Gold nanorods decorated with a cancer drug for multimodal imaging and therapy

Gold nanorod-based smart platform for efficient cellular uptake and combination therapy

Gold nanorods (GNRs) have received much attention as potential drug-delivery vehicles because of their various advantages such as good biocompatibility, passive targeting, responsiveness to stimuli, and easy post-functionalization by surface modification. However, the drug structure might be changed for loading into GNRs, making it difficult to load various drugs, and the space to contain drugs is small, making it difficult to deliver sufficient drugs required for treatment compared with other porous materials. Herein, we report an amphiphilic polymer-coated GNR platform for chemo- and photothermal combination therapy. Amphiphilic polymers comprise hydrophobic alkyl chains for drug encapsulation, polyethylene glycol for biocompatibility, and folic acid for cancer targeting. GNRs generate heat energy under near-infrared light irradiation, promoting controlled drug release, and inducing cellular uptake by deforming the cell membrane. On-demand release behavior was traced with Nile red, and targeting and delivery efficiency were confirmed with paclitaxel through cellular experiments. This GNR-based platform enables combination therapy with passive and active targeting to enhance the efficacy of cancer treatment.

Bifunctional cysteine gold nanoclusters for β-amyloid fibril inhibition and fluorescence imaging: a distinctive approach to manage Alzheimer's disease

Alzheimer's disease (AD) is a progressive complex neurodegenerative disorder affecting millions of individuals worldwide. Currently, there is no effective treatment for AD. AD is characterized by the deposition of amyloid plaques/fibrils. One major strategy for managing this disease is by slowing the progression of AD using different drugs which could potentially limit free-radical formation, oxidative stress and lipid peroxidation and promote the survival of neurons exposed to β-amyloid. Inhibition of amyloid fibrillization and clearance of amyloid plaques/fibrils are essential for the prevention and treatment of AD. The thiophilic interaction between the side chain of an aromatic residue in a polypeptide and a sulphur atom of the compound can effectively inhibit amyloid fibril formation. In this work, we have synthesized cysteine-capped gold nanoclusters (Cy-AuNCs) which exhibit inherent red emission and can disintegrate amyloid fibrils through the aforementioned thiophilic interactions. Herein, we also used molecular docking to study the thiophilic interactions between the sulphur atom of Cy-AuNCs and the aromatic rings of the protein. Finally, the gold cluster was functionalized with a brain targeting molecule, Levodopa (AuCs-LD), to specifically target the brain and to facilitate passage through the blood brain barrier (BBB). Both Cy-AuNCs and AuCs-LD showed good biocompatibility and the inherent fluorescence properties of nanoclusters enabled real time imaging. The efficacy of the nanoclusters to disintegrate amyloid fibrils and their ability to cross the BBB were demonstrated both in vitro and in vivo in the BBB model and the AD animal model respectively. Our results imply that nanoparticle-based artificial molecular chaperones may offer a promising therapeutic approach for AD.

Gold nanorods assisted photothermal therapy of bladder cancer in mice: A computational study on the effects of gold nanorods distribution at the centre, periphery, and surface of bladder cancer

BACKGROUND AND OBJECTIVES

Gold nanorod-assisted photothermal therapy (GNR-PTT) is a cancer treatment whereby GNRs incorporated into the tumour act as photo-absorbers to elevate the thermal destruction effect. In the case of bladder, there are few possible routes to target the tumour with GNRs, namely peri/intra-tumoural injection and intravesical instillation of GNRs. These two approaches lead to different GNR distribution inside the tumour and can affect the treatment outcome.

METHODOLOGY

The present study investigates the effects of heterogeneous GNR distribution in a typical setup of GNR-PTT. Three cases were considered. Case 1 considered the GNRs at the tumour centre, while Case 2 represents a hypothetical scenario where GNRs are distributed at the tumour periphery; these two cases represent intratumoural accumulation with different degree of GNR spread inside the tumour. Case 3 is achieved when GNRs target the exposed tumoural surface that is invading the bladder wall, when they are delivered by intravesical instillation.

