Rattle-Type Gold Nanorods/Porous-SiO2 Nanocomposites as Near-Infrared Light-Activated Drug Delivery Systems for Cancer Combined Chemo–Photothermal Therapy

Reversal of doxorubicin-resistance of MCF-7/Adr cells via multiple regulations by glucose oxidase loaded AuNRs@MnO2@SiO2 nanocarriers

Targeting to multiple MDR mechanisms is a desired strategy for efficient reversal of multidrug resistance (MDR). Herein, a multi-functional and hierarchical-structured AuNRs@MnO2@SiO2 (AMS) nanocarrier is reported for multiple regulations of MDR. The glucose oxidase (GOx) loaded AMS (AMS/G) showed efficient capabilities of hypoxia-relieving, O2-generation enhanced cancer starvation therapy (CST), and near-infrared (NIR) laser photothermal therapy (PTT) to MCF-7/Adr, a doxorubicin (Dox)-resistant breast cancer cell line. It was revealed that hypoxia inducible factor-1α and heat shock protein 90, can be significantly down-regulated by AMS/G. The Dox resistance and the adenosine triphosphate (ATP)-binding cassette (ABC) transporters: P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and breast cancer resistance protein (BCRP), can be dramatically reversed by the AMS/G+NIR treatment. Specifically, the hypoxia-relieving function can down-regulate all the three ABC transporters. The enhanced CST decreases the expression of MRP1. The PTT diminishes the BCRP and MRP1. Assisted by the multiple and synergistic reversal mechanisms, the Dox co-loaded AMS/G (AMS/D/G) with NIR laser significantly inhibited the cell proliferation, migration, and drug efflux at both normoxia and hypoxia conditions. Cell apoptosis is greatly induced in a caspase-3 dependent manner. Tumor ATP depletion and Dox accumulation were confirmed in vivo. The tumor growth inhibition is greatly and synergistically enhanced, without inducing obvious side effects. Collectively, the nanostructured AMS/D/G can inhibit multiple ABC transporters and provide a promisingly platform for highly efficient reversal of tumor drug resistance.

Evolution of nMOFs in photodynamic therapy: from porphyrins to chlorins and bacteriochlorins for better efficacy

Photodynamic therapy (PDT) has gained significant attention due to its non-invasive nature, low cost, and ease of operation. Nanoscale metal-organic frameworks (nMOFs) incorporating porphyrins, chlorins, and bacteriochlorins have emerged as one of the most prominent photoactive materials for tumor PDT. These nMOFs could enhance the water solubility, stability and loading efficiency of photosensitizers (PSs). Their highly ordered porous structure facilitates O2 diffusion and enhances the generation of 1O2 from hydrophobic porphyrins, chlorins, and bacteriochlorins, thereby improving their efficacy of phototherapy. This review provides insights into the PDT effects of nMOFs derived from porphyrins, chlorins, and bacteriochlorins. It overviews the design strategies, types of reactive oxygen species (ROS), ROS generation efficiency, and the unique biological processes involved in inhibiting tumor cell proliferation, focusing on the mechanism by which molecular structure leads to enhanced photochemical properties. Finally, the review highlights the new possibilities offered by porphyrins, chlorins, and bacteriochlorins-based nMOFs for tumor PDT, emphasizing how optimized design can further improve the bioapplication of porphyrin derivatives represented PSs. With ongoing research and technological advancements, we anticipate that this review will garner increased attention from scientific researchers toward porphyrin-based nMOFs, thereby elevating their potential as a prominent approach in the treatment of malignant tumors.

Wash-free fluorescent tools based on organic molecules: Design principles and biomedical applications

Fluorescence-assisted tools based on organic molecules have been extensively applied to interrogate complex biological processes in a non-invasive manner with good sensitivity, high resolution, and rich contrast. However, the signal-to-noise ratio is an essential factor to be reckoned with during collecting images for high fidelity. In view of this, the wash-free strategy is proven as a promising and important approach to improve the signal-to-noise ratio, thus a thorough introduction is presented in the current review about wash-free fluorescent tools based on organic molecules. Firstly, generalization and summarization of the principles for designing wash-free molecular fluorescent tools (WFTs) are made. Subsequently, to make the thought of molecule design more legible, a wash-free strategy is highlighted in recent studies from four diverse but tightly binding aspects: (1) special chemical structures, (2) molecular interactions, (3) bio-orthogonal reactions, (4) abiotic reactions. Meanwhile, biomedical applications including bioimaging, biodetection, and therapy, are ready to be accompanied by. Finally, the prospects for WFTs are elaborated and discussed. This review is a timely conclusion about wash-free strategy in the fluorescence-guided biomedical applications, which may bring WFTs to the forefront and accelerate their extensive applications in biology and medicine.

