Biosynthesized Gold Nanoclusters and Iron Complexes as Scaffolds for Multimodal Cancer Bioimaging

Targeted self-assembled anti-NFκB AuNCs-aptamer nanoplatform for precise theranostics via tailored follicle regeneration

NFκB is a vital transcription factor for the regulation of hair follicle cycle. As a therapeutic target, NFκB is specifically blocked by RNA aptamer with negligible side effects, but the targeted transmembrane transport of anti-NFκB aptamer remains a challenge due to its negative charge under physiological conditions. In this study, taking advantage of the depilation-induced oxidative stress microenvironment (OSM), it was confirmed for the first time that self-assembled gold nanoclusters and aptamer (AuNCs-Aptamer) complexes formed in the skin and enhanced the therapeutic effect of anti-NFκB aptamer drugs, effectively blocking the NFκB-mediated inflammatory response and inhibiting hair follicle regeneration. The hematoxylin-eosin (HE) staining of tissue section and hematology analysis demonstrated that OSM-responsive self-assembled AuNCs-Aptamer caused no toxicity to the living organism. Moreover, self-assembly occurred only in the oxidative stress-injured skin cells rather than the normal cells, which revealed that this self-assembly was a targeted, safe and effective therapy for hypertrichosis.

From detection to elimination: iron-based nanomaterials driving tumor imaging and advanced therapies

Iron-based nanomaterials (INMs), due to their particular magnetic property, excellent biocompatibility, and functionality, have been developed into powerful tools in both tumor diagnosis and therapy. We give an overview here on how INMs such as iron oxide nanoparticles, element-doped nanocomposites, and iron-based organic frameworks (MOFs) display versatility for tumor imaging and therapy improvement. In terms of imaging, INMs improve the sensitivity and accuracy of techniques such as magnetic resonance imaging (MRI) and photoacoustic imaging (PAI) and support the development of multimodal imaging platforms. Regarding treatment, INMs play a key role in advanced strategies such as immunotherapy, magnetic hyperthermia, and synergistic combination therapy, which effectively overcome tumor-induced drug resistance and reduce systemic toxicity. The integration of INMs with artificial intelligence (AI) and radiomics further expands its capabilities for precise tumor identification, and treatment optimization, and amplifies treatment monitoring. INMs now link materials science with advanced computing and clinical innovations to enable next-generation cancer diagnostics and therapeutics.

Mitochondria-Targeted Gold Biometallization for Photoacoustically Visualized Photothermal Cancer Therapy

Subcellular biomineralization systems with cellular intervention functions have shown great potential in cancer theranostic applications. However, the lack of subcellular specificity, high ion concentrations, and long incubation time required for biomineralization still limit its in vivo therapeutic efficacy. Herein, we report a mitochondria-targeted polymer-gold complex (TPPM-Au) to realize mitochondrial biometallization, which involves analogous mechanisms during biomineralization, for cancer treatment in vivo. The TPP-containing TPPM-Au delivered more Au3+ selectively into the mitochondria of cancer cells than normal cells, rapidly mineralizing to gold nanoparticles (GNPs) and consuming a large amount of the antioxidant glutathione (GSH). The formed GNPs can further continue consuming GSH with the atomic economy by forming Au-S with GSH, which further results in the accumulation of reactive oxygen species (ROS), thereby impairing mitochondrial function and inducing cell apoptosis. More importantly, TPPM-Au is capable of having superior tumor-penetrating, excellent photothermal and photoacoustic properties, endowing it with the ability to inhibit tumor growth through spatiotemporally monitorable mitochondria-targeted biometallization and photothermal therapy. The mitochondria-targeted gold biometallization theranostic platform provides insight into the application of subcellularly targeted biometallization or biomineralization in cancer therapy.

Bio-responsive Au-miR-183 inhibitor enhances immunotherapy in hepatocellular carcinoma by inducing immunogenic cell death

The treatment of advanced hepatocellular carcinoma (HCC) is limited, and immunotherapy is the current research focus of multi-disciplinary collaborative comprehensive treatment of HCC. Herein, we constructed a bio-responsive Au-miR-183 inhibitor (Au@miR-183i) delivery system targeting liver cancer stem cells (LCSCs), and adopted the strategy of combining αPD-L1 immunotherapy. The multifunctional Au@miR-183i nanocomplexes (NCs), which self-assemble based on the tumor microenvironment, consume NADPH and H2O2, leading to redox homeostasis disturbance, ROS accumulation, regulation of the LCSC niche, and induction of stemness regression. Moreover, self-assembled Au@miR-183i NCs specifically target the delivery of miR-183i to LCSCs, triggering the immunogenic cell death (ICD) effect, promoting the maturation of dendritic cells, inducing infiltration of CD8+ T cells, and facilitating the transformation of 'cold' tumors into 'hot' tumors. More importantly, consistent with the results in vitro, Au@miR-183i NCs demonstrated effective tumor targeting and strong ICD induction in vivo, assisted in enhancing αPD-L1 immunotherapy, and activated a robust systemic anti-tumor immune response in tumor-bearing mouse models. Overall, we provide a simple and universal therapeutic strategy by constructing a multifunctional bio-responsive Au@miR-183i NCs delivery system with LCSC targeting capability. Furthermore, nanocomplex-based ICD inducers have great promise in enhancing anti-tumor immunity and the PD-1/PD-L1 blocking efficacy in HCC, which provides a theoretical basis for effectively eliminating LCSCs and achieving a high-efficiency synergistic treatment strategy for HCC.