RESULTS

Results indicate that for a laser power of 0.6 W and GNR volume fraction of 0.01%, Case 2 and 3 were successful in achieving complete tumour eradication after 330 and 470 s of laser irradiation, respectively. Case 1 failed to form complete tumour damage when the GNRs are concentrated at the tumour centre but managed to produce complete tumour damage if the spread of GNRs is wider. Results from Case 2 also demonstrated a different heating profile from Case 1, suggesting that thermal ablation during GNR-PTT is dependant on the GNRs distribution inside the tumour. Case 3 shows similar results to Case 2 whereby gradual but uniform heating is observed. Cases 2 and 3 show that uniformly heating the tumour can reduce damage to the surrounding tissues.

CONCLUSIONS

Different GNR distribution associated with the different methods of introducing GNRs to the bladder during GNR-PTT affect the treatment outcome of bladder cancer in mice. Insufficient spreading during intratumoural injection of GNRs can render the treatment ineffective, while administered via intravesical instillation. GNR distribution achieved through intravesical instillation present some advantages over intratumoural injection and is worthy of further exploration.

Biology of cancer; from cellular and molecular mechanisms to developmental processes and adaptation

Cancer research has been largely focused on the cellular and molecular levels of investigation. Recent data show that not only the cell but also the extracellular matrix plays a major role in the progression of malignancy. In this way, the cells and the extracellular matrix create a specific local microenvironment that supports malignant development. At the same time, cancer implies a systemic evolution which is closely related to developmental processes and adaptation. Consequently, there is currently a real gap between the local investigation of cancer at the microenvironmental level, and the pathophysiological approach to cancer as a systemic disease. In fact, the cells and the matrix are not only complementary structures but also interdependent components that act synergistically. Such relationships lead to cell-matrix integration, a supracellular form of biological organization that supports tissue development. The emergence of this supracellular level of organization, as a structure, leads to the emergence of the supracellular control of proliferation, as a supracellular function. In humans, proliferation is generally involved in developmental processes and adaptation. These processes suppose a specific configuration at the systemic level, which generates high-order guidance for local supracellular control of proliferation. In conclusion, the supracellular control of proliferation act as an interface between the downstream level of cell division and differentiation, and upstream level of developmental processes and adaptation. Understanding these processes and their disorders is useful not only to complete the big picture of malignancy as a systemic disease, but also to open new treatment perspectives in the form of etiopathogenic (supracellular or informational) therapies.

A nanoarchitecture of a gold cluster conjugated gold nanorod hybrid system and its application in fluorescence imaging and plasmonic photothermal therapy

Engineering different nanomaterials into a single functional material can impart unique properties of the parental nanoparticles, especially in the field of bio imaging and therapy. Gold nanomaterials having different sizes, shapes and dimensionalities exhibit exceptional properties apart from their non-toxicity and hence are strong candidates in the biomedical field. Designing a hybrid nanomaterial of two gold nanostructures retaining the individual properties of the parental nanomaterials is challenging. Here, we demonstrate the synthesis of a hybrid nanomaterial (GQC@GNR), comprising an extremely small gold nanocluster and a representative of the asymmetric gold nanostructure, i.e., a gold nanorod, both having their own different exclusive optical properties like tuneable emission and NIR absorption characteristics, respectively. The hybrid system is designed to retain its emission and absorption in the NIR region to use it as an agent for simultaneous imaging and therapy. The formation of GQC@GNR and its architectonics heavily depend on the synthesis route and the parameters adopted which in turn have a direct influence on its properties. The architecture and its connection to the optical properties are explained using UV-Vis absorption and photoluminescence spectroscopy, zeta potential, transmission electron microscopy, etc. DFT-based computational modelling supports architectonics as explained by the experimental findings. The formation of the gold-gold hybrid system witnessed interesting science with a strong indication that materials with desired properties can be designed by appropriately modulating the architectonics of hybrid formation. Finally, folate conjugated GQC@GNR demonstrated its efficacy for targeted imaging and photothermal therapy in HeLa cells and tumor-bearing animal models. The detailed therapeutic efficacy of GQC@GNR is also explained based on Raman spectroscopy.

