Photoinduced elimination of senescent microglia cells in vivo by chiral gold nanoparticles

Current strategies for senescence treatment: Focused on theranostic performance of nanomaterials

Age-related diseases imposed heavy burdens to the healthcare systems globally, while cell senescence served as one fundamental molecular/cellular basis for these diseases. How to tackle the senescence-relevant problems is a hotspot for biomedical research. In this review article, the hallmarks and molecular pathways of cell senescence were firstly discussed, followed by the introduction of the current anti-senescence strategies, including senolytics and senomorphics. With suitable physical or chemical properties, multiple types of nanomaterials were used successfully in senescence therapeutics, as well as senescence detection. Based on the accumulating knowledges for senescence, the rules of how to use these nanoplatforms more efficiently against senescence were also summarized, including but not limited to surface modification, material-cargo interactions, factor responsiveness etc. The comparison of these "senescence-selective" nanoplatforms to other treatment options (prodrugs, ADCs, PROTACs, CART etc.) was also given. Learning from the past, nanotechnology can add more choice for treating age-related diseases, and provide more (diagnostic) information to further our understanding of senescence process.

Chiral Gold Nanostructure Monolayers as SERS Substrates for Ultrasensitive Detection of Enantiomer Biomarkers of Alzheimer's Disease

The early diagnosis of neurodegenerative diseases, such as Alzheimer's disease (AD), requires the identification of sensitive and specific biomarkers. Detecting chiral molecules at concentrations relevant to disease states remains challenging. Herein, a new type of chiral gold nanostructure induced by D-/L-cysteine-leucine dipeptides with a g-factor of 0.1 was successfully synthesized for enantiomer biomarker detection. To enhance the discrimination performance, the chiral gold nanostructures were assembled into D-/L-Au monolayers. As surface-enhanced Raman scattering (SERS) substrates, the D-/L-Au monolayers simultaneously deliver molecular structural specificity and enantioselectivity within a single spectrum, which can be a versatile, label-free chiral discrimination strategy for the detection of D-/L-kynurenine (Kyn). The mechanism was unveiled to involve high enantioselective adsorption energies between L- and D-Kyn on the lattice plane (221), resulting in enantioselective sensing. The results showed that the L-Au monolayer reached a limit of detection (LOD) of 3.7 nm for L-Kyn, while the D-Au monolayer reached an LOD of 3.6 nM for D-Kyn. Notably, there was a significant difference in D-Kyn levels between AD patients and healthy individuals in serum samples, a distinction not observed for L-Kyn, which positioned D-Kyn as a potential novel biomarker for clinical prediagnosis of AD patients, marking the first report of its kind worldwide. This study provides a robust tool for advancing biomedical science and clinical diagnostics.

DON-Loaded Nanodrug-T Cell Conjugates With PD-L1 Blockade for Solid Tumor Therapy

Adoptive T-cell therapy (ACT) holds significant promise for treating solid tumors but is often constrained by insufficient T-cell infiltration, survival, and functional persistence. To overcome these obstacles, we developed DON-loaded nanodrug-T cell conjugates with PD-L1 blockade, forging a dynamic mutualistic relationship between T cells and therapeutic agents. Sustained release of glutamine antagonist 6-diazo-5-oxo-L-norleucine (DON) within these conjugates continuously enhances T-cell endurance and potency by promoting memory differentiation and elevating crucial adhesion and motility genes. Concurrently, PD-L1 blocking peptides liberate T cells from immunosuppression, assisting T cells with precision toward tumor sites. This dual-targeting strategy-T cells directed at tumor antigens and peptides at PD-L1- enriches the tumor microenvironment with potent therapeutics, amplifying T cell-driven tumor destruction. Our approach effectively overcomes the critical barriers of ACT-infiltration, persistence, and efficacy-unlocking the full therapeutic potential of T-cell therapy against complex solid tumors.

