Exploring the Potential of Plant-Based Nanotechnology in Cancer Immunotherapy: Benefits, Limitations, and Future Perspectives

Reconceptualizing cancer immunotherapy can be improved if combined with plant production systems and nanotechnology. This review aims to contribute to the knowledge of plant use in nanomedicine and cancer immunotherapy. In the foreground, we outlined each of these approaches; nanomedicine, green synthesis, and immunotherapy. The benefits of plant-based nanoparticles in mending the immune systems were subsequently analyzed, with reference to the literature. The combining effects of biological and therapeutic properties of some phytochemicals and their derivatives, with targeted nanoparticles and selective immunotherapy, can enhance the delivery of drugs and antibodies, and induce antitumor immune responses, via activation of functions of neutrophils, lymphocyte cells, and natural killer cells, and macrophages, resulting in induced apoptosis and phagocytosis of tumor cells, which can improve designing immunotherapeutic strategies targeting cancer, with a larger spectrum compared to the current cytotoxic anticancer drugs commonly used in clinics. This study uncovers the mechanistic drivers of cancer immunoengineering in cancer therapy using plant-based nanomaterials, enhancing therapeutic benefits while minimizing toxic and side effects.

Development of Intratumoral Drug Delivery Based Strategies for Antitumor Therapy

Research for tumor treatment with significant therapy effects and minimal side-effects has been widely carried over the past few decades. Different drug forms have received a lot of attention. However, systemic biodistribution induces efficacy and safety issues. Intratumoral delivery of agents might overcome these problems because of its abundant tumor accumulation and retention, thereby reducing side effects. Delivering hydrogels, nanoparticles, microneedles, and microspheres drug carriers directly to tumors can realize not only targeted tumor therapy but also low side-effects. Furthermore, intratumoral administration has been integrated with treatment strategies such as chemotherapy, enhancing radiotherapy, immunotherapy, phototherapy, magnetic fluid hyperthermia, and multimodal therapy. Some of these strategies are ongoing clinical trials or applied clinically. However, many barriers hinder it from being an ideal and widely used option, such as decreased drug penetration impeded by collagen fibers of a tumor, drug squeezed out by high density and high pressure, mature intratumoral injection technique. In this review, we systematically discuss intratumoral delivery of different drug carriers and current development of intratumoral therapy strategies.

Biohybrid Flexible Sperm-like Microrobot for Targeted Chemo-Photothermal Therapy

Magnetic micro/nanorobots are promising platforms for targeted drug delivery, and their construction with soft and flexible features has received extensive attention for practical applications. Despite significant efforts in this field, facile fabrication of magnetic microrobots with flexible structures and versatility in targeted therapy remains a big challenge. Herein, we proposed a novel universal strategy to fabricate a biohybrid flexible sperm-like microrobot (BFSM) based on a Chlorella (Ch.) cell and artificial flagella, which showed great potential for targeted chemo-photothermal therapy for the first time. In this approach, microspherical Ch. cells were utilized to construct the microrobotic heads, which were intracellularly deposited with core-shell Pd@Au, extracellularly magnetized with Fe3O4, and further loaded with anticancer drug. The magnetic heads with excellent photothermal and chemotherapeutic capability were further assembled with flexible polypyrrole nanowires via biotin-streptavidin bonding to construct the BFSMs. Based on the exquisite head-to-tail structures, the BFSMs could be effectively propelled under precessing magnetic fields and move back and forth without a U-turn. Moreover, in vitro chemo-photothermal tests were conducted to verify their performance of targeted drug delivery toward localized HeLa cells. Due to this superior versatility and facile fabrication, the BFSMs demonstrated great potential for targeted anticancer therapy.

Multifunctional targeted solid lipid nanoparticles for combined photothermal therapy and chemotherapy of breast cancer

Photothermal therapy has emerged as a new promising strategy for the management of cancer, either alone or combined with other therapeutics, such as chemotherapy. The use of nanoparticles for multimodal therapy can improve treatment performance and reduce drug doses and associated side effects. Here we propose the development of a novel multifunctional nanosystem based on solid lipid nanoparticles co-loaded with gold nanorods and mitoxantrone and functionalized with folic acid for dual photothermal therapy and chemotherapy of breast cancer. Nanoparticles were produced using an economically affordable method and presented suitable physicochemical properties for tumor passive accumulation. Upon Near-Infrared irradiation (808 nm, 1.7 W cm^-2, 5 min), nanoparticles could effectively mediate a temperature increase of >20 °C. Moreover, exposure to light resulted in an enhanced release of Mitoxantrone. Furthermore, nanoparticles were non-hemolytic and well tolerated by healthy cells even at high concentrations. The active targeting strategy was found to be successful, as shown by the greater accumulation of the functionalized nanoparticles in MCF-7 cells. Finally, the combined effects of chemotherapy, light-induced drug release and photothermal therapy significantly enhanced breast cancer cell death. Overall, these results demonstrate that the developed lipid nanosystem is an efficient vehicle for breast cancer multimodal therapy.