Designing a Mitochondria-Targeted Theranostic Cyclometalated Iridium(III) Complex: Overcoming Cisplatin Resistance and Inhibiting Tumor Metastasis through Necroptosis and Immune Response

To develop a potential theranostic metal agent to reverse the resistance of cancer cells to cisplatin and effectively inhibit tumor growth and metastasis, we proposed to design a cyclometalated iridium (Ir) complex based on the properties of the tumor environment (TME). To the end, we designed and synthesized a series of Ir(III) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes by modifying the hydrogen atom(s) of the N-3 position of 2-hydroxy-1-naphthaldehyde thiosemicarbazone compounds and the structure of cyclometalated Ir(III) dimers and then investigated their structure-activity and structure-fluorescence relationships to obtain an Ir(III) complex (Ir5) with remarkable fluorescence and cytotoxicity to cancer cells. Ir5 not only possesses mitochondria-targeted properties but also overcomes cisplatin resistance and effectively inhibits tumor growth and metastasis in vivo. Besides, we confirmed the anticancer mechanisms of Ir5 acting on different components in the TME: directly killing liver cancer cells by inducing necroptosis and activating the necroptosis-related immune response.

Intratumoral Biosynthesis of Gold Nanoclusters by Pancreatic Cancer to Overcome Delivery Barriers to Radiosensitization

Nanoparticle delivery to solid tumors is a prime challenge in nanomedicine. Here, we approach this challenge through the lens of biogeochemistry, the field that studies the flow of chemical elements within ecosystems as manipulated by living cellular organisms and their environments. We leverage biogeochemistry concepts related to gold cycling against pancreatic cancer, considering mammalian organisms as drivers for gold nanoparticle biosynthesis. Sequestration of gold nanoparticles within tumors has been demonstrated as an effective strategy to enhance radiotherapy; however, the desmoplasia of pancreatic cancer impedes nanoparticle delivery. Our strategy overcomes this barrier by applying an atomic-scale agent, ionic gold, for intratumoral gold nanoparticle biosynthesis. Our comprehensive studies showed the cancer-specific synthesis of gold nanoparticles from externally delivered gold ions in vitro and in a murine pancreatic cancer model in vivo; a substantial colocalization of gold nanoparticles (GNPs) with cancer cell nuclei in vitro and in vivo; a strong radiosensitization effect by the intracellularly synthesized GNPs; a uniform distribution of in situ synthesized GNPs throughout the tumor volume; a nearly 40-day total suppression of tumor growth in animal models of pancreatic cancer treated with a combination of gold ions and radiation that was also associated with a significantly higher median survival versus radiation alone (235 vs 102 days, respectively).

Ultrafast Subcellular Biolabeling and Bioresponsive Real-Time Monitoring for Targeting Cancer Theranostics

Cell heterogeneity poses a formidable challenge for tumor theranostics, requiring high-resolution strategies for intercellular bioanalysis between single cells. Nanoelectrode-based electrochemical analysis has attracted much attention due to its advantages of label-free characteristics, relatively low cost, and ultra-high resolution for single-cell analysis. Here, we have designed and developed a subcellular biolabeling and bioresponsive real-time monitoring strategy for precise bioimaging-guided cancer diagnosis and theranostics. Our observations revealed the apparent intracellular migration of biosynthetic Au nanoclusters (Au NCs) at different subcellular locations, i.e., from the mitochondria to the mitochondrion-free region in the cytoplasm, which may be helpful for controlling over the biosynthesis of Au NCs. Considering the precise biolabeling advantage of the intracellular biosynthetic Au NCs for biomedical imaging of cancers, it is important to realize the biosynthetic Au NC-enabled precise control in real-time theranostics of cancer cells. Therefore, this work raises the possibility to achieve subcellular monitoring of H2O2 for targeting cancer theranostics, thereby providing a new way to explore the underlying mechanism and imaging-guided tumor theranostics.