Recent Advances in Porphyrin-Based Covalent Organic Frameworks for Synergistic Photodynamic and Photothermal Therapy

Porphyrin's excellent biocompatibility and modifiability make it a widely studied photoactive material. However, its large π-bond conjugated structure leads to aggregation and precipitation in physiological solutions, limiting the biomedical applications of porphyrin-based photoactive materials. It has been demonstrated through research that fabricating porphyrin molecules into nanoscale covalent organic frameworks (COFs) structures can circumvent issues such as poor dispersibility resulting from hydrophobicity, thereby significantly augmenting the photoactivity of porphyrin materials. Porphyrin-based COF materials can exert combined photodynamic and photothermal effects, circumventing the limitations of photodynamic therapy (PDT) due to hypoxia and issues in photothermal therapy (PTT) from heat shock proteins or the adverse impact of excessive heat on the protein activity of normal tissue. Furthermore, the porous structure of porphyrin COFs facilitates the circulation of oxygen molecules and reactive oxygen species and promotes sufficient contact with the lesion site for therapeutic functions. This review covers recent progress regarding porphyrin-based COFs in treating malignant tumors and venous thrombosis and for antibacterial and anti-inflammatory uses via combined PDT and PTT. By summarizing relevant design strategies, ranging from molecular design to functional application, this review provides a reference basis for the enhanced phototherapy application of porphyrin-based COFs as photoactive materials. This review aims to offer valuable insights for more effective biomedical applications of porphyrin-based COFs through the synthesis of existing experimental data, thereby paving the way for their future preclinical utilization.

Recent advances in cell membrane-coated porphyrin-based nanoscale MOFs for enhanced photodynamic therapy

Porphyrins-based nanoscale metal-organic frameworks (nMOFs) has been widely utilized to kills tumor cells by generating cytotoxic reactive oxygen species (ROS). However, porphyrin based nMOFs (por-nMOFs) still face challenges such as rapid immune clearance and weak tumor targeting. Researchers have discovered that using a top-down biomimetic strategy, where nMOFs are coated with cell membranes, can promote long blood circulation, evade the reticuloendothelial system, and improve cancer cell targeting, thereby significantly enhancing the photodynamic therapy (PDT) effect of nMOFs. This review summarizes the recent work on different cell membranes-coated por-nMOFs for enhanced tumor PDT. This review details the changes in physicochemical properties, enhanced homotypic cancer cell-selective endocytosis, improved tumor tissue targeting, and increased cytotoxicity and effective in vivo tumor suppression after the nMOFs are wrapped with cell membranes. Additionally, this review compares the biological functions of various types of cell membranes, including cancer cell membranes, red blood cell membranes, aptamer-modified red blood cell membranes, and hybrid membranes from the fusion of cancer and immune cells. The review highlights the enhanced immunogenic cell death function when using hybrid membranes derived from the fusion of cancer and immune cell membranes. By summarizing the augmented PDT effects and the combined antitumor outcomes with other therapeutic modalities, this review aims to provide new insights into the biomedical applications of por-nMOFs and offer more references for the preclinical application of porphyrin-based photosensitizers.

Recent progress of porphyrin metal-organic frameworks for combined photodynamic therapy and hypoxia-activated chemotherapy

Nanoscale metal-organic frameworks integrated with porphyrins (Por-nMOFs) have emerged as efficient nanoplatforms for photodynamic therapy (PDT), which relies on the conversion of molecular oxygen into cytotoxic singlet oxygen. However, the hypoxic microenvironment within tumors significantly limits the efficacy of PDT. To address this challenge, researchers have explored various strategies to either alter or exploit the hypoxic conditions in tumors. One such strategy involves leveraging the porous structure of Por-nMOFs to load hypoxia-activated prodrugs (HAPs) like tirapazamine (TPZ), thereby utilizing the tumor's intrinsic hypoxic environment to trigger a chemotherapeutic effect that synergizes with PDT. Advances in nanoscience have enabled the development of porphyrin-based nMOFs capable of simultaneously loading both porphyrin photosensitizers and TPZ, ensuring effective release within cancer cells under high-phosphate conditions. The subsequent activation of co-loaded TPZ, by the tumor's own hypoxic microenvironment, and that created during PDT, facilitates a combined PDT and chemotherapy approach. This method not only enhances the suppression of cancer cell proliferation but also improves control over tumor metastasis while mitigating the negative impact of hypoxia on singular Por-nMOFs in PDT. This review summarizes recent advances in Por-nMOFs research, focusing on the design strategies for enhancing water dispersibility, circulatory stability, and targeting specificity through post-synthetic modifications. Additionally, this review highlights the bioapplication of Por-nMOFs by integrating TPZ chemotherapy and other therapeutic modalities to combat hypoxic and metastatic malignancies. We anticipate that this review will inspire further research into Por-nMOFs and advance their application in biomedicine.