Enantioselective synthesis of chiroplasmonic helicoidal nanoparticles by nanoconfinement in chiral dielectric shells

Helicoid metal nanoparticles with intrinsic chirality have unveiled tailorable properties and unlocked many chirality-related applications across various fields. Nevertheless, the existing strategies for enantioselective synthesis of helicoid metal nanoparticles have been predominantly limited to gold. Here, we demonstrate a robust and versatile strategy for the enantioselective synthesis of helicoid nanoparticles beyond gold, leveraging chiral nanoconfinement provided by chiral SiO2 or nanoshells. The chiral nanoconfinement strategy enables the decoupling of ligand-directed crystal growth from chiral induction, allowing for the independent tuning of these two critical aspects. As a result, this approach can not only facilitate the replication of chiral shapes from the chiral nanoshells but also allow the generation of alternative chiral shapes. By employing this approach, we demonstrate the enantioselective synthesis of helicoid Pt, Au@Pt, Au@Pd, Au@Ag, and Au@Cu nanoparticles. The chiroplasmonic properties of Pt- and Pd-based chiral nanoparticles have been discovered, and the inversion of chiroplasmonic properties of Ag-based chiral nanoparticles via facet control has been documented and theoretically explained. The chiral nanoconfinement strategy enriches the toolbox for creating chiral nanoparticles and supports their exploration in diverse applications.

Chiral Inorganic Nanomaterial-Based Diagnosis and Treatments for Neurodegenerative Diseases

Chiral nanomaterials are widely investigated over recent decades due to their biocompatibility and unique chiral effects. These key properties have significantly promoted the rapid development of chiral nanomaterials in bioengineering and medicine. In this review, the basic principles of constructing chiral nanomaterials along with the latest progress in research are comprehensively summarized. Then, the application of chiral nanomaterials for the diagnosis of neurodegenerative diseases (NDDs) is systematically described. In addition, the significant potential and broad prospects of chiral nanomaterials in the treatment of NDDs are highlighted from several aspects, including the disaggregation of neurofibrils, the scavenging of reactive oxygen species, regulation of the microbial-gut-brain axis, the elimination of senescent cells, and the promotion of directed differentiation in neural stem cells. Finally, a perspective of the challenges and future development of chiral nanomaterials for the treatment of NDDs is provided.

Recent Advances in Chiral Gold Nanomaterials: From Synthesis to Applications

In recent years, the field of chiral gold nanomaterials has witnessed significant advancements driven by their unique properties and diverse applications in various scientific domains. This review provides an in-depth examination of the synthesis methodologies and evolving applications of chiral gold nanomaterials, which have emerged as vital tools in areas such as antibacterial therapies, biosensing, catalysis, and nanomedicine. We start by discussing various synthesis techniques, focused on seed-mediated growth and circularly polarized light-assisted methods, each contributing to the controlled synthesis of chiral gold nanostructures with tailored optical activities. This review further delves into the applications of these nanomaterials, showcasing their potential in combating antibiotic-resistant bacteria, improving cancer immunotherapy, promoting tissue regeneration, and enabling precise biosensing through enhanced sensitivity and selectivity. We highlight the fundamental principles of chirality and its critical role in biological systems, emphasizing the importance of chiral gold nanomaterials in enhancing optical signals and facilitating molecular interactions. By consolidating recent findings and methodologies, this review endeavors to illuminate the promising future of chiral gold nanomaterials and their critical role in addressing contemporary scientific challenges.

Nanodevice-Mediated Immune Cell Recruitment: Targeting Senescent Cells via MMP-3-Responsive CXCL12-Coated Nanoparticles

Senescent cells are involved in age-related disorders in different organs and are therapeutic targets for fibrotic and chronic pathologies. Immune-modulating agents, able to enhance senescent cell detection and elimination by endogenous immune cells, have emerged as pharmacological strategies. We report herein a nanoparticle for immune cell-mediated senolytic therapy designed to recruit immune cells in response to specific enzymatic matrix metalloproteinase-3 (MMP-3) activity in the senescence-associated secretory phenotype. For this, mesoporous silica nanoparticles (MSNs) are coated with a peptide substrate of the metalloproteinase MMP-3, and the peptide is decorated with chemokine CXCL12 that enhances immune cell recruitment (NPs@CXCL12). Controlled release studies confirmed the progressive and specific release of CXCL12 in the presence of MMP-3. The ability of immune cell recruitment in response to a senescent microenvironment (senescent WI-38 fibroblasts) is confirmed by Transwell migration assays with green fluorescent Jurkat T-cells, showing NPs@CXCL12 has an enhanced chemotaxis effect toward senescent cells compared to free CXCL12 (2-fold). Moreover, the cytotoxic capacity of human primary natural killer (NK) cells over senescent WI-38 is also confirmed, and their migration trajectories in response to NPs@CXCL12 or free CXCL12 are monitored by using a microfluidic device. Results confirm the ability of NPs@CXCL12 to generate a chemotactic gradient able to attract NK cells. When compared with free CXCL12, the NPs@CXCL12 system showed a reduction of up to 15.56% in the population of NK cells migrating toward free CXCL12 under competitive conditions. This study demonstrates the potential of designing nanoparticles to recruit immune cells under specific responses to eliminate senescent cells. Results confirm that NPs@CXCL12 can effectively establish a chemotactic gradient to attract NK cells.