Harnessing Hafnium-Based Nanomaterials for Cancer Diagnosis and Therapy

With the rapid development of nanotechnology and nanomedicine, there are great interests in employing nanomaterials to improve the efficiency of disease diagnosis and treatment. The clinical translation of hafnium oxide (HfO2 ), commercially namedas NBTXR3, as a new kind of nanoradiosensitizer for radiotherapy (RT) of cancers has aroused extensive interest in researches on Hf-based nanomaterials for biomedical application. In the past 20 years, Hf-based nanomaterials have emerged as potential and important nanomedicine for computed tomography (CT)-involved bioimaging and RT-associated cancer treatment due to their excellent electronic structures and intrinsic physiochemical properties. In this review, a bibliometric analysis method is employed to summarize the progress on the synthesis technology of various Hf-based nanomaterials, including HfO2 , HfO2 -based compounds, and Hf-organic ligand coordination hybrids, such as metal-organic frameworks or nanoscaled coordination polymers. Moreover, current states in the application of Hf-based CT-involved contrasts for tissue imaging or cancer diagnosis are reviewed in detail. Importantly, the recent advances in Hf-based nanomaterials-mediated radiosensitization and synergistic RT with other current mainstream treatments are also generalized. Finally, current challenges and future perspectives of Hf-based nanomaterials with a view to maximize their great potential in the research of translational medicine are also discussed.

Facile One-Pot Green Synthesis of Magneto-Luminescent Bimetallic Nanocomposites with Potential as Dual Imaging Agent

Nanocomposites serving as dual (bimodal) probes have great potential in the field of bio-imaging. Here, we developed a simple one-pot synthesis for the reproducible generation of new luminescent and magnetically active bimetallic nanocomposites. The developed one-pot synthesis was performed in a sequential manner and obeys the principles of green chemistry. Briefly, bovine serum albumin (BSA) was exploited to uptake Au (III) and Fe (II)/Fe (III) ions simultaneously. Then, Au (III) ions were transformed to luminescent Au nanoclusters embedded in BSA (AuNCs-BSA) and majority of Fe ions were bio-embedded into superparamagnetic iron oxide nanoparticles (SPIONs) by the alkalization of the reaction medium. The resulting nanocomposites, AuNCs-BSA-SPIONs, represent a bimodal nanoprobe. Scanning transmission electron microscopy (STEM) imaging visualized nanostructures with sizes in units of nanometres that were arranged into aggregates. Mössbauer spectroscopy gave direct evidence regarding SPION presence. The potential applicability of these bimodal nanoprobes was verified by the measurement of their luminescent features as well as magnetic resonance (MR) imaging and relaxometry. It appears that these magneto-luminescent nanocomposites were able to compete with commercial MRI contrast agents as MR displays the beneficial property of bright luminescence of around 656 nm (fluorescence quantum yield of 6.2 ± 0.2%). The biocompatibility of the AuNCs-BSA-SPIONs nanocomposite has been tested and its long-term stability validated.

Ultraprecise Real-Time Monitoring of Single Cells in Tumors in Response to Metal Ion-Mediated RNA Delivery

With the deepening of cancer clinical research, miRNAs provide new ideas for molecular diagnosis and treatment of tumors. Improving the molecular delivery efficiency of miRNA is the key to the success of miRNA therapy. We have established self-assembly diagnosis and treatment technologies that can be used to achieve accurate targeting and "cargo" delivery at the cellular level. This technology builds a miRNA (let-7a) delivery system based on metal precursor [Au(III) and Fe(II)]-mediated tumor microenvironmental response to realize the self-assembly of Au&Fe-miRNA complexes for precise real-time imaging of tumor cells and targeted therapy. To accurately measure the changes in reactive oxygen species during complex formation in real time at the single-cell level, we employed small-size nanoscale devices as analytical tools. This study proposes an electrochemical sensor based on carbon fiber electrodes for ultraprecise and multiple monitoring of metal-ion-mediated miRNA delivery systems, precisely realizing targeted tracking of tumors and effective intervention inhibition.

Title: Advances of Gold Nanoclusters for Bioimaging

Gold nanoclusters (AuNCs) have become a promising material for bioimaging detection because of their tunable photoluminescence, large Stokes shift, low photobleaching, and good biocompatibility. Last decade, great efforts have been made to develop AuNCs for enhanced imaging contrast and multimodal imaging. Herein, an updated overview of recent advances in AuNCs was present for visible fluorescence (FL) imaging, near-infrared fluorescence (NIR-FL) imaging, two-photon near-infrared fluorescence (TP-NIR-FL) imaging, computed tomography (CT) imaging, positron emission tomography (PET) imaging, magnetic resonance imaging (MRI), and photoacoustic (PA) imaging. The justification of AuNCs applied in bioimaging mentioned above applications was discussed, the performance location of different AuNCs were summarized and highlighted in an unified parameter coordinate system of corresponding bioimaging, and the current challenges, research frontiers, and prospects of AuNCs in bioimaging were discussed. This review will bring new insights into the future development of AuNCs in bio-diagnostic imaging.

Prospecting Cellular Gold Nanoparticle Biomineralization as a Viable Alternative to Prefabricated Gold Nanoparticles

Gold nanoparticles (GNPs) have shown considerable potential in a vast number of biomedical applications. However, currently there are no clinically approved injectable GNP formulations. Conversely, gold salts have been used in the clinic for nearly a century. Further, there is evidence of GNP formation in patients treated with gold salts (i.e., chrysiasis). Recent reports evaluating this phenomenon in human cells and in murine models indicate that the use of gold ions for in situ formation of theranostic GNPs could greatly improve the delivery within dense biological tissues, increase efficiency of intracellular gold uptake, and specificity of GNP formation within cancer cells. These attributes in combination with safe clinical application of gold salts make this process a viable strategy for clinical translation. Here, the first summary of the current knowledge related to GNP biomineralization in mammalian cells is provided along with critical assessment of potential biomedical applications of this newly emergent field.