Copper Nanocluster Enabled Simultaneous Photodynamic and Chemo Therapy for Effective Cancer Diagnosis and Treatment In Vitro

Metal nanocluster mediated cancer diagnosis and therapy have drawn considerable attention in recent years due to its unique optical and photophysical properties. Such kind of material is highly useful for diagnosis, treatment, and further follow-up of the disease. However, a single treatment modality is not sufficient for the complete cure of the same. Multiple therapeutic strategies are one of the most promising methods for effective treatment along with an early-stage diagnosis. To address the multiple therapeutic modalities in a single nanomaterial, a copper nanocluster is synthesized using glutathione having inherent singlet oxygen generation and emission at 674 nm. A tumor-targeting agent (folic acid) and an anti-cancer drug (doxorubicin) is conjugated to the copper cluster for cancer diagnosis via targeted imaging and further double therapy (photodynamic and chemotherapy) in vitro . 10.5 µg (18.1 nmoles) of drug conjugated copper cluster shows 56% cell death for a 30 s laser irradiation in Hela cells. Effective cancer cell imaging and therapeutic efficacy are demonstrated in vitro .

NIR-II-responsive AuNRs@SiO2-RB@MnO2 nanotheranostic for multimodal imaging-guided CDT/PTT synergistic cancer therapy

Specific tumor-responsive capabilities and efficient synergistic therapeutic performance are the keys to effective tumor treatment. Herein, AuNRs@SiO₂-RB@MnO₂ was developed as a new type of tumor-responsive nanotheranostic for multimodal imaging and synergistic chemodynamic/photothermal therapy. In AuNRs@SiO₂-RB@MnO₂, the SiO₂ layer wraps the AuNRs, providing light absorption in the second near-infrared (NIR-II) region. The SiO₂ layer also adsorbs the MnO₂ nanosheets, which have Fenton-like activity, resulting in a fluorescent sensing platform based on the fluorescence quenching properties of MnO₂ for rhodamine B dye. The fluorescence can be recovered by the consumption of MnO₂ by glutathione, which simultaneously produces Mn²⁺ in the tumor region. The recovery of fluorescence reflects the consumption of glutathione and the increase in Mn²⁺, which produces hydroxyl radicals via Fenton-like reaction in the tumor microenvironment to realize chemodynamic therapy. Meanwhile, the AuNRs are a good photothermal reagent that can effectively absorb NIR-II light and convert it into heat energy to kill tumor cells via photothermal therapy. The NIR-II absorption performance of the AuNRs provides good photoacoustic imaging and deep photothermal performance, which is favorable for efficient NIR-II photoacoustic imaging-guided photothermal therapy. As a result, the AuNRs@SiO₂-RB@MnO₂ nanotheranostic exhibits outstanding imaging and synergistic chemodynamic/photothermal therapeutic performance for tumor imaging and treatment.

Fluorescent-based nanosensors for selective detection of a wide range of biological macromolecules: A comprehensive review

Thanks to their unique attributes, such as good sensitivity, selectivity, high surface-to-volume ratio, and versatile optical and electronic properties, fluorescent-based bioprobes have been used to create highly sensitive nanobiosensors to detect various biological and chemical agents. These sensors are superior to other analytical instrumentation techniques like gas chromatography, high-performance liquid chromatography, and capillary electrophoresis for being biodegradable, eco-friendly, and more economical, operational, and cost-effective. Moreover, several reports have also highlighted their application in the early detection of biomarkers associated with drug-induced organ damage such as liver, kidney, or lungs. In the present work, we comprehensively overviewed the electrochemical sensors that employ nanomaterials (nanoparticles/colloids or quantum dots, carbon dots, or nanoscaled metal-organic frameworks, etc.) to detect a variety of biological macromolecules based on fluorescent emission spectra. In addition, the most important mechanisms and methods to sense amino acids, protein, peptides, enzymes, carbohydrates, neurotransmitters, nucleic acids, vitamins, ions, metals, and electrolytes, blood gases, drugs (i.e., anti-inflammatory agents and antibiotics), toxins, alkaloids, antioxidants, cancer biomarkers, urinary metabolites (i.e., urea, uric acid, and creatinine), and pathogenic microorganisms were outlined and compared in terms of their selectivity and sensitivity. Altogether, the small dimensions and capability of these nanosensors for sensitive, label-free, real-time sensing of chemical, biological, and pharmaceutical agents could be used in array-based screening and in-vitro or in-vivo diagnostics. Although fluorescent nanoprobes are widely applied in determining biological macromolecules, unfortunately, they present many challenges and limitations. Efforts must be made to minimize such limitations in utilizing such nanobiosensors with an emphasis on their commercial developments. We believe that the current review can foster the wider incorporation of nanomedicine and will be of particular interest to researchers working on fluorescence technology, material chemistry, coordination polymers, and related research areas.