Photothermally enhanced antibacterial wound healing using albumin-loaded tanshinone IIA and IR780 nanoparticles

Chronic and infected wounds, particularly those caused by bacterial infections, present significant challenges in medical treatment. This study aimed to develop a novel nanoparticle formulation to enhance wound healing by combining antimicrobial and photothermal therapy using albumin as a carrier for Tanshinone IIA and the near-infrared photothermal agent IR780. The nanoparticles were synthesized to exploit the antimicrobial effects of Tanshinone IIA and the photothermal properties of IR780 when exposed to near-infrared laser irradiation. Characterization of the nanoparticles was performed using Transmission Electron Microscopy (TEM) and spectroscopic analysis to confirm their successful synthesis. In vitro antibacterial activity was evaluated using cultures of methicillin-resistant Staphylococcus aureus (MRSA), and in vivo efficacy was tested in a mouse model of MRSA-infected wounds. Wound healing progression was assessed over 16 days, with statistical analysis performed using two-way ANOVA followed by Tukey's post-hoc test. The nanoparticles demonstrated significant photothermal properties, enhancing bacterial eradication and promoting the controlled release of Tanshinone IIA. In vitro studies showed superior antibacterial activity, especially under photothermal activation, leading to a substantial reduction in bacterial viability in MRSA cultures. In vivo, nanoparticle treatment combined with near-infrared laser irradiation significantly improved wound closure rates compared to controls and treatments without photothermal activation. By the 16th day post-treatment, significant improvements in wound healing were observed, highlighting the potential of the combined photothermal and pharmacological approach. These findings suggest that albumin-loaded nanoparticles containing Tanshinone IIA and IR780, activated by near-infrared light, could offer an effective therapeutic strategy for managing chronic and infected wounds, promoting both infection control and tissue repair.

Ferrocene-Conjugated Paclitaxel Prodrug for Combined Chemo-Ferroptosis Therapy of Cancer

Herein, we developed a paclitaxel prodrug (PSFc) through the conjugation of paclitaxel (PTX) and ferrocene via a redox-responsive disulfide bond. PSFc displays acid-enhanced catalytic activity of Fenton reaction and is capable of forming stable nanoparticles (PSFc NPs) through the assembly with distearoyl phosphoethanolamine-PEG2000. After being endocytosed, PSFc NPs could release PTX to promote cell apoptosis in response to overexpressed redox-active species of tumor cells. Meanwhile, the ferrocene-mediated Fenton reaction promotes intracellular accumulation of hydroxyl radicals and depletion of glutathione, thus leading to ferroptosis. Compared with the clinically used Taxol, PSFc NPs exhibited more potent in vivo antitumor outcomes through the combined effect of chemotherapy and ferroptosis. This study may offer insight into a facile design of a prodrug integrating different tumor treatment methods for combating malignant tumors.

Epigallocatechin-3-gallate adsorbed on core-shell gold nanorod@mesoporous silica nanoparticles, an antioxidant nanomaterial with photothermal properties

Epigallocatechin-3-gallate (EGCG) exhibits several pharmacological activities with potential benefits for human health, however, it has low oral bioavailability. A promising approach is to transport EGCG in a nanostructured system to protect it until it reaches the site of action and also allow combining chemotherapy with phototherapy to improve its therapeutic efficiency. The aim of this work was to synthesize GNR@mSiO2-NH2/EGCG and characterize the adsorption process, its antioxidant activity, properties and photothermal stability, for its potential use in chemo-photothermal therapy. The nanosystem presented good encapsulation efficiency (19.2 %) and EGCG loading capacity (6.0 %). The DPPH• free radical scavenging capacity (RSA) and chelating activity of the nanosystem was 60.7 ± 6.9 % and 71.0 ± 6.4 % at an EGCG equivalent concentration of 1 µg/mL and 30 µg/mL, respectively. The core-shell NPs presented a good photothermal transduction efficiency of 17 %. EGCG free, as well as its RSA and chelating activity, remained stable after NIR irradiation (808 nm, 7 W/cm2). The morphology of GNR@mSiO2 remained intact after being irradiated with NIR, however, ultrasmall gold NPs could be observed, probably a product of photocracking of GNR. In summary, the nanosystem has good antioxidant activity, photothermal stability, and photothermal transduction ability making it potentially useful for chemo-photothermal therapy.

Combined Photothermal Therapy and Cancer Immunotherapy by Immunogenic Hollow Mesoporous Silicon-Shelled Gold Nanorods

Hyperthermia can be integrated with tumor-killing chemotherapy, radiotherapy and immunotherapy to give rise to an anti-tumor response. To this end, a nano-delivery system is built, which can connect hyperthermia and immunotherapy. On this basis, the impact of such a combination on the immune function of dendritic cells (DCs) is explored. The core of this system is the photothermal material gold nanorod (GNR), and its surface is covered with a silica shell. Additionally, it also forms a hollow mesoporous structure using the thermal etching approach, followed by modification of targeted molecule folic acid (FA) on its surface, and eventually forms a hollow mesoporous silica gold nanorod (GNR@void@mSiO2) modified by FA. GNR@void@mSiO2-PEG-FA (GVS-FA) performs well in photothermal properties, drug carriage and release and tumor targeting performance. Furthermore, the thermotherapy of tumor cells through in vitro NIR irradiation can directly kill tumor cells by inhibiting proliferation and inducing apoptosis. GVS-FA loaded with imiquimod (R837) can be used as a adjuvant to enhance the immune function of DCs through hyperthermia.

