Magnetic-Fe/Fe(3)O(4)-nanoparticle-bound SN38 as carboxylesterase-cleavable prodrug for the delivery to tumors within monocytes/macrophages

Research Progress of SN38 Drug Delivery System in Cancer Treatment

The active metabolite of irinotecan (CPT-11), 7-ethyl-10-hydroxycamptothecin (SN38), is 100-1000 times more active than CPT-11 and has shown inhibitory effects on a range of cancer cells, including those from the rectal, small cell lung, breast, esophageal, uterine, and ovarian malignancies. Despite SN38's potent anticancer properties, its hydrophobicity and pH instability have caused substantial side effects and anticancer activity loss, which make it difficult to use in clinical settings. To solve the above problems, the construction of SN38-based drug delivery systems is one of the most feasible methods to improve drug solubility, enhance drug stability, increase drug targeting ability, improve drug bioavailability, enhance therapeutic efficacy and reduce adverse drug reactions. Therefore, based on the targeting mechanism of drug delivery systems, this paper reviews SN38 drug delivery systems, including polymeric micelles, liposomal nanoparticles, polymeric nanoparticles, protein nanoparticles, conjugated drug delivery systems targeted by aptamers and ligands, antibody-drug couplings, magnetic targeting, photosensitive targeting, redox-sensitive and multi-stimulus-responsive drug delivery systems, and co-loaded drug delivery systems. The focus of this review is on nanocarrier-based SN38 drug delivery systems. We hope to provide a reference for the clinical translation and application of novel SN38 medications.

Treating Primary Aldosteronism-Induced Hypertension: Novel Approaches and Future Outlooks

Primary aldosteronism (PA) is the most common cause of secondary hypertension and is associated with increased morbidity and mortality when compared with blood pressure-matched cases of primary hypertension. Current limitations in patient care stem from delayed recognition of the condition, limited access to key diagnostic procedures, and lack of a definitive therapy option for nonsurgical candidates. However, several recent advances have the potential to address these barriers to optimal care. From a diagnostic perspective, machine-learning algorithms have shown promise in the prediction of PA subtypes, while the development of noninvasive alternatives to adrenal vein sampling (including molecular positron emission tomography imaging) has made accurate localization of functioning adrenal nodules possible. In parallel, more selective approaches to targeting the causative aldosterone-producing adrenal adenoma/nodule (APA/APN) have emerged with the advent of partial adrenalectomy or precision ablation. Additionally, the development of novel pharmacological agents may help to mitigate off-target effects of aldosterone and improve clinical efficacy and outcomes. Here, we consider how each of these innovations might change our approach to the patient with PA, to allow more tailored investigation and treatment plans, with corresponding improvement in clinical outcomes and resource utilization, for this highly prevalent disorder.

Tumor-associated macrophages in nanomaterial-based anti-tumor therapy: as target spots or delivery platforms

Targeting tumor-associated macrophages (TAMs) has emerged as a promising approach in cancer therapy. This article provides a comprehensive review of recent advancements in the field of nanomedicines targeting TAMs. According to the crucial role of TAMs in tumor progression, strategies to inhibit macrophage recruitment, suppress TAM survival, and transform TAM phenotypes are discussed as potential therapeutic avenues. To enhance the targeting capacity of nanomedicines, various approaches such as the use of ligands, immunoglobulins, and short peptides are explored. The utilization of live programmed macrophages, macrophage cell membrane-coated nanoparticles and macrophage-derived extracellular vesicles as drug delivery platforms is also highlighted, offering improved biocompatibility and prolonged circulation time. However, challenges remain in achieving precise targeting and controlled drug release. The heterogeneity of TAMs and the variability of surface markers pose hurdles in achieving specific recognition. Furthermore, the safety and clinical applicability of these nanomedicines requires further investigation. In conclusion, nanomedicines targeting TAMs hold great promise in cancer therapy, offering enhanced specificity and reduced side effects. Addressing the existing limitations and expanding our understanding of TAM biology will pave the way for the successful translation of these nano-therapies into clinical practice.

