Luminescent Gold Nanorods To Enhance the Near‐Infrared Emission of a Photosensitizer for Targeted Cancer Imaging and Dual Therapy: Experimental and Theoretical Approach

Near infrared-emitting multimodal nanosystem for in vitro magnetic hyperthermia of hepatocellular carcinoma and dual imaging of in vivo liver fibrosis

Prolonged usage of traditional nanomaterials in the biological field has posed several short- and long-term toxicity issues. Over the past few years, smart nanomaterials (SNs) with controlled physical, chemical, and biological features have been synthesized in an effort to allay these challenges. The current study seeks to develop theranostic SNs based on iron oxide to enable simultaneous magnetic hyperthermia and magnetic resonance imaging (MRI), for chronic liver damage like liver fibrosis which is a major risk factor for hepatocellular carcinoma. To accomplish this, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared, coated with a biocompatible and naturally occurring polysaccharide, alginate. The resultant material, ASPIONs were evaluated in terms of physicochemical, magnetic and biological properties. A hydrodynamic diameter of 40 nm and a transverse proton relaxation rate of 117.84 mM-1 s-1 pronounces the use of ASPIONs as an efficient MRI contrast agent. In the presence of alternating current of 300 A, ASPIONs could elevate the temperature to 45 °C or more, with the possibility of hyperthermia based therapeutic approach. Magnetic therapeutic and imaging potential of ASPIONs were further evaluated respectively in vitro and in vivo in HepG2 carcinoma cells and animal models of liver fibrosis, respectively. Finally, to introduce dual imaging capability along with magnetic properties, ASPIONs were conjugated with near infrared (NIR) dye Atto 700 and evaluated its optical imaging efficiency in animal model of liver fibrosis. Histological analysis further confirmed the liver targeting efficacy of the developed SNs for Magnetic theranostics and optical imaging as well as proved its short-term safety, in vivo.

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.

Inhibition of Pro-Survival Autophagy Induced by Rare-Earth Nanocomposites for Promoting Photothermal Therapy of Visualized Tumors

Manipulation of autophagic processes has emerged as a promising strategy for synergizing nanoagent-mediated photothermal therapy (PTT). Most of the current studies focus on improving PTT efficacy by inhibiting pro-survival autophagy induced by the heat generated from the photothermal process. However, autophagy induced by the nanoagents is usually ignored, which may weaken the effect of autophagy-mediated efficacy improvement in PTT if induced autophagy is pro-death. Therefore, this work aims at developing a nanoagent that is able to induce heat-synergetic pro-survival autophagy to optimize the efficacy of PTT. An approach is developed to coat carbon layer, polyethylenimine (PEI), and folic acid (FA) on NaYF₄ :Er,Yb,Nd@NaNdF₄ (DCNPs@C@PEI@FA, DCPF) nanoparticles successively, giving access to the nanoagent to induce pro-survival autophagy. The synthetic imaging-guided photothermal nanoagent displays outstanding targeting ability and biocompatibility based on the surface modification of PEI and FA. By using an autophagy inhibitor chloroquine, a conspicuously synergistic effect on DCPF-mediated PTT in vitro and in vivo tumor models (HeLa) is achieved. A promising strategy is presented here to enhance the efficacy of imaging-guided PTT by modulating the autophagy induced by the nanoagent.

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.

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.

Asialoglycoprotein receptor targeted optical and magnetic resonance imaging and therapy of liver fibrosis using pullulan stabilized multi-functional iron oxide nanoprobe

Early diagnosis and therapy of liver fibrosis is of utmost importance, especially considering the increased incidence of alcoholic and non-alcoholic liver syndromes. In this work, a systematic study is reported to develop a dual function and biocompatible nanoprobe for liver specific diagnostic and therapeutic applications. A polysaccharide polymer, pullulan stabilized iron oxide nanoparticle (P-SPIONs) enabled high liver specificity via asialogycoprotein receptor mediation. Longitudinal and transverse magnetic relaxation rates of 2.15 and 146.91 mM⁻¹ s⁻¹ respectively and a size of 12 nm, confirmed the T₂ weighted magnetic resonance imaging (MRI) efficacy of P-SPIONs. A current of 400A on 5 mg/ml of P-SPIONs raised the temperature above 50 °C, to facilitate effective hyperthermia. Finally, a NIR dye conjugation facilitated targeted dual imaging in liver fibrosis models, in vivo, with favourable histopathological results and recommends its use in early stage diagnosis using MRI and optical imaging, and subsequent therapy using hyperthermia.