Navitoclax safety, tolerability, and effect on biomarkers of senescence and neurodegeneration in aged nonhuman primates

Alzheimer's disease (AD) is the most common global dementia and is universally fatal. Most late-stage AD disease-modifying therapies are intravenous and target amyloid beta (Aβ), with only modest effects on disease progression: there remains a high unmet need for convenient, safe, and effective therapeutics. Senescent cells (SC) and the senescence-associated secretory phenotype (SASP) drive AD pathology and increase with AD severity. Preclinical senolytic studies have shown improvements in neuroinflammation, tau, Aβ, and CNS damage; most were conducted in transgenic rodent models with uncertain human translational relevance. In this study, aged cynomolgus monkeys had significant elevation of biomarkers of senescence, SASP, and neurological damage. Intermittent treatment with the senolytic navitoclax induced modest reversible thrombocytopenia; no serious drug-related toxicity was noted. Navitoclax reduced several senescence and SASP biomarkers, with CSF concentrations sufficient for senolysis. Finally, navitoclax reduced TSPO-PET frontal cortex binding and showed trends of improvement in CSF biomarkers of neuroinflammation, neuronal damage, and synaptic dysfunction. Overall, navitoclax administration was safe and well tolerated in aged monkeys, inducing trends of biomarker changes relevant to human neurodegenerative disease.

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.

An Indocyanine Green-Based Nanoprobe for In Vivo Detection of Cellular Senescence

There is an urgent need to improve conventional cancer-treatments by preventing detrimental side effects, cancer recurrence and metastases. Recent studies have shown that presence of senescent cells in tissues treated with chemo- or radiotherapy can be used to predict the effectiveness of cancer treatment. However, although the accumulation of senescent cells is one of the hallmarks of cancer, surprisingly little progress has been made in development of strategies for their detection in vivo. To address a lack of detection tools, we developed a biocompatible, injectable organic nanoprobe (NanoJagg), which is selectively taken up by senescent cells and accumulates in the lysosomes. The NanoJagg probe is obtained by self-assembly of indocyanine green (ICG) dimers using a scalable manufacturing process and characterized by a unique spectral signature suitable for both photoacoustic tomography (PAT) and fluorescence imaging. In vitro, ex vivo and in vivo studies all indicate that NanoJaggs are a clinically translatable probe for detection of senescence and their PAT signal makes them suitable for longitudinal monitoring of the senescence burden in solid tumors after chemotherapy or radiotherapy.

Chiral MoS2@BC fibrous membranes selectively promote peripheral nerve regeneration

BACKGROUND

Molybdenum disulfide (MoS2) has excellent physical and chemical properties. Further, chiral MoS2 (CMS) exhibits excellent chiroptical and enantioselective effects, and the enantioselective properties of CMS have been studied for the treatment of neurodegenerative diseases. Intriguingly, left- and right-handed materials have different effects on promoting the differentiation of neural stem cells into neurons. However, the effect of the enantioselectivity of chiral materials on peripheral nerve regeneration remains unclear.

METHODS

In this study, CMS@bacterial cellulose (BC) scaffolds were fabricated using a hydrothermal approach. The CMS@BC films synthesized with L-2-amino-3-phenyl-1-propanol was defined as L-CMS. The CMS@BC films synthesized with D-2-amino-3-phenyl-1-propanol was defined as D-CMS. The biocompatibility of CMS@BC scaffolds and their effect on Schwann cells (SCs) were validated by cellular experiments. In addition, these scaffolds were implanted in rat sciatic nerve defect sites for three months.

RESULTS

These chiral scaffolds displayed high hydrophilicity, good mechanical properties, and low cytotoxicity. Further, we found that the L-CMS scaffolds were superior to the D-CMS scaffolds in promoting SCs proliferation. After three months, the scaffolds showed good biocompatibility in vivo, and the nerve conducting velocities of the L-CMS and D-CMS scaffolds were 51.2 m/s and 26.8 m/s, respectively. The L-CMS scaffolds showed a better regenerative effect than the D-CMS scaffolds. Similarly, the sciatic nerve function index and effects on the motor and electrophysiological functions were higher for the L-CMS scaffolds than the D-CMS scaffolds. Finally, the axon diameter and myelin sheath thickness of the regenerated nerves were improved in the L-CMS group.

