods. Traditional approaches have focused on identifying biomarkers using imaging techniques (PET and MRI) or invasive procedures. However, recent efforts have focused on the use of metal-organic frameworks (MOFs), a versatile class of materials known for their unique properties, in revolutionizing amyloid disease detection. The high porosity, customizable structures, and biocompatibility of MOFs enable their integration with biomolecules, laying the groundwork for highly sensitive and specific biosensors. These sensors have been employed using electrochemical and photophysical techniques that target amyloid species under neurodegenerative conditions. The adaptability of MOFs allows for the precise detection and quantification of amyloid proteins, offering potential advancements in early diagnosis and disease management. This review article delves into how MOFs contribute to detecting amyloid diseases by categorizing their uses based on different sensing methods, such as electrochemical (EC), electrochemiluminescence (ECL), fluorescence, Förster resonance energy transfer (FRET), up-conversion luminescence resonance energy transfer (ULRET), and photoelectrochemical (PEC) sensing. The drawbacks of MOF biosensors and the challenges encountered in the field are also briefly explored from our perspective.

Tau- and α-synuclein-targeted gold nanoparticles: applications, opportunities, and future outlooks in the diagnosis and therapy of neurodegenerative diseases

The use of nanomaterials in medicine offers multiple opportunities to address neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These diseases are a significant burden for society and the health system, affecting millions of people worldwide without sensitive and selective diagnostic methodologies or effective treatments to stop their progression. In this sense, the use of gold nanoparticles is a promising tool due to their unique properties at the nanometric level. They can be functionalized with specific molecules to selectively target pathological proteins such as Tau and α-synuclein for Alzheimer's and Parkinson's disease, respectively. Additionally, these proteins are used as diagnostic biomarkers, wherein gold nanoparticles play a key role in enhancing their signal, even at the low concentrations present in biological samples such as blood or cerebrospinal fluid, thus enabling an early and accurate diagnosis. On the other hand, gold nanoparticles act as drug delivery platforms, bringing therapeutic agents directly into the brain, improving treatment efficiency and precision, and reducing side effects in healthy tissues. However, despite the exciting potential of gold nanoparticles, it is crucial to address the challenges and issues associated with their use in the medical field before they can be widely applied in clinical settings. It is critical to ensure the safety and biocompatibility of these nanomaterials in the context of the central nervous system. Therefore, rigorous preclinical and clinical studies are needed to assess the efficacy and feasibility of these strategies in patients. Since there is scarce and sometimes contradictory literature about their use in this context, the main aim of this review is to discuss and analyze the current state-of-the-art of gold nanoparticles in relation to delivery, diagnosis, and therapy for Alzheimer's and Parkinson's disease, as well as recent research about their use in preclinical, clinical, and emerging research areas.

Advances in Antioxidant Nanomedicines for Imaging and Therapy of Alzheimer's Disease

Significance: Reactive oxygen species (ROS) are crucial signaling molecules in the regulation of numerous physiological activities including the formation and function of the central nervous system (CNS). So far, many functional antioxidant nanomedicines with ROS scavenging capability to reduce oxidative stress in Alzheimer's disease (AD) have been developed for both imaging and therapy of AD. Recent Advances: This review focuses on the most recent advances in antioxidant nanomedicines such as ROS-scavenging nanoparticles (NPs), NPs with intrinsic antioxidant activity, and drug-loaded antioxidant NPs for AD theranostics. In addition to antioxidant nanomedicines, the emerging phototherapy treatment paradigms and the promising preclinic drug carriers, such as exosomes and liposomes, are also introduced. Critical Issues: In general, excessive generation of ROS can cause lipid peroxidation, oxidative DNA, as well as protein damage, aggravating pathogenic alterations, accumulation of amyloid-beta plaques and neurofibrillary tangles in the brain. These negative factors further cause cell death, which is the beginning of AD. Future Directions: We anticipate that this review will help researchers in the area of preclinical research and clinical translation of antioxidant nanomedicines for AD imaging and therapy.

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.

Near-infrared II theranostic agents for the diagnosis and treatment of Alzheimer's disease

BACKGROUND

Near-infrared II theranostic agents have gained great momentum in the research field of AD owing to the appealing advantages. Recently, an array of activatable NIR-II fluorescence probes has been developed to specifically monitor pathological targets of AD. Furthermore, various NIR-II-mediated nanomaterials with desirable photothermal and photodynamic properties have demonstrated favorable outcomes in the management of AD.