Progress on photocatalytic semiconductor hybrids for bacterial inactivation

Due to its use of green and renewable energy and negligible bacterial resistance, photocatalytic bacterial inactivation is to be considered a promising sterilization process. Herein, we explore the relevant mechanisms of the photoinduced process on the active sites of semiconductors with an emphasis on the active sites of semiconductors, the photoexcited electron transfer, ROS-induced toxicity and interactions between semiconductors and bacteria. Pristine semiconductors such as metal oxides (TiO₂ and ZnO) have been widely reported; however, they suffer some drawbacks such as narrow optical response and high photogenerated carrier recombination. Herein, some typical modification strategies will be discussed including noble metal doping, ion doping, hybrid heterojunctions and dye sensitization. Besides, the biosafety and biocompatibility issues of semiconductor materials are also considered for the evaluation of their potential for further biomedical applications. Furthermore, 2D materials have become promising candidates in recent years due to their wide optical response to NIR light, superior antibacterial activity and favorable biocompatibility. Besides, the current research limitations and challenges are illustrated to introduce the appealing directions and design considerations for the future development of photocatalytic semiconductors for antibacterial applications.

A Simplistic Single-Step Method for Preparing Biomimetic Nanoparticles from Endogenous Biomaterials

Many works utilize products isolated from nature as capping agents to functionalize gold nanoparticles for targeting and therapeutic applications. Some of the most advanced of these strategies utilize complex multicomponent biomaterials, such as whole cell-membranes, for nanoparticle functionalization strategies for evading or initializing immune response as well as for targeting. Strategies like these, wherein whole cell membrane is utilized for functionalization, take advantage of the complexity of the protein-lipid content and organization, which cells normally use for communication and interaction (instilling these capacities to nanoparticle vectors). Many approaches for achieving this in functionalizing the surface of nanoparticles rely on multistep processes, which necessitate the addition and then removal of synthetic molecules, heating, or pH modifications. These processes can have deleterious modifying effects on the functionalizing biomolecules, resulting in loss of product and time during each purification step, as well as potentially changing the biomolecule functionality toward a nondesirable effect. Here, we describe methods for forming gold nanoparticles at room temperature in a single step, functionalized with proteins, using nicotinamide adenine dinucleotide (NADH). This process enables formation of nanoparticles that can be functionalized by individual proteins (demonstrated with FBS) or whole cells membrane (extracted from B16F10 cells). This work is derivative from observations found in the literature by us and others, that mammalian cells are capable of producing gold nanoparticles from ionic gold without the supplementation of chemical species. The products of this single-step synthesis described herein have been optimized to maintain biomolecule integrity and so that there are no further purification steps required. To characterize the nanoparticles in terms of their shape, size, surface functionality, and biomolecule integrity throughout development, we employed light-based spectroscopy techniques, molecular modeling, electron microscopy, light scattering, and gel electrophoresis techniques. In order to compare the optimized biomolecule-functionalized nanoparticles against current standards (which require synthetic linkers, heating, or pH manipulation), we employed metabolic and live/dead assays as well as light-based microscopy/spectroscopy in vitro. In comparing our synthetic process against others for forming gold nanoparticles functionalized with complex biomolecule components (whole-cell membrane), we found that this process had superior particle internalization. Our strategy has similar outlets for application to these other works, however, because this process is entirely reliant on endogenous biomaterials and has additional potential.

Rapid and label-free cancer theranostics via in situ bio-self-assembled DNA-gold nanostructures loaded exosomes

Chemically engineered nanomaterials have been extensively used in early tumor detection and cancer therapy. Despite the promise shown, their chemical or exogenous nature hinders their application due to their unknown adverse effects. Herein, using a cancer cell environment, fluorescent DNA-gold nanostructures were bio-self-assembled through simple incubation of DNA and Au solutions with cancer cells. In situ, ex vivo, bio-responsive self-assembly of ring-shaped DNA-Au nanostructures is reported for the first time. Subsequently, the exosomes released by the above-mentioned cancer cells were found to carry the self-assembled DNA-Au nanostructures, exhibiting strong in vivo dual fluorescence properties. Interestingly, these exosomes could be immediately taken up in vitro by their parent cells, reaching the nucleus within 10 min after incubation. Taking advantage of the unique endogenous properties of exosomes, and their advanced cargo delivery capacity, we further exploited the DNA-Au nanostructure loaded exosomes with mitoxantrone for accurate cancer theranostics. The in vitro and in vivo results showed that the exosomes could effectively deliver the drug cargo to cancerous cells, hence, displaying an enhanced targeting effect towards parent cancer cells, and a synergistic tumor inhibition effect, while showing great biocompatibility towards normal cells and vital organs. Hence, exosomes carrying the in situ bio-self-assembled DNA-Au nanostructures could be an outstanding delivery system for dye-free targeted cancer detection and therapy.