Two-Dimensional Copper/Nickel Metal-Organic Framework Nanosheets for Non-Enzymatic Electrochemical Glucose Detection

Metal-organic frameworks (MOFs) have broad potential applications in electrochemical glucose detection. Herein, a green ultrasonic synthesis process is presented for preparing two-dimensional (2D) copper-nickel metal-organic framework nanosheets (CuNi-MOFNs) for glucose detection. The synthesized CuNi-MOFNs were characterized using scanning electron microscopy (SEM), scanning transmission electron microscope (STEM), X-ray diffractometer (XRD), and X-ray photoelectron spectrometer (XPS). The CuNi-MOFN nanocomposites were used to cover the glassy carbon electrode (GCE) and the CuNi-MOFNs-modified electrode was studied in alkaline media. Cyclic voltammetry (CV) and amperometric i-t curves indicated that the CuNi-MOFNs-modified electrode revealed great electrochemical performances towards glucose oxidation. Due to the ease of access to active metal sites in large specific surface of nanosheets, the CuNi-MOFNs-modified electrode can effectively improve the electronic transfer rate and enhance electrocatalytic activity of the CuNi-MOFNs-modified electrode. The CuNi-MOFNs-modified electrode showed electrochemical performances for glucose detection with a linear range from 0.01 mM to 4 mM, sensitivity of 702 μAmM-1cm-2, and detection limit of 3.33 μΜ (S/N = 3). The CuNi-MOFNs-modified electrode exhibited excellent anti-interference ability and high selectivity in glucose measurements. Hence, the CuNi-MOFNs-modified electrode has good, promising prospects in non-enzymatic electrochemical glucose detection.

Gold Nanorods with Mesoporous Silica Shell: A Promising Platform for Cisplatin Delivery

The versatile combination of metal nanoparticles with chemotherapy agents makes designing multifunctional drug delivery systems attractive. In this work, we reported cisplatin's encapsulation and release profile using a mesoporous silica-coated gold nanorods system. Gold nanorods were synthesized by an acidic seed-mediated method in the presence of cetyltrimethylammonium bromide surfactant, and the silica-coated state was obtained by modified Stöber method. The silica shell was modified first with 3-aminopropyltriethoxysilane and then with succinic anhydride to obtain carboxylates groups to improve cisplatin encapsulation. Gold nanorods with an aspect ratio of 3.2 and silica shell thickness of 14.74 nm were obtained, and infrared spectroscopy and ζ potential studies corroborated surface modification with carboxylates groups. On the other hand, cisplatin was encapsulated under optimal conditions with an efficiency of ~58%, and it was released in a controlled manner over 96 h. Furthermore, acidic pH promoted a faster release of 72% cisplatin encapsulated compared to 51% in neutral pH.

Porphin e6 complex loaded with gold nanorod mesoporous silica enhances photodynamic therapy in ovarian cancer cells in vitro

A growing amount of experimental evidence has proven that the application of gold nanorods (AuNRs) in photodynamic therapy (PDT) can significantly enhance its therapeutic efficacy. The aim of this study was to establish a protocol for investigating the effect of gold nanorods loaded with the photosensitizer chlorin e6 (Ce6) on photodynamic therapy in the OVCAR3 human ovarian cancer cell line in vitro and to determine whether the PDT effect was different from that of Ce6 alone. OVCAR3 cells were randomly divided into three groups: the control group, Ce6-PDT group, and AuNRs@SiO₂@Ce6-PDT group. Cell viability was measured by MTT assay. The generation of reactive oxygen species (ROS) was measured by a fluorescence microplate reader. Cell apoptosis was detected by flow cytometry. The expression of apoptotic proteins was detected by immunofluorescence and western blotting. The results showed that compared with that of the Ce6-PDT group, the cell viability of the AuNRs@SiO₂@Ce6-PDT group was significantly decreased (P < 0.05) in a dose-dependent manner, and ROS production increased significantly (P < 0.05). The flow cytometry results showed that the proportion of apoptotic cells in the AuNRs@SiO₂@Ce6-PDT group was significantly higher than that in the Ce6-PDT group (P < 0.05). Immunofluorescence and western blot results showed that the protein expression levels of cleaved caspase-9, cleaved caspase-3, cleaved PARP, and Bax in the AuNRs@SiO₂@Ce6-PDT-treated-OVCAR3 cells were higher than those in the Ce6-PDT-treated cells (P < 0.05), and the protein expression levels of caspase-3, caspase-9, PARP, and Bcl-2 were slightly lower than those in the Ce6-PDT group (P < 0.05). In summary, our results show that AuNRs@SiO₂@Ce6-PDT has a significantly stronger effect on OVCAR3 cells than the effect of Ce6-PDT alone. The mechanism may be related to the expression of Bcl-2 family and caspase family in the mitochondrial pathway.