METHODS

We summerized amounts of references and focused on small-molecule probes, nanomaterials, photothermal therapy, and photodynamic therapy based on NIR-II fluorescent imaging for the diagnosis and treatment in AD. In addition, design strategies for NIR-II-triggered theranostics targeting AD are presented, and some prospects are also addressed.

RESULTS

NIR-II theranostic agents including small molecular probes and nanoparticles have received the increasing attention for biomedical applications. Meanwhile, most of the theranostic agents exhibited the promising results in animal studies. To our surprise, the multifunctional nanoplatforms also show a great potential in the diagnosis and treatment of AD.

CONCLUSIONS

Although NIR-II theranostic agents showed the great potential in diagnosis and treatment of AD, there are still many challenges: 1) Faborable NIR-II fluorohpores are still lacking; 2) Biocompatibility, bioseurity and dosage of NIR-II theranostic agents should be further revealed; 3) New equipment and software associated with NIR-II imaging system should be explored.

Rofecoxib derivatives as NIR fluorescent probes for mitochondrial viscosity and in vivo imaging of Aβ plaques

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder for which the underlying causes remain largely unknown. Therefore, the development of imaging agents capable of detecting biomarkers associated with this disease is crucial. Dual-functional probes are particularly important as they can track two biomarkers at the same time and examine their interaction. Herein, Two red-emissive dual-functional fluorescent probes, RC-1 and RA-2, have been designed and synthesized based on the Rofecoxib scaffold. When probes (RC-1 and RA-2) are in viscous media or bound to Aβ aggregates, there is a dramatic enhancement in fluorescence emission due to the constraint of the twisted intramolecular charge transfer effect (TICT). RC-1 with ideal blood-brain barrier (BBB) penetrability enables visualization of Aβ plaques in vivo AD mice. These results suggest that RC-1 and RA-2 have the potential to serve as powerful fluorescence imaging agents for Aβ and mitochondria-related pathology in AD.

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.

Biocompatible zeolite-dye composites with anti-amyloidogenic properties

One of the most attractive approaches in biomedicine and pharmacy is the application of multifunctional materials. The mesoporous structure of clinoptilolite (CZ) absorbs various types of substances and can be used as a model for studying the carriers for targeted drug delivery with controlled release. CZ-dye composites are fabricated by incorporation into clinoptilolite pores commonly used dyes, aluminum phthalocyanine, zinc porphine, and hypericin. We examined and compared the effect of pure dyes and CZ-dye composites on insulin amyloidogenesis. The formation of insulin amyloid fibrils and the disassembly of preformed fibrils is significantly affected by any of the three compounds, however, the strongest effect is observed for aluminum phthalocyanine indicating a structurally-dependent anti-amyloidogenic activity of the dyes. The incorporation of dyes into CZ particles resulted in enhanced anti-amyloidogenic activity in comparison to pure CZ particles. The cell metabolic activity, biocompatibility and fluorescence biodistribution of the dyes entrapped in the composites were tested in vitro (U87 MG cells) and in vivo in the quail chorioallantoic membrane model. Considering the photoactive properties of the dyes used, we assume their applicability in photodiagnostics and photodynamic therapy. It can also be expected that their anti-amyloidogenic potential can be enhanced by photodynamic effect.

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.

Effect of plasmonic excitation on mature insulin amyloid fibrils

Interactions between amyloid protein structures and nanomaterials have been extensively studied to develop effective inhibitors of amyloid aggregation. Limited investigations are reported on the impact of nanoparticles on mature fibrils. In this work, gold nanoparticles are used as photothermal agents to alter insulin fibrils. To this end, gold colloids bearing a negatively charged capping shell, with an average diameter of 14 nm and a plasmon resonance maximum at 520 nm are synthesized. The effects on mature insulin fibril morphology and structure upon plasmonic excitation of the nanoparticles-fibril samples have been monitored by spectroscopic and microscopic methods. The obtained data indicate that an effective destruction of the amyloid aggregates occur upon irradiation of the plasmonic nanoparticles, allowing the development of emerging strategies to alter the structure of amyloid fibrils.