Functionalized niosomes as a smart delivery device in cancer and fungal infection

Various diseases remain untreated due to lack of suitable therapeutic moiety or a suitable drug delivery device, especially where toxicities and side effects are the primary reason for concern. Cancer and fungal infections are diseases where treatment schedules are not completed due to severe side effects or lengthy treatment protocols. Advanced treatment approaches such as active targeting and inhibition of angiogenesis may be preferred method for the treatment for malignancy over the conventional method. Niosomes may be a better alternative drug delivery carrier for various therapeutic moieties (either hydrophilic or hydrophobic) and also due to ease of surface modification, non-immunogenicity and economical. Active targeting approach may be done by targeting the receptors through coupling of suitable ligand on niosomal surface. Moreover, various receptors (CD44, folate, epidermal growth factor receptor (EGFR) & Vascular growth factor receptor (VGFR)) expressed by malignant cells have also been reviewed. The preparation of suitable niosomal formulation also requires considerable attention, and its formulation depends upon various factors such as selection of non-ionic surfactant, method of fabrication, and fabrication parameters. A combination therapy (dual drug and immunotherapy) has been proposed for the treatment of fungal infection with special consideration for surface modification with suitable ligand on niosomal surface to sensitize the receptors (C-type lectin receptors, Toll-like receptors & Nucleotide-binding oligomerization domain-like receptors) present on immune cells involved in fungal immunity. Certain gene silencing concept has also been discussed as an advanced alternative treatment for cancer by silencing the mRNA at molecular level using short interfering RNA (si-RNA).

Tumor Associated Macrophages and TAMs-Based Anti-Tumor Nanomedicines

As an important part of tumor microenvironment, tumor associated macrophages (TAMs) play a vital role in the occurrence, development, invasion, and metastasis of many malignant tumors and can significantly promote the formation of tumor blood vessels and lymphatic vessels, hence TAMs are greatly associated with poor prognosis. The research on nanomedicine has achieved huge progress, and nano-drugs have been widely utilized to treat various diseases through different mechanisms. Therefore, developing nano-drugs that are based on TAMs-associated anti-tumor mechanisms to effectively suppress tumor growth is expected to be a promising research filed. This paper introduces relevant information about TAMs in terms of their origin, and their roles in tumor genesis, development and metastasis. Furthermore, TAMs-related anti-tumor nano-drugs are summarized. Specifically, a wide range of nano-drugs targeting at TAMs are introduced, and categorized according to their therapeutic mechanisms toward tumors. Additionally, various nano delivery platforms using TAMs as cell carriers which aim at inhibiting tumor growth are reviewed. These two parts elucidate that the exploration of nanomedicine is essential to the study on TAMs-related anti-tumor strategies. This review is also intended to provide novel ideas for in-depth investigation on anti-tumor molecular mechanisms and nano-drug delivery systems based on TAMs.

A narrative review of tumor-associated macrophages in lung cancer: regulation of macrophage polarization and therapeutic implications

Lung cancer is the deadliest malignancy worldwide. An inflammatory microenvironment is a key factor contributing to lung tumor progression. Tumor-Associated Macrophages (TAMs) are prominent components of the cancer immune microenvironment with diverse supportive and inhibitory effects on growth, progression, and metastasis of lung tumors. Two main macrophage phenotypes with different functions have been identified. They include inflammatory or classically activated (M1) and anti-inflammatory or alternatively activated (M2) macrophages. The contrasting functions of TAMs in relation to lung neoplasm progression stem from the presence of TAMs with varying tumor-promoting or anti-tumor activities. This wide spectrum of functions is governed by a network of cytokines and chemokines, cell-cell interactions, and signaling pathways. TAMs are promising therapeutic targets for non-small cell lung cancer (NSCLC) treatment. There are several strategies for TAM targeting and utilizing them for therapeutic purposes including limiting monocyte recruitment and localization through various pathways such as CCL2-CCR2, CSF1-CSF1R, and CXCL12-CXCR4, targeting the activation of TAMs, genetic and epigenetic reprogramming of TAMs to antitumor phenotype, and utilizing TAMs as the carrier for anti-cancer drugs. In this review, we will outline the role of macrophages in the lung cancer initiation and progression, pathways regulating their function in lung cancer microenvironment as well as the role of these immune cells in the development of future therapeutic strategies.