Thermosensitive Biomimetic Hybrid Membrane Camouflaged Hollow Gold Nanoparticles for NIR-Responsive Mild-Hyperthermia Chemo-/Photothermal Combined Tumor Therapy

As an appealing biomimetic strategy for various medical applications, cell membrane coating lacks sensitive on-demand breaking capability. Herein, we incorporated thermosensitive lipid (TSL) membrane into red blood cell (RBC) and MCF-7 cancer cell (MC) hybrid membrane ([RBC-MC]M) vesicles. The [RBC-MC-TSL]M was coated onto doxorubicin (Dox)-loaded hollow gold nanoparticles to enhance chemo-/photothermal combined tumor therapy at a mild hyperthermia temperature (≤49 °C). Double-layer coating with TSL and [RBC-MC-TSL]M as the inner and outer layer, respectively, presented better antileakage and higher NIR-responsivity than single-layer coating. The Dox release ratio upon NIR laser irradiation (≤49 °C) was 74.6%, much higher than that (33.5%) without NIR laser. The nanodrug can be efficiently and specifically taken up by MCF-7 cells. In addition, the nanodrug exhibited excellent tumor-targeting property, with 4.08- and 1.12-times Dox accumulation in MCF-7 tumors compared to free Dox and [RBC-MC]M-coated counterpart, respectively. Most importantly, TSL incorporation significantly enhanced NIR-responsive antitumor efficiency, with tumor growth inhibition ratio increased from 35.1% to 48.6% after a single dose administration. Besides, the nanodrug exhibited very good biocompatibility. Camouflaging nanoparticles with the thermosensitive biomimetic hybrid membrane provides a painless and promisingly clinical-applicable approach for effective chemo-/photothermal combined mild-hyperthermia tumor therapy.

Delivery of Theranostic Nanoparticles to Various Cancers by Means of Integrin-Binding Peptides

Active targeting of tumors is believed to be the key to efficient cancer therapy and accurate, early-stage diagnostics. Active targeting implies minimized off-targeting and associated cytotoxicity towards healthy tissue. One way to acquire active targeting is to employ conjugates of therapeutic agents with ligands known to bind receptors overexpressed onto cancer cells. The integrin receptor family has been studied as a target for cancer treatment for almost fifty years. However, systematic knowledge on their effects on cancer cells, is yet lacking, especially when utilized as an active targeting ligand for particulate formulations. Decoration with various integrin-targeting peptides has been reported to increase nanoparticle accumulation in tumors ≥ 3-fold when compared to passively targeted delivery. In recent years, many newly discovered or rationally designed integrin-binding peptides with excellent specificity towards a single integrin receptor have emerged. Here, we show a comprehensive analysis of previously unreviewed integrin-binding peptides, provide diverse modification routes for nanoparticle conjugation, and showcase the most notable examples of their use for tumor and metastases visualization and eradication to date, as well as possibilities for combined cancer therapies for a synergetic effect. This review aims to highlight the latest advancements in integrin-binding peptide development and is directed to aid transition to the development of novel nanoparticle-based theranostic agents for cancer therapy.

Combining histone deacetylase inhibitors (HDACis) with other therapies for cancer therapy

Histone deacetylases (HDACs) play an important role in regulating the expression of genes involved in tumorigenesis and tumor maintenance, and hence they have been considered as key targets in cancer therapy. As a novel category of antitumor agents, histone deacetylase inhibitors (HDACis) can induce cell cycle arrest, apoptosis, and differentiation in cancer cells, ultimately combating cancer. Although in the United States, the use of HDACis for the treatment of certain cancers has been approved, the therapeutic efficacy of HDACis as a single therapeutic agent in solid tumorshas been unsatisfactory and drug resistance may yet occur. To enhance therapeutic efficacy and limit drug resistance, numerous combination therapies involving HDACis in synergy with other antitumor therapies have been studied. In this review, we describe the classification of HDACs. Moreover, we summarize the antitumor mechanism of the HDACis for targeting key cellular processes of cancers (cell cycle, apoptosis, angiogenesis, DNA repair, and immune response). In addition, we outline the major developments of other antitumor therapies in combination with HDACis, including chemotherapy, radiotherapy, phototherapy, targeted therapy, and immunotherapy. Finally, we discuss the current state and challenges of HDACis-drugs combinations in future clinical studies, with the aim of optimizing the antitumor effect of such combinations.