The Beneficial Role of Photobiomodulation in Neurodegenerative Diseases

Photobiomodulation (PBM), also known as Low-level Laser Therapy (LLLT), involves the use of light from a laser or light-emitting diode (LED) in the treatment of various disorders and it has recently gained increasing interest. Progressive neuronal loss with attendant consequences such as cognitive and/or motor decline characterize neurodegenerative diseases. The available therapeutic drugs have only been able to provide symptomatic relief and may also present with some side effects, thus precluding their use in treatment. Recently, there has been an exponential increase in interest and attention in the use of PBM as a therapy in various neurodegenerative diseases in animal studies. Because of the financial and social burden of neurodegenerative diseases on the sufferers and the need for the discovery of potential therapeutic inventions in their management, it is pertinent to examine the beneficial effects of PBM and the various cellular mechanisms by which it modulates neural activity. Here, we highlight the various ways by which PBM may possess beneficial effects on neural activity and has been reported in various neurodegenerative conditions (Alzheimer's disease, Parkinson's disease, epilepsy, TBI, stroke) with the hope that it may serve as an alternative therapy in the management of neurodegenerative diseases because of the biological side effects associated with drugs currently used in the treatment of neurodegenerative diseases.

Molecular Cage with Dual Outputs of Photochromism and Luminescence Both in Solution and the Solid State

The rational design of stimuli-responsive materials requires a deep understanding of the structure-activity relationship. Herein, we proposed an intramolecular conformation-locking strategy─incorporating flexible tetraphenylethylene (TPE) luminogens into the rigid scaffold of a molecular cage─to produce a molecular photoswitch with dual outputs of luminescence and photochromism in solution and in the solid states at once. The molecular cage scaffold, which restricts the intramolecular rotations of the TPE moiety, not only helps to preserve the luminescence of TPE in a dilute solution but facilitates the reversible photochromism on account of the intramolecular cyclization/cycloreversion reactions. Furthermore, we demonstrate assorted applications of this multiresponsive molecular cage, e.g., photo-switchable patterning, anticounterfeiting, and selective vapochromism sensing.

Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies

Cognitive function is an important ability of the brain, but cognitive dysfunction can easily develop once the brain is injured in various neuropathological conditions or diseases. Photobiomodulation therapy is a type of noninvasive physical therapy that is gradually emerging in the field of neuroscience. Transcranial photobiomodulation has been commonly used to regulate neural activity in the superficial cortex. To stimulate deeper brain activity, advanced photobiomodulation techniques in conjunction with photosensitive nanoparticles have been developed. This review addresses the mechanisms of photobiomodulation on neurons and neural networks and discusses the advantages, disadvantages and potential applications of photobiomodulation alone or in combination with photosensitive nanoparticles. Photobiomodulation and its associated strategies may provide new breakthrough treatments for cognitive improvement.

NIR-excited upconversion nanoparticles used for targeted inhibition of Aβ42 monomers and disassembly of Aβ42 fibrils

Much attention has been paid to oxidising amyloid-β peptides (Aβ) for inhibiting their aggregation using photosensitive materials. However, the low penetration of ultraviolet/visible light into biological tissues and low targeting properties of the materials hinder their application. Here, we constructed a novel platform for attenuating the neurotoxicity of Aβ through functional upconversion nanoparticles (UCNPs@SiO₂-ThS). UCNPs@SiO₂-ThS can not only inhibit the aggregation of Aβ₄₂ monomers, but also disassemble Aβ₄₂ fibrils by its selective photooxidative capacity under the irradiation of near-infrared (NIR) light. Moreover, based on the enhancement of ThS fluorescence after attaching to Aβ₄₂ fibrils, only Aβ₄₂ fibrils exposed to both UCNPs@SiO₂-ThS and light can be oxidized rather than other normal proteins. To further enhance Aβ-target photooxygenation, we introduced the Aβ-target peptide (KLVFF) on the surface. Compared to traditional chemotherapies and radiotherapies, this novel PDT strategy shows remarkably reduced side effects and improved targeting.

Photobiomodulation for Alzheimer's disease: photoelectric coupling effect on attenuating Aβ neurotoxicity

Alzheimer's disease (AD) and dementia are the most worrying health problems faced by people globally today. Although the pathological features of AD consisting of amyloid-beta (Aβ) plaques in the extracellular space (ECS) and intracellular tau tangles are well established, the developed medicines targeting these two proteins have not obtained the expected clinical effects. Photobiomodulation (PBM) describes the therapeutic use of red light (RL) or near-infrared light (NIR) to serve as a noninvasive neuroprotective strategy for brain diseases. The present review discusses the mechanisms of the photoelectric coupling effect (light energy-induced special electronic transition-related alterations in protein structure) of PBM on reducing Aβ toxicity. On the one hand, RL or NIR can directly disassemble Aβ in vitro and in vivo. On the other hand, formaldehyde (FA)-inhibited catalase (CAT) and H2O2-inactived formaldehyde dehydrogenase (FDH) are formed a vicious circle in AD; however, light energy not only activates FDH to degrade excessive FA (which crosslinks Aβ monomer to form Aβ oligomers and senile plaques) but also sensitizes CAT to reduce hydrogen peroxide levels (H2O2, which can facilitate Aβ aggregation and enhance FA generation). In addition, it also activates mitochondrial cytochrome-c to produce ATP in the neurons. Clinical trials of phototherapeutics or oral coenzyme Q10 have shown positive effects in AD patients. Hence, a promising strategy combined PBM with nanopacked Q10 has been proposed to apply for treating AD.