Therapeutic strategies of iron-based nanomaterials for cancer therapy

Iron-based nanomaterials have appeared in various cancer treatments owing to their promising functions and safety. Various sophisticated iron-based nanomaterials have been designed to exhibit great therapeutic effects through different strategies. Given the rapid progression, there is a great need to integrate the recent advances to learn about the latest innovation in this field. In this review, we classified the strategies of iron-based nanomaterials for cancer treatment into the following categories: immunotherapy, ferroptosis, magnetic hyperthermia and magneto-mechanical destruction. On the one hand, we discussed the underlining mechanism of iron-based nanomaterials in these therapies and applications; on the other hand, we analyzed the feasible combination of these applications and other therapies. Finally, the current challenges and expectation of iron-based nanomaterials in this field were highlighted.

How to use macrophages to realise the treatment of tumour

Macrophages (Mø) are immune cells with natural phagocytic ability and play an important role in tumorigenesis, development and metastasis. Mø play a dual role of tumour inhibition and tumour promotion in tumour development due to their two different phenotypes. Mø in the tumour microenvironment have long been referred to as tumour-associated Mø (TAMs). Mø are mainly involved in tumour resistance, cancer metastasis and mediating immunosuppression. Nowadays, Mø and Mø membranes have been widely used in drug delivery systems (DDSs) because of their good biocompatibility, natural phagocytosis and their important role in tumour development. In this review, from the perspective of Mø's role in tumour development, we present strategies and drugs of Mø targeting and focusing on the several types of biomimetic nanoparticles constructed by Mø and Mø membranes in tumour therapy, and discuss the problem of this delivery system in present research and future directions.

Magnetic and near-infrared derived heating characteristics of dimercaptosuccinic acid coated uniform Fe@Fe3O4 core-shell nanoparticles

Among the number of hyperthermia materials, magnetic nanoparticles have received much attention. In this work, we studied the heating characteristics of uniform Fe@Fe3O4 core-shell nanoparticle under near-infrared laser irradiation and external AC magnetic field applying. The Fe@Fe3O4 core-shell nanoparticles were prepared by thermal decomposition of iron pentacarbonyl and followed by controlled oxidation. The prepared uniform particles were further coated with dimercaptosuccinic acid to make them well dispersed in water. Near-infrared derived photothermal study of solutions containing a different concentration of the core-shell nanoparticles was made by using 808 nm laser Source. Additionally, magnetic hyperthermia ability of the Fe@Fe3O4 nanoparticle at 150 kHz and various oersted (140-180 Oe) condition was systemically characterized. The Fe@Fe3O4 nanoparticles which exhibited effective photo and magnetic hyperthermia are expected to be used in biomedical application.

Stimuli-responsive prodrug-based cancer nanomedicine

The rapid development of nanotechnology results in the emergence of nanomedicines, but the effective delivery of drugs to tumor sites remains a great challenge. Prodrug-based cancer nanomedicines thus emerged due to their unique advantages, including high drug load efficiency, reduced side effects, efficient targeting, and real-time controllability. A distinctive characteristic of prodrug-based nanomedicines is that they need to be activated by a stimulus or multi-stimulus to produce an anti-tumor effect. A better understanding of various responsive approaches could allow researchers to perceive the mechanism of prodrug-based nanomedicines effectively and further optimize their design strategy. In this review, we highlight the stimuli-responsive pathway of prodrug-based nanomedicines and their anticancer applications. Furthermore, various types of prodrug-based nanomedicines, recent progress and prospects of stimuli-responsive prodrug-based nanomedicines and patient data in the clinical application are also summarized. Additionally, the current development and future challenges of prodrug-based nanomedicines are discussed. We expect that this review will be valuable for readers to gain a deeper understanding of the structure and development of prodrug-based cancer nanomedicines to design rational and effective drugs for clinical use.

Magnetic Nanomaterials for Magnetically-Aided Drug Delivery and Hyperthermia

Magnetic nanoparticles have continuously gained importance for the purpose of magnetically-aided drug-delivery, magnetofection, and hyperthermia. We have summarized significant experimental approaches, as well as their advantages and disadvantages with respect to future clinical translation. This field is alive and well and promises meaningful contributions to the development of novel cancer therapies.