Gold Nanorods: The Most Versatile Plasmonic Nanoparticles

Gold nanorods (NRs), pseudo-one-dimensional rod-shaped nanoparticles (NPs), have become one of the burgeoning materials in the recent years due to their anisotropic shape and adjustable plasmonic properties. With the continuous improvement in synthetic methods, a variety of materials have been attached around Au NRs to achieve unexpected or improved plasmonic properties and explore state-of-the-art technologies. In this review, we comprehensively summarize the latest progress on Au NRs, the most versatile anisotropic plasmonic NPs. We present a representative overview of the advances in the synthetic strategies and outline an extensive catalogue of Au-NR-based heterostructures with tailored architectures and special functionalities. The bottom-up assembly of Au NRs into preprogrammed metastructures is then discussed, as well as the design principles. We also provide a systematic elucidation of the different plasmonic properties associated with the Au-NR-based structures, followed by a discussion of the promising applications of Au NRs in various fields. We finally discuss the future research directions and challenges of Au NRs.

Development of a multi-arm polyrotaxanes modified mesoporous silica-coated gold nanoplatform for protecting endothelial progenitor cells against high glucose environment

Recent study reported that endothelial progenitor cells (EPCs) have potential to treat diabetic macroangiopathy. High glucose environment of diabetes can affect the adhesion of EPCs by decreasing the expression of CXC chemokine receptor 4 (CXCR4) and affect the proliferation of EPCs by decreasing the expression of miR-126. The results showed that the cytotoxicity of GNR@MSNs@PEI to EPCs was significantly lower than PEI; the temperature of GNR@MSNs@PEI solution can be controlled between 38-40°C under 808 nm laser irradiation. 25.67 µg of pcDNA3.1-GFP-CXCR4 and 5.36 µg of FITC-miR-126 could be loaded in 1 mg of GNR@MSNs@PEI; GNR@MSNs@PEI has gene transfection almost the same as Lipofectamine 3000. Subsequent in vitro studies showed that pcDNA3.1-GFP-CXCR4 and miR-126 loaded GNR@MSNs@PEI can significantly increase the adhesion and proliferation and decrease the apoptosis of EPCs treated with high glucose under 808 nm laser irradiation. In conclusion, nano-carriers (GNR@MSNs@PEI) with high pcDNA3.1-CXCR4 and miR-126 loading capacity, high biocompatibility, well cell internalization, and controllable release ability were constructed to transfer CXCR4 expression plasmid (pcDNA3.1-CXCR4) and miR-126 into EPCs efficiently. Further in vitro studies indicated that pcDNA3.1-CXCR4 and miR-126-loaded GNR@MSNs@PEI could protect EPCs against high glucose-induced injury.

Heat induction in two-dimensional graphene-Fe3O4 nanohybrids for magnetic hyperthermia applications with artificial neural network modeling

We report the synthesis and characterization of graphene functionalized with iron (Fe³⁺) oxide (G-Fe₃O₄) nanohybrids for radio-frequency magnetic hyperthermia application. We adopted the wet chemical procedure, using various contents of Fe₃O₄ (magnetite) from 0-100% for making two-dimensional graphene-Fe₃O₄ nanohybrids. The homogeneous dispersal of Fe₃O₄ nanoparticles decorated on the graphene surface combined with their biocompatibility and high thermal conductivity make them an excellent material for magnetic hyperthermia. The morphological and magnetic properties of the nanohybrids were studied using scanning electron microscopy (SEM) and a vibrating sample magnetometer (VSM), respectively. The smart magnetic platforms were exposed to an alternating current (AC) magnetic field of 633 kHz and of strength 9.1 mT for studying their hyperthermic performance. The localized antitumor effects were investigated with artificial neural network modeling. A neural net time-series model was developed for the assessment of the best nanohybrid composition to serve the purpose with an accuracy close to 100%. Six Nonlinear Autoregressive with External Input (NARX) models were obtained, one for each of the components. The assessment of the accuracy of the predicted results has been done on the basis of Mean Squared Error (MSE). The highest Mean Squared Error value was obtained for the nanohybrid containing 45% magnetite and 55% graphene (F₄₅G₅₅) in the training phase i.e., 0.44703, which is where the model achieved optimal results after 71 epochs. The F₄₅G₅₅ nanohybrid was found to be the best for hyperthermia applications in low dosage with the highest specific absorption rate (SAR) and mean squared error values.

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.

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.