Photoresponsive polymeric microneedles: An innovative way to monitor and treat diseases

Microneedles (MN) technology is an emerging technology for the transdermal delivery of therapeutics. When combined with photoresponsive (PR) materials, MNs can deliver therapeutics precisely and effectively with enhanced efficacy or synergistic effects. This review systematically summarizes the therapeutic applications of PRMNs in cancer therapy, wound healing, diabetes treatment, and diagnostics. Different PR approaches to activate and control the release of therapeutic agents from MNs are also discussed. Overall, PRMNs are a powerful tool for stimuli-responsive controlled-release therapeutic delivery to treat various diseases.

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.

Soft nano and microstructures for the photomodulation of cellular signaling and behavior

Photoresponsive soft materials are everywhere in the nature, from human's retina tissues to plants, and have been the inspiration for engineers in the development of modern biomedical materials. Light as an external stimulus is particularly attractive because it is relatively cheap, noninvasive to superficial biological tissues, can be delivered contactless and offers high spatiotemporal control. In the biomedical field, soft materials that respond to long wavelength or that incorporate a photon upconversion mechanism are desired to overcome the limited UV-visible light penetration into biological tissues. Upon light exposure, photosensitive soft materials respond through mechanisms of isomerization, crosslinking or cleavage, hyperthermia, photoreactions, electrical current generation, among others. In this review, we discuss the most recent applications of photosensitive soft materials in the modulation of cellular behavior, for tissue engineering and regenerative medicine, in drug delivery and for phototherapies.

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.

Germanene-modified chitosan hydrogel for treating bacterial wound infection: An ingenious hydrogel-assisted photothermal therapy strategy

The elaborate design of an ingenious hydrogel-assisted photothermal therapy (PTT) platform is a promising strategy for treating bacterial wound infections. Herein, a new generation of germanene nanocrystals (Ge NCs) with excellent photothermal performance are prepared via an ice-bath sonication liquid-phase exfoliation technique. Whereafter, by crosslinking interaction between chitosan and zinc acetate, as well as self-assembly property between Ge NCs and chitosan, we successfully construct an innovative germanene-modified chitosan antimicrobial hydrogel (CS/Ge NCs^0.8) integrating capture and killing bacteria performances. When co-cultured with bacteria, CS/Ge NCs^0.8 hydrogel with the positive charge can adsorb and restrict bacteria in the range of PTT destruction. Once the near-infrared laser is introduced, CS/Ge NCs^0.8 hydrogel will effectively convert light energy into localized heat, further inducing bacterial death. By this entirely novel modality, CS/Ge NCs^0.8 hydrogel exhibits marvelous antibacterial property against E. coli and S. aureus in vitro. Furthermore, in vivo studies demonstrate that CS/Ge NCs^0.8 hydrogel possesses the ability to significantly rescue S. aureus-induced skin wound infections, suggesting CS/Ge NCs^0.8 hydrogel can be served as an antibacterial dressing. Strikingly, this is the first-ever report of CS/Ge NCs^0.8 hydrogel in the antibacterial field, which may spur a wave of developing Ge-based biomaterials to benefit biomedical applications.

Nontoxic silicene photothermal agents with high near-infrared absorption for disassembly of Alzheimer's amyloid‑β fibrils

The disassembly and eliminating the amyloid-β (Aβ) aggregates has become an effective way to treat Alzheimer's disease (AD). Herein, for the first time, the near-infrared (NIR) activated silicene nanosheets (SNSs) have been identified as an effective nontoxic photothermal conversion agent for irreversibly disassembly of the Aβ_33-42 aggregates. The SNSs synthesized by a combination of mild oxidation method and liquid exfoliation method possess good biocompatibility and biodegradability, and high near-infrared photothermal conversion capabilities. Under NIR light, the SNSs could disassemble the large and dense Aβ_33-42 mature fibrils into short fibrils and even form thin films, leading to the degradation rate of 96.47%. The circular dichroism spectrum, fluorescent spectra, and nanostructure were analyzed to monitor the photothermal degradation of mature Aβ_33-42 fibrils for elaborating the mechanism beneath. This study might provide a clue for developing potential therapeutic strategy for AD and related neurodegenerative diseases.