Self-assembled Au4Cu4/Au25 NCs@liposome tumor nanotheranostics with PT/fluorescence imaging-guided synergetic PTT/PDT

Exploring and developing a new type of nanoplatform with diagnosis and treatment to effectively cure tumors and reduce side effects has become a hot spot for researchers and is of great significance. Herein, a cancer theranostic nanoplatform with dual-imaging, dual-phototherapy and laser-responsiveness to tumor microenvironment was successfully assembled by liposome (Lip) co-loaded with oil-soluble Au₄Cu₄ nanoclusters (NCs) and water-soluble Au₂₅ NCs via a simple film hydration method and subsequent extraction process. The prepared Au₄Cu₄/Au₂₅@Lip nanoplatform with core-shell structure and about 50 nm of uniform sphere shape presented highly biocompatible, stability and passive targeting due to the enhanced permeability and retention (EPR) effect. Furthermore, the Lip composed of lecithin and cholesterol has good affinity with the cell membrane, which can realize the effective accumulation of photosensitizers at the tumor site, so that improving phototherapy effect and reducing the damage to normal tissue. The loaded oil-soluble Au₄Cu₄ NCs were firstly and pleasantly surprised to find possessed not only ideal photodynamic effect, but also preferable catalysis towards endogenous hydrogen peroxide (H₂O₂) decomposition to produce oxygen (O₂) for improving the tumor hypoxic environment besides the excellent photoluminescence ability while the water-soluble Au₂₅ NCs own outstanding photothermogenesis effect and also photoluminescence performance. The in vitro and in vivo experiment results proved that in the Au₄Cu₄/Au₂₅@Lip nanoplatform, the performances of both NCs were complementary, which presenting considerable photothermal/fluorescence imaging (PTI/FI)-guided synergistic photothermal therapy (PTT)/O₂-enhanced photodynamic therapy (PDT) effect for the tumor under the irradiation of near infrared (NIR) laser. This work provides a useful inspiration and paves a new way for the assembly of NCs or namomaterials with different properties into an integrated anti-tumor theranostic nanoplatform.

Tumor-targeting inorganic nanomaterials synthesized by living cells

Inorganic nanomaterials (NMs) have shown potential application in tumor-targeting theranostics, owing to their unique physicochemical properties. Some living cells in nature can absorb surrounding ions in the environment and then convert them into nanomaterials after a series of intracellular/extracellular biochemical reactions. Inspired by that, a variety of living cells have been used as biofactories to produce metallic/metallic alloy NMs, metalloid NMs, oxide NMs and chalcogenide NMs, which are usually automatically capped with biomolecules originating from the living cells, benefitting their tumor-targeting applications. In this review, we summarize the biosynthesis of inorganic nanomaterials in different types of living cells including bacteria, fungi, plant cells and animal cells, accompanied by their application in tumor-targeting theranostics. The mechanisms involving inorganic-ion bioreduction and detoxification as well as biomineralization are emphasized. Based on the mechanisms, we describe the size and morphology control of the products via the modulation of precursor ion concentration, pH, temperature, and incubation time, as well as cell metabolism by a genetic engineering strategy. The strengths and weaknesses of these biosynthetic processes are compared in terms of the controllability, scalability and cooperativity during applications. Future research in this area will add to the diversity of available inorganic nanomaterials as well as their quality and biosafety.

In situ self-assembled Ag-Fe3O4 nanoclusters in exosomes for cancer diagnosis

Recently, exosomes have gained attention as an effective tool for early cancer detection. Almost all types of cells release exosomes, making them substantially important for disease diagnosis. In this study, we have utilized HepG2 cancer cells for the in situ biosynthesis of silver and iron oxide nanoclusters (NCs) from their respective salts (i.e., AgNO3 and FeCl2, respectively) in the presence of glutathione (GSH). The self-assembled biosynthesized silver and iron NCs were readily loaded on exosomes as payloads and secreted into the cell culture medium. The cargo loaded exosomes were then isolated and characterized by electron microscopy for nano-silver and iron oxide NC confirmation. Ag NCs have potential as a fluorescent probe and Fe3O4 NCs as a contrast agent for CT and MRI. Furthermore, these isolated exosomes from HepG2 cancer cells have a significant influence on cellular uptake and cell viability when exposed to both HepG2 and U87 cancer cells. These findings demonstrate that the biocompatible nature of these self-assembled NCs loaded on exosomes could be utilized to bioimage cancer in the initial stages through fluorescence imaging.