Folic acid and deoxycholic acid derivative modified Fe3O4 nanoparticles for efficient pH-dependent drug release and multi-targeting against liver cancer cells

The novel nano-drug carrier (FDCA-FA-MNPs) was constructed by grafting formyl deoxycholic acid (FDCA) and folic acid (FA) on the surface of Fe3O4 magnetic nanoparticles (MNPs), possessing the advantages of superparamagnetism, good stability, low cytotoxicity and good blood compatibility. The hydrophobic anti-cancer drug doxorubicin hydrochloride (DOX) was successfully loaded onto FDCA-FA-MNPs through supramolecular interactions (hydrogen bond between FDCA and drug and hydrophobic interaction and π-π stacking between drug and drug). The drug loading amount and drug loading capacity were 509.1 mg g-1 and 33.73 wt%, respectively. In addition, drug release had a pH responsive and controllable release performance, the release rate at pH 5.3 (45.6%) was four times that at pH 7.4 (11.5%), and the tumor microenvironment was favorable for drug release. More importantly, the novel nano-drug carrier combined the hepatocellular targeting of FDCA, the cancer cell targeting of FA, and the magnetic targeting of Fe3O4, showing excellent cancer-killing efficiency (78%) in vitro. Therefore, the nano-drug carrier synthesized in this paper has potential practical application value in the targeted therapy of liver cancer.

Topically applied liposome-in-hydrogels for systematically targeted tumor photothermal therapy

Transdermal drug delivery for local or systemic therapy provides a potential anticancer modality with a high patient compliance. However, the drug delivery efficiency across the skin is highly challenging due to the physiological barriers, which limit the desired therapeutic effects. In this study, we prepared liposome-in-hydrogels containing a tumor targeting photosensitizer IR780 (IR780/lipo/gels) for tumor photothermal therapy (PTT). The formulation effectively delivered IR780 to subcutaneous tumor and deep metastatic sites, while the hydrogels were applied on the skin overlying the tumor or on an area of distant normal skin. The photothermal antitumor activity of topically administered IR780/lipo/gels was evaluated following laser irradiation. We observed significant inhibition of the rate of the tumor growth without any toxicity associated with the topical administration of hydrogels. Collectively, the topical administration of IR780/lipo/gels represents a new noninvasive and safe strategy for targeted tumor PTT.

Smart gating porous particles as new carriers for drug delivery

The design of smart drug delivery carriers has recently attracted great attention in the biomedical field. Smart carriers can specifically respond to physical and chemical changes in their environment, such as temperature, photoirradiation, ultrasound, magnetic field, pH, redox species, and biomolecules. This review summarizes recent advances in the integration of porous particles and stimuli-responsive gatekeepers for effective drug delivery. Their unique structural properties play an important role in facilitating the diffusion of drug molecules and cell attachment. Various techniques for fabricating porous materials, with their major advantages and limitations, are summarized. Smart gatekeepers provide advanced functions such as "open-close" switching by functionalized stimuli-responsive polymers on a particle's pores. These controlled delivery systems enable drugs to be targeted at specific rates, time programs, and sites of the human body. The gate structures, gating mechanisms, and controlled release mechanisms of each trigger are detailed. Current ongoing research and future trends in targeted drug delivery, tissue engineering, and regenerative medicine applications are highlighted.

Development of gold nanorods for cancer treatment

There has been growing interest in the application of gold nanorods (GNRs) to tumor therapy due to the unique properties they possess. In the past, GNRs were not used in clinical treatments as they lacked stability in vivo and were characterized by potential toxicity. Despite these issues, the significant potential for utilizing GNRs to conduct safe and effective treatments for tumors cannot be ignored. Therefore, it remains crucial to thoroughly investigate the mechanisms behind the toxicity of GNRs in order to provide the means of overcoming obstacles to its full application in the future. This review presents the toxic effects of GNRs, the factors affecting toxicity and the methods to improve biocompatibility, all of which are presently being studied. Finally, we conclude by briefly discussing the current research status of GNRs and provide additional perspective on the challenges involved along with the course of development for GNRs in the future.

Plasmonically Modulated Gold Nanostructures for Photothermal Ablation of Bacteria

With the wide utilization of antibiotics, antibiotic-resistant bacteria have been often developed more frequently to cause potential global catastrophic consequences. Emerging photothermal ablation has been attracting extensive research interest for quick/effective eradication of pathogenic bacteria from contaminated surroundings and infected body. In this field, anisotropic gold nanostructures with tunable size/morphologies have been demonstrated to exhibit their outstanding photothermal performance through strong plasmonic absorption of near-infrared (NIR) light, efficient light to heat conversion, and easy surface modification for targeting bacteria. To this end, this review first introduces thermal treatment of infectious diseases followed by photothermal therapy via heat generation on NIR-absorbing gold nanostructures. Then, the usual synthesis and spectral features of diversified gold nanostructures and composites are systematically overviewed with the emphasis on the importance of size, shape, and composition to achieve strong plasmonic absorption in NIR region. Further, the innovated photothermal applications of gold nanostructures are comprehensively demonstrated to combat against bacterial infections, and some constructive suggestions are also discussed to improve photothermal technologies for practical applications.