Mitochondrial-induced Epigenetic Modifications: From Biology to Clinical Translation

Mitochondria are maternally inherited semi-autonomous organelles that play a central role in redox balance, energy metabolism, control of integrated stress responses, and cellular homeostasis. The molecular communication between mitochondria and the nucleus is intricate and bidirectional in nature. Though mitochondrial genome encodes for several key proteins involved in oxidative phosphorylation, several regulatory factors encoded by nuclear DNA are prominent contributors to mitochondrial biogenesis and function. The loss of synergy between this reciprocal control of anterograde (nuclear to mitochondrial) and retrograde (mitochondrial to nuclear) signaling, triggers epigenomic imbalance and affects mitochondrial function and global gene expressions. Recent expansions of our knowledge on mitochondrial epigenomics have offered novel perspectives for the study of several non-communicable diseases including cancer. As mitochondria are considered beacons for pharmacological interventions, new frontiers in targeted delivery approaches could provide opportunities for effective disease management and cure through reversible epigenetic reprogramming. This review focuses on recent progress in the area of mitochondrial-nuclear cross-talk and epigenetic regulation of mitochondrial DNA methylation, mitochondrial micro RNAs, and post-translational modification of mitochondrial nucleoid-associated proteins that hold major opportunities for targeted drug delivery and clinical translation.

Improvement of Gold Nanorods in Photothermal Therapy: Recent Progress and Perspective

Cancer is a life-threatening disease, and there is a significant need for novel technologies to treat cancer with an effective outcome and low toxicity. Photothermal therapy (PTT) is a noninvasive therapeutic tool that transports nanomaterials into tumors, absorbing light energy and converting it into heat, thus killing tumor cells. Gold nanorods (GNRs) have attracted widespread attention in recent years due to their unique optical and electronic properties and potential applications in biological imaging, molecular detection, and drug delivery, especially in the PTT of cancer and other diseases. This review summarizes the recent progress in the synthesis methods and surface functionalization of GNRs for PTT. The current major synthetic methods of GNRs and recently improved measures to reduce toxicity, increase yield, and control particle size and shape are first introduced, followed by various surface functionalization approaches to construct a controlled drug release system, increase cell uptake, and improve pharmacokinetics and tumor-targeting effect, thus enhancing the photothermal effect of killing the tumor. Finally, a brief outlook for the future development of GNRs modification and functionalization in PTT is proposed.

Hairpin Oligonucleotide Can Functionalize Gold Nanorods for in Vivo Application Delivering Cytotoxic Nucleotides and Curcumin: A Comprehensive Study in Combination with Near-Infrared Laser

We prepared a multimodality nanocomplex by functionalizing gold nanorods (GNRs) with a cytotoxic nucleoside, 5-fluoro-2'-deoxyuridine (FdU) containing a DNA hairpin, along with complexation of pleiotropic molecule curcumin. Conjugates were investigated for anti-tumor activity using an Ehrlich carcinoma model in combination with 808 nm laser irradiation. We demonstrated that hairpin-functionalized GNRs are suitable for intravenous administration, including delivery of cytotoxic nucleotides and curcumin. Curcumin binding with FdU-hairpin-functionalized GNRs displayed improved anti-tumor activity in part by inducing a lymphocyte-mediated immune response. The complex showed notable photothermal activity in vitro; however, 808 nm laser irradiation of the tumor following treatment with the complex did not increase the anti-tumor effect significantly. Biodistribution studies depicted that the nanoconjugates localized primarily in the sinusoidal structures of the liver and spleen with minimal tumor accumulation. Curcumin complexation alleviated the reduction in the RBC count that was observed for the conjugate without curcumin, especially in combination with laser irradiation. Localization of FdU-hairpin-GNR conjugates in the liver and spleen evoked an inflammatory response, which was mitigated by curcumin complexation. However, no functional abnormality was found in the liver in any case. Curcumin binding also notably decreased nanoconjugate accumulation in lungs and significantly reduced inflammation. Biodistribution studies were consistent with previous reports, suggesting that optimization of the GNR size and surface coating is required for more efficient tumor localization via the enhanced permeability and retention (EPR) effect. Our studies demonstrate that DNA/RNA hairpins are suitable for GNR surface functionalization and enable delivery of cytotoxic nucleotides as well as curcumin in vivo with potential for synergistic anti-cancer therapy.