Intratumoral generation of photothermal gold nanoparticles through a vectorized biomineralization of ionic gold

Various cancer cells have been demonstrated to have the capacity to form plasmonic gold nanoparticles when chloroauric acid is introduced to their cellular microenvironment. But their biomedical applications are limited, particularly considering the millimolar concentrations and longer incubation period of ionic gold. Here, we describe a simplistic method of intracellular biomineralization to produce plasmonic gold nanoparticles at micromolar concentrations within 30 min of application utilizing polyethylene glycol as delivery vector for ionic gold. We have characterized this process for intracellular gold nanoparticle formation, which progressively accumulates proteins as the ionic gold clusters migrate to the nucleus. This nano-vectorized application of ionic gold emphasizes its potential biomedical opportunities while reducing the quantity of ionic gold and required incubation time. To demonstrate its biomedical potential, we further induce in-situ biosynthesis of gold nanoparticles within MCF7 tumor mouse xenografts which is followed by its photothermal remediation.

Blood-brain barrier amenable gold nanoparticles biofabrication in aged cell culture medium

Green fabrication of nanoscale materials is highly desirable because of associated adverse effects with conventional nanomaterial biomedical applications. Moreover, the higher selective nature of the blood-brain barrier (BBB) limits the brain ailments treatment through conventional chemotherapy, thus providing room for nanotechnology-based modalities for BBB traversing. In this contribution, we have biosynthesized gold nanoparticles from the HAuCl4 solution in the aged cells culture medium. This approach is highly facile without any other chemical utilization. The cell culture medium age and cell number can tune the Au nanoparticles (AuNPs) size from 2 to several hundred nm. The 24 h MTT assay and cell uptake studies in vitro and murine models' vital organs (liver, kidney, spleen, lung, and heart) study up to 48 h demonstrated that biosynthesized AuNPs were biocompatible and BBB amenable. Interestingly, the transferrin and cell culture medium isolated proteins were found factors responsible for HAuCl4 solution biomineralization and size control. Moreover, the protein corona on biosynthesized AuNPs could help them traverse BBB both in vitro and in vivo, suggesting their potential applications for brain disease theranostics. In conclusion, the biosynthesis of AuNPs from aged cells medium is highly facile, green, and biocompatible for brain disease theranostics.

Precise therapeutic effect of self-assembling gold nanocluster-PTEN complexes on an orthotropic model of liver cancer

PURPOSE

Presently, liver cancer is still one of the malignant tumors with high mortality. As far as the treatment of liver cancer is concerned, the most effective method is still liver transplantation. But every year, many liver cancer patients die from the lack of a proper liver transplant, or from waiting for a liver transplant. Therefore, it is very important to find new and effective treatment for patients with liver cancer.

METHODS

Herein, the cell model and the orthotropic liver tumor mice model have been performed to verify the results of our treatment. We found that the in situ synthesized gold nanocluster-PTEN (GNC-PTEN) complexes can effectively target and realize the fluorescence imaging of the liver tumor.

RESULTS

GNC-PTEN complexes could inhibit the proliferation, invasion, and metastasis of liver cancer cells. And the results also showed that GNC-PTEN complexes could be well targeted liver tumor at 6 h and the liver tumor in mice group treated with GNC-PTEN complexes almost disappeared.

CONCLUSION

This is a simply and effectively method to realize liver cancer imaging and inhibition. This may raise the possibility for the accurate image/diagnosis and simultaneously efficient treatment of liver cancer in the relevant clinic application.

Recent advances in ultra-small fluorescent Au nanoclusters toward oncological research

Au nanoclusters possess a series of excellent properties owing to their size being comparable to the Fermi wavelength of electrons. For example, they show excellent biocompatibility, optical stability, large Stokes shift, intense size-dependent emission and monodispersion, and thus could effectively compensate for the shortcomings of traditional organic fluorescent dyes and fluorescent quantum. In this review, we detail the latest developments of Au nanoclusters employed in the field of biomedicine, especially in oncology research, by summarizing the application of imaging, sensing and drug delivery based on their excellent luminescent properties and unique structural features. We also discuss the significant work relating to Au NCs that now is being devoted in other therapeutic strategies, such as radiotherapy, photothermal therapy and photodynamic therapy, for example. It is anticipated that this review will provide new insights and theoretical guidance to allow the advantages of Au nanoclusters to be realized in oncotherapy.

In situ biosynthesized gold nanoclusters inhibiting cancer development via the PI3K-AKT signaling pathway

Nanomaterials have made great breakthroughs in drug delivery. However, in previous studies, nanomaterials have been mostly used as vehicles to transport drugs into tumors. Herein, we first found that the in situ biosynthesized gold nanoparticles (Au NCs) can inhibit cancer development via the inhibition of some signaling pathways. Classical cell phenotypic assay tests and orthotropic liver tumor model both showed that the in situ biosynthesized Au NCs could inhibit tumor development. With the help of the RNA-seq analysis, we found that the in situ biosynthesized Au NCs could significantly inhibit the PI3K-AKT signaling pathway, thus effectively impeding tumor development. This facile and effective tumor targeting theranostics in vivo can effectively cure cancers in future clinical applications.