CONCLUSION

We found that the CMS@BC can promote peripheral nerve regeneration, and in general, the L-CMS group exhibited superior repair performance. Overall, the findings of this study reveal that CMS@BC can be used as a chiral nanomaterial nerve scaffold for peripheral nerve repair.

Neuroglia targeting nano-therapeutic approaches to rescue aging and neurodegenerating brain

Despite intense efforts at the bench, the development of successful brain-targeting therapeutics to relieve malicious neural diseases remains primitive. The brain, being a beautifully intricate organ, consists of heterogeneous arrays of neuronal and glial cells. Primarily acting as the support system for neuronal functioning and maturation, glial cells have been observed to be engaged more apparently in the progression and worsening of various neural pathologies. The diseased state is often related to metabolic alterations in glial cells, thereby modulating their physiological homeostasis in conjunction with neuronal dysfunction. A plethora of data indicates the effect of oxidative stress, protein aggregation, and DNA damage in neuroglia impairments. Still, a deeper insight is needed to gain a conflict-free understanding in this arena. As a consequence, glial cells hold the potential to be identified as promising targets for novel therapeutic approaches aimed at brain protection. In this review, we describe the recent strides taken in the direction of understanding the impact of oxidative stress, protein aggregation, and DNA damage on neuroglia impairment and neuroglia-directed nanotherapeutic approaches to mitigate the burden of various neural disorders.

An Antibody-directed and Immune Response Modifier-augmented Photothermal Therapy Strategy Relieves Aging via Rapid Immune Clearance of Senescent Cells

Cellular senescence is an irreversible and multifaceted process inducing tissue dysfunction and organismal aging, and thus the clearance of senescent cells can prevent or delay the onset of aging-related pathologies. Herein, we developed an augmented photothermal therapy strategy integrated with an antibody against β2-microglobulin (aB2MG) and an immune adjuvant imiquimod (R837) to effectively accelerate senescent cell apoptosis and clearance under a near-infrared light. With this strategy, the designed CroR@aB2MG enables the targeting of senescent cells and the application of photothermal therapy concomitantly, the initiation of immune clearance subsequently, and finally the realization of protective effects against senescence. Our results showed that the photo-induced heating effect caused senescent cells to quickly undergo apoptosis and the synchronous immune response accelerated the clearance of senescent cells in vitro and in vivo. Therefore, this photoactivated speedy clearing strategy may provide an efficient way for the treatment of senescence-related diseases by eliminating senescent cells with biomaterials.

Recent Advancement in Elimination Strategies and Potential Rejuvenation Targets of Senescence

Cellular senescence is a state of exiting the cell cycle, resisting apoptosis, and changing phenotype. Senescent cells (SCs) can be identified by large, distorted morphology and irreversible inability to replicate. In early development, senescence has beneficial roles like tissue patterning and wound healing, where SCs are cleared by the immune system. However, there is a steep rise in SC number as organisms age. The issue with SC accumulation stems from the loss of cellular function, alterations of the microenvironment, and secretions of pro-inflammatory molecules, consisting of cytokines, chemokines, matrix metalloproteinases (MMPs), interleukins, and extracellular matrix (ECM)-associated molecules. This secreted cocktail is referred to as the senescence-associated secretory phenotype (SASP), a hallmark of cellular senescence. The SASP promotes inflammation and displays a bystander effect where paracrine signaling turns proliferating cells into senescent states. To alleviate age-associated diseases, researchers have developed novel methods and techniques to selectively eliminate SCs in aged individuals. Although studies demonstrated that selectively killing SCs improves age-related disorders, there are drawbacks to SC removal. Considering favorable aspects of senescence in the body, this paper reviews recent advancements in elimination strategies and potential rejuvenation targets of senescence to bring researchers in the field up to date.