Ultra-high thermally stable gold nanorods/radial mesoporous silica and their application in enhanced chemo-photothermal therapy

In this work, gold nanorods embedded in ultra-thick silica shells with radial mesopores (AuNR/R-SiO₂) were successfully synthesized in an ethanol/water solution. By optimizing the concentration of CTAB and the volume of ethanol, a shell thickness up to 83 nm was realized. Taking advantage of the ultra-thick silica shell, AuNR/R-SiO₂ exhibited ultra-high thermal stability—could retain the integrity and photothermal effects even after 800 °C thermal annealing, providing inspiring sights into the application under some extreme conditions. After continuous irradiation for twenty times, the photothermal effects of AuNRs coated with R-SiO₂ still remained perfect without performance degradation and shape change. Besides, abundant mesopores could effectively improve the photothermal conversion efficiency of AuNRs. AuNR/R-SiO₂ exhibited an outstanding loading capacity up to 2178 mg g⁻¹ with doxorubicin (DOX) as the model drug, and the release behaviors could be nicely controlled by acidity and near-infrared (NIR) laser to achieve the “On-demand” mode. In vitro experiments showed that AuNR/R-SiO₂ were biocompatible and easy to be internalized by HeLa cells. In addition, due to the ultra-thick silica shell, the effect of the combined chemo-photothermal therapy using AuNR/R-SiO₂/DOX was significantly enhanced, showing a higher therapeutic efficiency than single chem- or photothermal therapy. It was worth noting that AuNR/R-SiO₂ are effective and promising for drug delivery and tumor therapy.

AuNRs coated with ultra-thick SiO₂ shells exhibited ultra-high thermal stability (800 °C), excellent photothermal conversion efficiency (70%) and outstanding loading capacity. The drug release could be nicely controlled by acidity and NIR laser to achieve the “On-demand” mode.

Receptor-Mediated In Vivo Targeting of Breast Cancer Cells with 17α-Ethynylestradiol-Conjugated Silica-Coated Gold Nanoparticles

Efficient therapies for breast cancer remain elusive because of the lack of strategies for targeted transport and receptor-mediated uptake of synthetic drug molecules by cancer cells. Conjugation of nanoparticles (NPs) with active targeting ligands enabling selective molecular recognition of antigens expressed on the surface of cancer cells is promising for localization and treatment of malignant cells. In this study, covalent attachment of synthetic estrogen 17α-ethynylestradiol on the silica (SiO₂) shell of silica-gold NPs (SiO₂@Au) was undertaken to improve the cancer-targeting ability of the nano-biotags. Chemical and structural analysis of the bioconjugates examined in solution (UV-vis and ξ-potential) and solid state (Fourier transform infrared spectroscopy, X-ray diffractometry, and transmission electron microscopy) confirmed the identity of the carrier particles and surface-bound ligands. The mesoporous silica shell served as a reservoir for anticancer drugs (doxorubicin and quercetin) and to facilitate covalent attachment of receptor molecules by click chemistry protocols. The chemoselective recognition between the nanoconjugates and cell membranes was successfully demonstrated by the accumulation of nanoprobes in the tumor tissue of mice with subcutaneous breast cancer, whereas healthy cells were unaffected. The drug release studies showed sustained release kinetics over several weeks. These findings elaborate the exceptional selectivity and potential of estrogen-coated nano-biolabels in efficient diagnosis and detection of breast cancer cells.

Rational design of yolk-shell nanostructures for drug delivery

Yolk-shell nanoparticles (YSNPs) are a new class of hollow nanostructures, and their unique properties can be utilized in drug delivery systems. The recent progress in YSNPs-based carriers is highlighted in drug delivery systems. Doxorubicin hydrochloride, ceftriaxone sodium, and methotrexate are three of the most common drugs that are used in this field. According to the reported studies, the materials used most often as yolk-shells are magnetic nanoparticles and polymers. The used methods for synthesizing a diverse array of YSNPs are classified based on their core structures. Various properties of YSNPs include their high drug-loading capacity, and their ability to decrease drug toxicity and satisfactorily and efficiently release drugs.

The Pimpled Gold Nanosphere: A Superior Candidate for Plasmonic Photothermal Therapy

BACKGROUND

The development of highly efficient nanoparticles to convert light to heat for anti-cancer applications is quite a challenging field of research.

METHODS

In this study, we synthesized unique pimpled gold nanospheres (PGNSs) for plasmonic photothermal therapy (PPTT). The light-to-heat conversion capability of PGNSs and PPTT damage at the cellular level were investigated using a tissue phantom model. The ability of PGNSs to induce robust cellular damage was studied during cytotoxicity tests on colorectal adenocarcinoma (DLD-1) and fibroblast cell lines. Further, a numerical model of plasmonic (COMSOL Multiphysics) properties was used with the PPTT experimental assays.