Multifunctional Magnetic Gold Nanomaterials for Cancer

The integration of multiple imaging and therapeutic agents into a customizable nanoplatform for accurate identification and rapid prevention of cancer is attracting great attention. Among the available theranostic nanosystems, magnetic gold nanoparticles are particularly promising as they exhibit unique physicochemical properties that can support multiple functions, including cancer diagnosis by magnetic resonance imaging, X-ray computed tomography, Raman and photoacoustic imaging, drug delivery, and plasmonic photothermal and photodynamic therapies. This review gives an overview of recent advances in the fabrication of multifunctional gold nanohybrids with magnetic and optical properties and their successful demonstration in multimodal imaging and therapy of cancer. Concerns around toxicity of these nanomaterials are also discussed in view of an imminent transition to clinical practice.

Nano in nano: Biosynthesized gold and iron nanoclusters cargo neoplastic exosomes for cancer status biomarking

Timely detection is crucial for successful treatment of cancer. The current study describes a new approach that involves utilization of the tumor cell environment for bioimaging with in-situ biosynthesized nanoscale gold and iron probes and subsequent dissemination of Au-Fe nanoclusters from cargo exosomes within the circulatory system. We have isolated the Au-Fe cargo exosomes from the blood of the treated murine models after in situ biosyntheses from their respective pre-ionic solutions (HAuCl₄, FeCl₂), whereas Na₂SeO₃ supplementation added into Au lethal effect. The microarray data of various differentially expressed genes revealed the up-regulated tumor ablation and metal binding genes in SGC-7901 cell lines after treatment with Au-Fe-Se triplet ionic solution. The isolation of Au-Fe nanoclusters cargo exosomes (nano in nano) after secretion from deeply seated tumors may help in early diagnosis and reveal the tumor ablation status during and after the relevant treatment like radio-chemo therapies et al.

Real-Time Multimodal Bioimaging of Cancer Cells and Exosomes through Biosynthesized Iridium and Iron Nanoclusters

Multimodal bioimaging is a powerful tool for visualizing the abnormal state at the target site of the related disease. In this study, we used multimodal imaging techniques such as computed tomography, fluorescence, and magnetic resonance imaging to improve early and precise diagnosis of tumor. Herein, we reported the facile in situ biosynthesis of iridium and iron oxide nanoclusters (NCs) in cancer cells or tumor tissue. These NCs are used as a multimodal bioimaging probe to improve the image sensitivity and specificity toward the tumor. These NCs are applied for the in vivo multimodal imaging in the form of an imaging probe capable of enhancing the sensitivity of the image and specificity toward the tumor tissue. Our observation demonstrates that highly luminescent and magnetic NCs are not only biocompatible but also tumor-targeted because NC formation does not take place in normal cells and tissues. In addition, we isolated exosomes and the biosynthesized NCs internalized within exosomes, and these exosomes can be used as cancer biomarkers.

Magnetite-Gold nanohybrids as ideal all-in-one platforms for theranostics

High-quality, 25 nm octahedral-shaped Fe3O4 magnetite nanocrystals are epitaxially grown on 9 nm Au seed nanoparticles using a modified wet-chemical synthesis. These Fe3O4-Au Janus nanoparticles exhibit bulk-like magnetic properties. Due to their high magnetization and octahedral shape, the hybrids show superior in vitro and in vivo T2 relaxivity for magnetic resonance imaging as compared to other types of Fe3O4-Au hybrids and commercial contrast agents. The nanoparticles provide two functional surfaces for theranostic applications. For the first time, Fe3O4-Au hybrids are conjugated with two fluorescent dyes or the combination of drug and dye allowing the simultaneous tracking of the nanoparticle vehicle and the drug cargo in vitro and in vivo. The delivery to tumors and payload release are demonstrated in real time by intravital microscopy. Replacing the dyes by cell-specific molecules and drugs makes the Fe3O4-Au hybrids a unique all-in-one platform for theranostics.

Design and mechanistic study of a novel gold nanocluster-based drug delivery system

Chemically-triggered drug delivery systems (DDSs) have been extensively studied as they do not require specialized equipment to deliver the drug and can deeply penetrate human tissue. However, their syntheses are complicated and they tend to be cytotoxic, which restricts their clinical utility. In this work, the self-regulated drug loading and release capabilities of peptide-protected gold nanoclusters (Pep-Au NCs) are investigated using vancomycin (Van) as the model drug. Gold nanoclusters (Au NCs) coated with a custom-designed pentapeptide are synthesized as drug delivery nanocarriers and loaded with Van - a spontaneous process reliant on the specific binding between Van and the custom-designed peptide. The Van-loaded Au NCs show comparable antimicrobial activity with Van on its own, and the number of Van released by the Pep-Au NCs is found to be proportional to the amount of bacteria present. The controlled nature of the Van release is very encouraging, and predominantly due to the stronger binding affinity of Van with bacteria than that with Au NCs. In addition, these fluorescent Au NCs could also be used to construct temperature sensors, which enable the in vitro and in vivo bioimaging.