Synergistic Coupling Derived Cobalt Oxide with Nitrogenated Holey Two-Dimensional Matrix as an Efficient Bifunctional Catalyst for Metal-Air Batteries

Developing cost-effective, efficient bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is the heart of metal-air batteries as a renewable-energy technology. Herein, well-distributed nanopolyhedron (NP) Co₃O₄ grown on iron (Fe) encapsulated in graphitic layers on a nitrogenated, porous two-dimensional (2D) structure, namely, a C₂N matrix, (NP Co₃O₄/Fe@C₂N), presents an outstanding bifunctional catalytic activity with a comparable overpotential and Tafel slope to those of benchmark Pt/C and IrO₂. The rationally designed atomic configuration of Co₃O₄ on the C₂N matrix has a well-controlled NP morphology with a (111) plane, leading to bifunctional activities for the ORR and OER. Interestingly, the specific interaction between the NP Co₃O₄ nanoparticles and the C₂N matrix introduces synergistic coupling and changes the electronic configuration of Co atoms and the C₂N framework. Benefiting from the synergistic coupling of Co₃O₄ with the C₂N matrix, the NP Co₃O₄/Fe@C₂N electrocatalyst exhibits exceptionally high stability and an even lower charge-discharge overpotential gap of 0.85 V at 15 mA cm^-2 than that of the Pt/C+IrO₂ catalyst (1.01 V) in Zn-air batteries. This work provides insights into the rational design of a metal oxide on a C₂N matrix for bifunctional, low-cost electrochemical catalysts.

Macrophages as delivery vehicles for anticancer agents

The delivery of anticancer agents via passive approaches such as the enhanced permeability and retention effect is unlikely to achieve sufficient concentrations throughout the tumor volume for effective treatment. Cell-based delivery approaches using tumor tropic cells have the potential to overcome the limitations of passive approaches. Specifically, this review focuses on the use of monocytes/macrophages for the delivery of a variety of anticancer agents, including nanoparticles, chemotherapeutics and gene constructs. The efficacy of this delivery approach, both as monotherapy and in combination with light-based phototherapy modalities, has been demonstrated in numerous in vitro and animal studies, however, its clinical potential remains to be determined.

Hydrophobized SN38 to redox-hypersensitive nanorods for cancer therapy

Redox-hypersensitive hydrophobized SN38 self-assembled into rod-shaped nanoaggregates with uncompromised in vitro cytotoxicity and potent in vivo antitumor effects.

Early detection of pancreatic cancers in liquid biopsies by ultrasensitive fluorescence nanobiosensors

Numerous proteases, such as matrix metalloproteinases (MMPs), cathepsins (CTS), and urokinase plasminogen activator (UpA), are dysfunctional (that is, over- or under-expressed) in solid tumors, when compared to healthy human subjects. This offers the opportunity to detect early tumors by liquid biopsies. This approach is of particular advantage for the early detection of pancreatic cancer, which is a "silent killer". We have developed fluorescence nanobiosensors for ultrasensitive (sub-femtomolar) arginase and protease detection, consisting of water-dispersible Fe/Fe₃O₄ core/shell nanoparticles and two tethered fluorescent dyes: TCPP (Tetrakis(4-carboxyphenyl)porphyrin) and cyanine 5.5. Upon posttranslational modification or enzymatic cleavage, the fluorescence of TCPP increases, which enables the detection of proteases at sub-femtomolar activities utilizing conventional plate readers. We have identified an enzymatic signature for the detection of pancreatic adenocarcinomas in serum, consisting of arginase, matrix metalloproteinase-1, -3, and - 9, cathepsin-B and -E, urokinase plasminogen activator, and neutrophil elastase, which is a potential game-changer.