RESULTS

A low cytotoxic effect of thiolated polyethylene glycol (SH-PEG400-SH-) was observed which improved the biocompatibility of PGNSs to maintain 89.4% cell viability during cytometry assays (in terms of fibroblast cells for 24 hrs at a concentration of 300 µg/mL). The heat generated from the nanoparticle-mediated phantom models resulted in ΔT=30°C, ΔT=23.1°C and ΔT=21°C for the PGNSs, AuNRs, and AuNPs, respectively (at a 300 µg/mL concentration and for 325 sec). For the in vitro assays of PPTT on cancer cells, the PGNS group induced a 68.78% lethality (apoptosis) on DLD-1 cells. Fluorescence microscopy results showed the destruction of cell membranes and nuclei for the PPTT group. Experiments further revealed a penetration depth of sufficient PPTT damage in a physical tumor model after hematoxylin and eosin (H&E) staining through pathological studies (at depths of 2, 3 and 4 cm). Severe structural damages were observed in the tissue model through an 808-nm laser exposed to the PGNSs.

CONCLUSION

Collectively, such results show much promise for the use of the present PGNSs and photothermal therapy for numerous anti-cancer applications.

Facile Construction of i-Motif DNA-Conjugated Gold Nanostars as Near-Infrared and pH Dual-Responsive Targeted Drug Delivery Systems for Combined Cancer Therapy

Stimuli-responsive DNA-based nanostructures have emerged as promising vehicles for intelligent drug delivery. In this study, i-motif DNA-conjugated gold nanostars (GNSs) were fabricated in a facile manner as stimuli-responsive drug delivery systems (denoted as A-GNS/DNA/DOX) for the treatment of cancer via combined chemo-photothermal therapy. The i-motif DNA is sensitive to the environmental pH and can switch from a single-stranded structure to a C-tetrad (i-motif) structure as the environmental pH decreases from neutral (∼7.4) to acidic (<6.0). The loaded drug can then be released along with the conformational changes. To enhance cellular uptake and improve cancer cell selectivity, the aptamer AS1411, which recognizes nucleolins, was employed as a targeting moiety. The A-GNS/DNA/DOX nanocomposites were found to be highly capable of photothermal conversion and exhibited photostability under near-infrared (NIR) irradiation, and the pH and NIR irradiation effectively triggered the drug-release behaviors. In addition, the A-GNS/DNA/DOX nanocomposites exhibited good biocompatibility. The targeting recognition enabled the A-GNS/DNA/DOX to exhibit higher cellular uptake and therapeutic efficiency than the GNS/DNA/DOX. Notably, under NIR irradiation, a synergistic effect between chemotherapy and photothermal therapy can be achieved with the proposed delivery system, which exhibits much higher therapeutic efficiency both in monolayer cancer cells and tumor spheroids as compared with a single therapeutic method. This study highlights the potential of GNS/DNA nanoassemblies for intelligent anticancer drug delivery and combined cancer therapy.

Preparation of electrospray ALG/PDA-PVP nanocomposites and their application in cancer therapy

In this study, sodium alginate (ALG)/poly dopamine (PDA)-polyvinylpyrrolidone (PVP) nanocomposites was synthesized via a one-step electrostatic spraying method. The spinning solution of ALG and dopamine was electrostatically sprayed into an alkaline solution of PVP, calcium chloride and tris buffer (pH = 8.5), in which the gelation of ALG and the polymerization of dopamine could be simultaneously triggered. PDA hence produced possesses a high photothermal conversion efficiency, while the PVP that was facilely conjugated onto the surface of nanocomposites improves the colloidal stability and compatibility of the material. Moreover, the ALG renders the nanocomposite excellent drug (doxorubicine, DOX) loading capacity. Promisingly, the temperature increment during the PTT process could promote the DOX release, thus enhancing its therapeutic effect. The in vitro/in vivo biosafety and tumor treatment experiments further corroborate that the ALG/PDA-PVP nanocomposites have remarkable biocompatibility and synergism for tumor hyperthermia and chemotherapy. Consequently, such a one-step electrospray strategy provides a new way for designing nanomaterials and is expected to significantly promote the development of organic photothermal therapeutic agents with excellent bio-compatibility.

Engineering of Porous Silica Coated Gold Nanorods by Surface-Protected Etching and Their Applications in Drug Loading and Combined Cancer Therapy

Core-shell nanostructures, specifically gold nanorods coated with porous silica (GNR@p-SiO₂), were successfully fabricated by surface-protected etching. The nanostructures, photothermal effects, drug loading and drug release behaviors, cellular uptake, and combined chemo-photothermal therapy were investigated. The results showed that the as-prepared GNR@p-SiO₂ had a uniform porous silica outer layer. Etching process could be modulated by adjusting the etching time, concentrations of etching agents, and concentrations of protective agents. With doxorubicin (DOX) as the model drug, the drug loading capacity reached 18.9%, which was dependent on the DOX concentrations. The drug release profiles were dual stimulus-responsive to pH and laser irradiation. In addition, the GNR@p-SiO₂ nanoparticles were biocompatible and effectively internalized by cancer cells. Compared with chemotherapy or photothermal therapy administered individually, combined chemo-photothermal therapy using GNR@p-SiO₂ exhibited higher efficiency in killing cancer cells both in vitro and in vivo. Therefore, surface-protected etching is a powerful method for preparing core-shell nanostructures capped with mesoporous silica for combined cancer chemo-photothermal therapy.