Adjusting the Linear Range of Au-MOF Fluorescent Probes for Real-Time Analyzing Intracellular GSH in Living Cells

A series of Au-loaded metal-organic frameworks (MOFs) were synthesized in this study and further employed for real-time quantitative analysis of intracellular glutathione (GSH) level. Different linear ranges can be acquired by altering the size of gold and MOF particles, or adjusting the proportion of 2-aminoterephthalic acid/1,4-benzenedicarboxylate linkers, which is also observed on fluorescein isothiocyanate-attached Au-MOFs. Further study reveals that the flexible molecular chain of GSH with the -COOH/-NH₂ and -SH terminals may readily tie on relevant gold nanoparticles through its -NH₂/-COOH groups, which then restricts the intramolecular motions of fluorescence probes and thus induces marked fluorescence enhancement. On the basis of these observations, the intracellular GSH levels of different cells including L02 cells, Hela, and U87 as well as HepG2 cancer cells can be rapidly evaluated by these Au-MOF probes.

Glycyrrhetinic Acid Functionalized Graphene Oxide for Mitochondria Targeting and Cancer Treatment In Vivo

Mitochondria-mediated apoptosis (MMA) is a preferential option for cancer therapy due to the presence of cell-suicide factors in mitochondria, however, low permeability of mitochondria is a bottleneck for targeting drug delivery. In this paper, glycyrrhetinic acid (GA), a natural product from Glycyrrhiza glabra, is found to be a novel mitochondria targeting ligand, which can improve mitochondrial permeability and enhance the drug uptake of mitochondria. GA-functionalized graphene oxide (GO) is prepared and used as an effective carrier for targeted delivery of doxorubicin into mitochondria. The detailed in vitro and in vivo mechanism study shows that GA-functionalized GO causes a decrease in mitochondrial membrane potential and activates the MMA pathway. The GA-functionalized drug delivery system demonstrates highly improved apoptosis induction ability and anticancer efficacy compared to the non-GA-functionalized nanocarrier delivery system. The GA-functionalized nanocarrier also shows low toxicity, suggesting that it can be a useful tool for drug delivery.

Mammalian cells: a unique scaffold forin situbiosynthesis of metallic nanomaterials and biomedical applications

Nanoscale materials biosynthesis by using mammalian scaffold is green and highly biocompatible.

In Vivo Biosynthesized Zinc and Iron Oxide Nanoclusters for High Spatiotemporal Dual-Modality Bioimaging of Alzheimer's Disease

Alzheimer's disease is still incurable and neurodegenerative, and there is a lack of detection methods with high sensitivity and specificity. In this study, by taking different month old Alzheimer's mice as models, we have explored the possibility of the target bioimaging of diseased sites through the initial injection of zinc gluconate solution into Alzheimer's model mice post-tail vein and then the combination of another injection of ferrous chloride (FeCl₂) solution into the same Alzheimer's model mice post-stomach. Our observations indicate that both zinc gluconate solution and FeCl₂ solution could cross the blood-brain barrier (BBB) to biosynthesize the fluorescent zinc oxide nanoclusters and magnetic iron oxide nanoclusters, respectively, in the lesion areas of the AD model mice, thus enabling high spatiotemporal dual-modality bioimaging (i.e., including fluorescence bioimaging (FL) and magnetic resonance imaging (MRI)) of Alzheimer's disease for the first time. The result presents a novel promising strategy for the rapid and early diagnosis of Alzheimer's disease.

Two-Photon Imaging of 3D Organization of Bimetallic AuAg Nanoclusters in DNA Matrix

We report on two-photon excitation properties of small silver-doped gold nanoclusters (AuAgNCs) and on their three-dimensional arrangement in a hybrid system composed of DNA liquid crystals (LCs) and AuAgNCs. UV-vis and fluorescence spectroscopy, transmission electron microscopy (TEM), and multiphoton excitation spectroscopy were used to characterize the nanoparticles. We show that AuAgNCs exhibit two-photon excited luminescence (2PL) emission and second-harmonic generation (SHG) and that these properties remain the same in liquid crystalline matrix. The results are described in detail and discussed in the context of possible imaging application of AuAgNC and specific AuAgNCs organization induced by liquid crystalline ordering of DNA molecules.

Recent advances in biomedical applications of fluorescent gold nanoclusters

Fluorescent gold nanoclusters (AuNCs) are emerging as novel fluorescent materials and have attracted more and more attention in the field of biolabeling, biosensing, bioimaging and targeted cancer treatment because of their unusual physicochemical properties, such as long fluorescence lifetime, ultrasmall size, large Stokes shift, strong photoluminescence, as well as excellent biocompatibility and photostability. Recently, significant efforts have been committed to the preparation, functionalization and biomedical application studies of fluorescent AuNCs. In this review, we have summarized the strategies for preparation and surface functionalization of fluorescent AuNCs in the past several years, and highlighted recent advances in the biomedical applications of the relevant fluorescent AuNCs. Based on these observations, we also give a discussion on the current problems and future developments of the fluorescent AuNCs for biomedical applications.