Influence of interface structure in redox and optical properties of thio and seleno-Ureidopeptide functionalized bimetallic gold nanocluster: DFT study

A simple cluster-ligand interaction model is introduced to describe the surface passivation of bimetallic gold clusters by SUP (Thioureidopeptide) and SeUP (Selenoureidopeptide) ligands. The conformational search based on neutral peptide binding modes and their computed interaction energies show the existence of various structural isomers within 10 kcal mol^-1. Further, the negatively charged deprotonated peptide was found to strongly interact with metal cluster through the carboxylate unit. Irrespective of the mode of binding and configuration the metal cluster found to exist in parent geometry in all three charge states. The calculated HOMO-LUMO gap of ligated clusters predicts an increase in chemical stability after the ligation. Moreover, the ligation was found to decrease the energy required for oxidation and reduction. The excited-state calculations indicate absorption maxima at 200-400 nm corresponds to the LMCT transition. In all the hybrid cluster models the donor and acceptor end of the peptide were found to remain intact. However, the charge migration dynamics observed only in the homo-metallic gold-ligand hybrids, owing to the larger charge separation.

Lysosome-Targeted Gold Nanotheranostics for In Situ SERS Monitoring pH and Multimodal Imaging-Guided Phototherapy

The integration of surface-enhanced Raman spectrum (SERS) and fluorescence-photoacoustic multimodal imaging in near-infrared photothermal therapy is highly desirable for cancer theranostic. However, typically, gold nanotheranostics usually require an additional modification of fluorophores and complex design refinements. In this work, by integrating surface-modified cysteine-hydroxyl merocyanine (CyHMC) molecules onto AuNRs, a novel lysosome-targeted gold-based nanotheranostics AuNRs-CyHMC that combines the specificity of Raman spectrum, the speed of fluorescence imaging, and deep penetration of photoacoustic imaging was successfully fabricated. Interestingly, fluorescence and Raman signals in this AuNRs-CyHMC system do not interfere, but it has pH-sensitive Raman signals and self-fluorescence localization ability under different excitation wavelengths. Fluorescence co-localization experiments further confirmed the lysosome-targeting ability of AuNRs-CyHMC. Typically, the proposed nanotheranostics were capable of SERS monitoring pH changes in both phosphate-buffered saline and living cells. Meanwhile, in vitro and in vivo experiments revealed that AuNRs-CyHMC possessed excellent fluorescence-photoacoustic performance and could be used for multimodal imaging-guided photothermal therapy. Furthermore, our work implied that gold nanotheranostics can provide great potential for cancer diagnosis and treatment.

Cytotoxicity and genotoxicity of gold nanorods assisted photothermal therapy against Ehrlich carcinoma in-vivo

AIM

Preparation of pegylated gold nanorods (PEG-AuNRs) that are capable of converting near infrared (NIR) light into heat. Evaluation of cancer therapeutic efficacy and long-term toxicity of the proposed photothermal therapy in comparison with other conventional modalities.

MATERIALS AND METHODS

Prepared PEG-AuNRs were characterized by measuring their absorption spectra, zeta potential, and transmission electron microscope (TEM). Cancer therapeutic efficacy was assessed by monitoring tumor growth, measuring DNA damage and superoxide dismutase (SOD) and malondialdehyde (MDA) levels in addition to examining tumor histopathology. Further analysis concerning the toxicity of all the proposed treatment modalities was also assessed by evaluating the cytotoxicity and genotoxicity in liver and kidney tissues.

KEY FINDINGS

The results demonstrated that both photothermal therapy (PEG-AuNRs + NIR laser) and chemotherapy (cisplatin) have higher efficacy in diminishing Ehrlich tumor growth with significance DNA damage over the other treatment modalities. Concerning the biosafety issue, mice treated photothermally exhibited lower MDA level and higher SOD activity in liver and kidney tissues compared with other treated groups. DNA damage represented by tail moment and olive moment of kidney tissues exhibited lower values for photothermal treated group and higher values for cisplatin treated group.

SIGNIFICANCE

Photothermal therapy (PEG-AuNRs + NIR laser) potentiates higher efficacy in treating Ehrlich tumor with minimum toxicity in comparison with other conventional treatment modalities.