Recent advances in applications of nanoparticles in SERS in vivo imaging

Surface-enhanced Raman scattering (SERS) technique has been regarded as one of the most important research methods in the field of single-molecule science. Since the previous decade, the application of nanoparticles for in vivo SERS imaging becomes the focus of research. To enhance the performance of SERS imaging, researchers have developed several SERS nanotags such as gold nanostars, copper-based nanomaterials, semiconducting quantum dots, and so on. The development of Raman equipment is also necessary owing to the current limitations. This review describes the recent advances of SERS nanoparticles and their applications for in vivo imaging in detail. Specific examples highlighting the in vivo cancer imaging and treatment application of SERS nanoparticles. A perspective on the challenges and opportunities of nanoparticles in SERS in vivo imaging is also provided. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Gold nanowire growth through stacking fault mechanism by oleylamine-mediated synthesis

Tadpole-like gold nanowires were obtained by the oleylamine-mediated synthesis presenting an unusual mixture of fcc and hcp phases. Structural analyses were performed to understand their structure and growth using aberration-corrected high-resolution scanning transmission electron microscopy and electron diffraction at the tail region of tadpoles showing that the anisotropic shape occurred due to stacking fault defects. Stacking faults and twin defects are responsible for the hcp phase inferring a defect dependent growth. The stacking fault model used in X-ray diffraction (XRD) refinement resulted in 60% of hcp stacking sequences. Temperature-dependent XRD analyses showed that the faults become unstable around 120 °C, and it is completely converted to the fcc phase at 230 °C. We attribute the nanowire formation to a stacking fault mechanism of growth that begins in the later stage of nanoparticle growth. The UV-Vis spectrum presented two localized surface plasmon resonance bands at 500 nm and from 800 nm extending to near-infrared, associated with transverse and longitudinal modes, respectively. A surprising ferromagnetic behavior is also observed with a blocking temperature near 300 K.

A dual signal on-off fluorescent nanosensor for the simultaneous detection of copper and creatinine

The transition of conventional medicine to personalized medicine has paved the way for sensing new biomolecules. Consequently, this field attracted wide interest due to its capability to provide information on point of care basis. Multi-analyte sensors that emerged recently can perform quick and affordable analysis with minimum quantity of blood samples compared to traditional sensing of individual analytes. The present study focuses on the development of a quantum dot (Qd) based nanosensor for the simultaneous detection of copper and creatinine; two biologically relevant molecules. The sensor was designed by forming a complex of Qd with 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and picric acid through carboxylic bond formation of Qd-EDC with picric acid. The dual independent emissions of the Qd-EDC complex was used for the simultaneous detection of creatinine and copper by a turn on/turn off method and was successfully demonstrated with a sensitivity of nanomolar to millimolar, and micromolar to millimolar range respectively. The multianalyte sensor thus developed has quick response and works well under normal conditions of temperature and pH. It is also shown to work in cellular environment and blood serum. A simple image based detection of creatinine using the sensor strips has also been attempted by means of a mobile camera and validated with human blood samples.

Polypyrrole-based double rare earth hybrid nanoparticles for multimodal imaging and photothermal therapy

A polypyrrole-based theranostic agent containing double rare-earth elements was constructed and demonstrated promising application for T₁/T₂-weighted MRI/CT tri-modal imaging guided photothermal cancer therapy.

Gold nanoparticles in chemo-, immuno-, and combined therapy: review [Invited]

Functionalized gold nanoparticles (GNPs) with controlled geometrical and optical properties have been the subject of intense research and biomedical applications. This review summarizes recent data and topical problems in nanomedicine that are related to the use of variously sized, shaped, and structured GNPs. We focus on three topical fields in current nanomedicine: (1) use of GNP-based nanoplatforms for the targeted delivery of anticancer and antimicrobial drugs and of genes; (2) GNP-based cancer immunotherapy; and (3) combined chemo-, immuno-, and phototherapy. We present a summary of the available literature data and a short discussion of future work.