Relationship among α‑synuclein, aging and inflammation in Parkinson's disease (Review)

Parkinson's disease (PD) is a common neurodegenerative pathology whose major clinical symptoms are movement disorders. The main pathological characteristics of PD are the selective death of dopaminergic (DA) neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies containing α-synuclein (α-Syn) within these neurons. PD is associated with numerous risk factors, including environmental factors, genetic mutations and aging. In many cases, the complex interplay of numerous risk factors leads to the onset of PD. The mutated α-Syn gene, which expresses pathologicalα-Syn protein, can cause PD. Another important feature of PD is neuroinflammation, which is conducive to neuronal death. α-Syn is able to interact with certain cell types in the brain, including through phagocytosis and degradation of α-Syn by glial cells, activation of inflammatory pathways by α-Syn in glial cells, transmission of α-Syn between glial cells and neurons, and interactions between peripheral immune cells and α-Syn. In addition to the aforementioned risk factors, PD may also be associated with aging, as the prevalence of PD increases with advancing age. The aging process impairs the cellular clearance mechanism, which leads to chronic inflammation and the accumulation of intracellular α-Syn, which results in DA neuronal death. In the present review, the age-associated α-Syn pathogenicity and the interactions between α-Syn and certain types of cells within the brain are discussed to facilitate understanding of the mechanisms of PD pathogenesis, which may potentially provide insight for the future clinical treatment of PD.

Advances in Enantiomer-Dependent Nanotherapeutics

The nanoscale properties of nanomaterials, especially nanoparticles, including size, shape, and surface charge, have been extensively studied for their impact on nanomedicine. Given the inherent chiral nature of biological systems and their high enantiomeric selectivity, there is rising interest to manipulate the chirality of nanomaterials to enhance their biomolecular interactions and improve nanotherapeutics. Chiral nanostructures are currently more prevalently used in biosensing and diagnostic applications owing to their distinctive physical and optical properties, but they hold great promise for use in nanomedicine. In this Review, we first discuss stereospecific interactions between chiral nanomaterials and biomolecules before comparing the synthesis and characterization methods of chiral nanoparticles and nanoassemblies. Finally, we examine the applications of chiral nanotherapeutics in cancer, immunomodulation, and neurodegenerative diseases and propose plausible mechanisms in which chiral nanomaterials interact with cells for biological manipulation. This Review on chirality is a timely reminder of the arsenal of nanoscale modifications to boost research in nanotherapeutics.

Synthesis and Characterization of Gold Chiral Nanoparticles Functionalized by a Chiral Drug

Inorganic chiral nanoparticles are attracting more and more attention due to their peculiar optical properties and potential biological applications, such as bioimaging, therapeutics, and diagnostics. Among inorganic chiral nanoparticles, gold chiral nanostructures were demonstrated to be very interesting in this context, with good physical chemical stability and also the possibility to decorate the surface, improving biomedical application as the interaction with the bio-systems. Gold (Au) nanostructures were synthesized according to a seed-mediated procedure which envisages the use of cetyltrimethylammonium bromide (CTAB) as the capping agent and L- and D-cysteine to promote chirality. Au nanostructures have been demonstrated to have opposite circular dichroism signals depending on the amino acid enantiomer used during the synthesis. Then, a procedure to decorate the Au surface with penicillamine, a drug used for the treatment of Wilson's disease, was developed. The composite material of gold nanoparticles/penicillamine was characterized using electron microscopy, and the penicillamine functionalization was monitored by means of UV-Visible, Raman, and infrared spectroscopy, highlighting the formation of the Au-S bond. Furthermore, electron circular dichroism was used to monitor the chirality of the synthesized nanostructures and it was demonstrated that both penicillamine enantiomers can be successfully bonded with both the enantiomers of the gold nanostructures without affecting gold nanoparticles' chirality. The effective modification of nanostructures' surfaces via penicillamine introduction allowed us to address the important issue of controlling chirality and surface properties in the chiral nano-system.

Chiral inorganic nanomaterials for biological applications

Chiral nanomaterials in biology play indispensable roles in maintaining numerous physiological processes, such as signaling, site-specific catalysis, transport, protection, and synthesis. Like natural chiral nanomaterials, chiral inorganic nanomaterials can also be established with similar size, charge, surface properties, and morphology. However, chiral inorganic nanomaterials usually exhibit extraordinary properties that are different from those of organic materials, such as high g-factor values, broad distribution range, and symmetrical mirror configurations. Because of these unique characteristics, there is great potential for application in the fields of biosensing, drug delivery, early diagnosis, bio-imaging, and disease therapy. Related research is summarized and discussed in this review to showcase the bio-functions and bio-applications of chiral inorganic nanomaterials, including the construction methods, classification and properties, and biological applications of chiral inorganic nanomaterials. Moreover, the deficiencies in existing studies are noted, and future development is prospected. This review will provide helpful guidance for constructing chiral inorganic nanomaterials with specific bio-functions for problem solving in living systems.

Chiral nanomaterials for biosensing, bioimaging, and disease therapies

Chiral plasmonic nanomaterials for biosensing, bioimaging and disease therapy.