Dual-action nanoplatform with a synergetic strategy to promote oxygen accumulation for enhanced photodynamic therapy against hypoxic tumors

With the development of redox-related therapy modalities in cancer therapy, photodynamic therapy (PDT) has gradually become the most widely used type in the clinic. However, the hypoxic tumor microenvironment restricted the curative effect of PDT. Here, a strategic hypoxia relief nanodrug delivery system (SHRN) with a synergetic strategy was designed to alleviate tumor hypoxia on the basis of PDT. Specifically, the oxygen producer MnO₂, oxygen consumption inhibitor atovaquone (ATO) and photosensitizer hypericin (HY) were loaded in SHRN. MnO₂ reacted with excess H₂O₂ in the tumor microenvironment to increase oxygen generation, while ATO inhibited electron transfer in the aerobic respiratory chain to decrease oxygen consumption. Then, HY utilized this sufficient oxygen to produce ROS under irradiation to enhance the PDT effect. In vitro and in vivo assays confirmed that SHRN exhibits powerful and overall antitumor PDT effects. This formulation may provide an alternative strategy for the development of PDT effects in hypoxic tumor microenvironments. STATEMENT OF SIGNIFICANCE: We constructed a strategic hypoxia relief nanodrug delivery system (SHRN) with a synergetic strategy to alleviate tumor hypoxia on the basis of photodynamic therapy (PDT). This work uniquely aimed at not only increased O₂ generation in hypoxic tumor microenvironment but also reduced O₂ consumption. Moreover, we designed a nanodrug delivery system to enhance the tumor permeability of SHRN. In vitro and in vivo assays all confirmed that SHRN exhibited powerful and overall antitumor effects. This formulation may provide an alternative strategy for the development of the PDT effect in hypoxic solid tumor.

Composite of gold nanoclusters and basified human serum albumin significantly boosts the inhibition of Alzheimer's β-amyloid by photo-oxygenation

Photo-oxygenation has become an effective way to inhibit Alzheimer's β-amyloid protein (Aβ) fibrillogenesis, which involves oxidative modification of Aβ by photo-oxidants. However, limitations of the current photo-oxidants, such as low biocompatibility and low affinity for Aβ, hinder the progression of the photo-oxygenation strategy. Herein, using human serum albumins (HSA) with binding affinity for Aβ as a platform, we have fabricated HSA-stabilized gold nanoclusters (AuNCs@HSA) and further modified the AuNCs@HSA with ethylenediamine to create basified HSA (HSA-B)-stabilized AuNCs. The basified composite, AuNCs@HSA-B, showed significantly higher potency on the inhibition of β-amyloid formation and capability of reactive oxidative species generation than AuNCs@HSA. In addition to the inhibition effect, under near-infrared (NIR) laser irradiation, AuNCs@HSA-B generated singlet oxygen to oxygenate Aβ monomers, distinctly alleviating Aβ-mediated neurotoxicity at a low concentration. In vivo studies demonstrated that NIR-activated AuNCs@HSA-B promoted the lifespan extension of transgenic C. elegans strain CL2006 by decreasing the Aβ burden. This well-designed AuNCs@HSA-B integrates inhibition, Aβ targeting, and photo-oxygenation, providing new insights into the development of protein-based photo-oxidant against Alzheimer's β-amyloid. STATEMENT OF SIGNIFICANCE: Alzheimer's disease (AD) has been threatening human health for more than 100 years. Recently, researchers have focused on inhibiting β-amyloid protein (Aβ) aggregation by exploring photo-excited biomaterials, which enable modulation of Aβ fibrillization with high spatiotemporal controllability. The present work demonstrates the fabrication of basified human serum albumins (HSA-B)-stabilized gold nanoclusters (AuNCs@HSA-B), and shows the potential of this near-infrared (NIR) laser-activated AuNCs@HSA-B as a photo-oxidant against Aβ aggregation by photo-oxygenation. Our work should open a new horizon in the design of protein-based photo-oxidant for treating AD in the future.

Near-infrared Irradiation Controlled Thermo-Switchable Polymeric Photosensitizer against β-Amyloid Fibrillation

Photothermal therapy (PTT) as an emerging paradigm toward degradation of amyloid-β (Aβ) aggregations has become an effective way of treating Alzheimer’s disease (AD). A promising PTT therapeutic option requires control...

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.