Chemical Transformation of Nanorods to Nanowires: Reversible Growth and Dissolution of Anisotropic Gold Nanostructures

This manuscript describes a reversible wet chemical process for the tip-selective one-dimensional (1D) growth and dissolution of gold nanorods (AuNRs) and gold nanowires (AuNWs). Tip-selective dissolution was achieved by oxidation of AuNRs with a Au(III)/CTAB complex, whereas the growth of AuNRs was carried out by the reduction of Au(I) ions on the AuNR surface with a mild reducing agent, ascorbic acid (AA). Both the dissolution and growth processes are highly tip selective and proceed exclusively in one dimension. A decrease in the aspect ratio (AR) of AuNRs during the dissolution resulted in a blue shift in the longitudinal plasmon band (LPB) position, and red shifts in the LPB position were achieved by increasing the AR by 1D growth of AuNRs. Both growth and dissolution processes are fully controllable and can be stopped and resumed at any given time when the desired AR and/or LPB position is achieved. In addition, the tip-selective 1D growth of AuNRs can be continued with the additional supply of Au(I)/CTAB/AA solution to produce extremely long AuNWs.

Identification of key genes and specific pathways potentially involved in androgen-independent, mitoxantrone-resistant prostate cancer

Background

Resistance to mitoxantrone (MTX), an anthracenedione antineoplastic agent used in advanced and metastatic androgen-refractory prostate cancer (PCa), seriously limits therapeutic success.

Methods

Xenografts from two human PCa cell lines (VCaP and CWR22) were established in male severe combined immunodeficiency mice, and MTX was administered, with or without concurrent castration, three times a week until tumors relapsed. Microarray technology was used to screen for differentially expressed genes (DEGs) in androgen-independent, MTX-resistant PCa xenografts. Gene expression profiles of MTX-treatment xenografts and their respective parental cell lines were performed using an Agilent whole human genome oligonucleotide microarray and analyzed using Ingenuity Pathway Analysis software.

Results

A total of 636 genes were differentially expressed (fold change ≥1.5; P<0.05) in MTX-resistant castration-resistant prostate cancer (CRPC) xenografts. Of these, 18 were selected to be validated and showed that most of these genes exhibited a transcriptional profile similar to that seen in the microarray (Pearson’s r=0.87). Western blotting conducted with a subset of genes deregulated in MTX-resistant CRPC tumors was shown through network analysis to be involved in androgen synthesis, drug efflux, ATP synthesis, and vascularization.

Conclusion

The present data provide insight into the genetic alterations underlying MTX resistance in androgen-independent PCa and highlight potential targets to improve therapeutic outcomes.

Real Time Imaging and Dynamics of Hippocampal Zn2+ under Epileptic Condition Using a Ratiometric Fluorescent Probe

Zinc, the essential trace element in human body exists either in the bound or free state, for both structural and functional roles. Insights on Zn2+ distribution and its dynamics are essential in view of the fact that Zn2+ dyshomeostasis is a risk factor for epileptic seizures, Alzheimer's disease, depression, etc. Herein, a bipyridine bridged bispyrrole (BP) probe is used for ratiometric imaging and quantification of Zn2+ in hippocampal slices. The green fluorescence emission of BP shifts towards red in the presence of Zn2+. The probe is used to detect and quantify the exogenous and endogenous Zn2+ in glioma cells and hippocampal slices. The dynamics of chelatable zinc ions during epileptic condition is studied in the hippocampal neurons, in vitro wherein the translocation of Zn2+ from presynaptic to postsynaptic neuronal bodies is imaged and ratiometrically quantified. Raman mapping technique is used to confirm the dynamics of Zn2+ under epileptic condition. Finally, the Zn2+ distribution was imaged in vivo in epileptic rats and the total Zn2+ in rat brain was quantified. The results favour the use of BP as an excellent Zn2+ imaging probe in biological system to understand the zinc associated diseases and their management.

Dual-functional peptide conjugated gold nanorods for the detection and photothermal ablation of pathogenic bacteria

Au@peptide937 nanorods for detecting bacteria by specific binding and killing bacteria due to the local hyperthermal effect.