High-Temperature Stress Alleviation by Selenium Nanoparticle Treatment in Grain Sorghum

The role of selenium nanoparticles (Se-NPs) in the mitigation of high-temperature (HT) stress in crops is not known. The uptake, toxicity and physiological and biological effects of Se-NPs under HT were investigated in grain sorghum [Sorghum bicolor (L.) Moench]. Se-NPs of size 10-40 nm were synthesized and characterized to indicate nanocrystalline structure. A toxicity assay showed that Se-NPs concentration inducing 50% cell mortality (TC50) was 275 mg L^-1. Translocation study indicated that Se-NPs can move from root to shoot of sorghum plants. Foliar spray of 10 mg L^-1 Se-NPs during the booting stage of sorghum grown under HT stress stimulated the antioxidant defense system by enhancing antioxidant enzymes activity. Furthermore, it decreased the concentration of signature oxidants. Se-NPs facilitated higher levels of unsaturated phospholipids. Se-NPs under HT stress improved the pollen germination percentage, leading to a significantly increased seed yield. The increased antioxidant enzyme activity and decreased content of oxidants in the presence of Se-NPs were greater under HT (38/28 °C) than under optimum temperature conditions (32/22 °C). In conclusion, Se-NPs can protect sorghum plants by enhanced antioxidative defense system under HT stress.

Peptide nanosponges designed for rapid uptake by leukocytes and neural stem cells

The structure of novel binary nanosponges consisting of (cholesterol-(K/D)_nDEVDGC)₃-trimaleimide units possessing a trigonal maleimide linker, to which either lysine (K)₂₀ or aspartic acid (D)₂₀ are tethered, has been elucidated by means of TEM. A high degree of agreement between these findings and structure predictions through explicit solvent and then coarse-grained molecular dynamics (MD) simulations has been found. Based on the nanosponges' structure and dynamics, caspase-6 mediated release of the model drug 5(6)-carboxyfluorescein has been demonstrated. Furthermore, the binary (DK20) nanosponges have been found to be virtually non-toxic in cultures of neural progenitor cells. It is of a special importance for the future development of cell-based therapies that DK20 nanosponges were taken up efficiently by leucocytes (WBC) in peripheral blood within 3 h of exposure. The percentage of live cells among the WBC was not significantly decreased by the DK20 nanosponges. In contrast to stem cell or leucocyte cell cultures, which have to be matched to the patient, autologous cells are optimal for cell-mediated therapy. Therefore, the nanosponges hold great promise for effective cell-based tumor targeting.

Nanosponges for drug delivery.

Tumor-associated macrophages, potential targets for cancer treatment

The fact that various immune cells, including macrophages, can be found in tumor tissues has long been known. With the introduction of concept that macrophages differentiate into a classically or alternatively activated phenotype, the role of tumor-associated macrophages (TAMs) is now beginning to be elucidated. TAMs act as "protumoral macrophages", contributing to disease progression. As the relationship between TAMs and malignant tumors becomes clearer, TAMs are beginning to be seen as potential therapeutic targets in these cases. In this review, we will discuss how TAMs can be used as therapeutic targets of cancer in clinics.

Tumor-Associated Macrophages as Target for Antitumor Therapy

It is well known that the microenvironment of solid tumors is rich in inflammatory cells that influence tumor growth and development. Macrophages, called tumor-associated macrophages (TAMs), are the most abundant immune cell population present in tumor tissue. Several studies have demonstrated that the density of TAMs is associated with a poor prognosis and positively correlates with tumor growth. Several studies have proved that TAMs may activate and protect tumor stem cells, stimulate their proliferation as well as promote angiogenesis and metastasis. Furthermore, TAMs-derived cytokines and other proteins, such as CCL-17, CCL-22, TGF-β, IL-10, arginase 1, and galectin-3, make a significant contribution to immunosuppression. Since TAMs influence various aspects of cancer progression, there are many attempts to use them as a target for immunotherapy. The numerous studies have shown that the primary tumor growth and the number of metastatic sites can be significantly decreased by decreasing the population of macrophages in tumor tissue, for example, by blocking recruitment of monocytes or eliminating TAMs already present in the tumor tissue. Moreover, there are attempts at reprogramming TAMs into proinflammatory M1 macrophages or neutralizing the protumoral products of TAMs. Another approach uses TAMs for anticancer drug delivery into the tumor environment. In this review, we would like to summarize the clinical and preclinical trials that were focused on macrophages as a target for anticancer therapies.

Synergy of Iron Chelators and Therapeutic Peptide Sequences Delivered via a Magnetic Nanocarrier

Here, we report the synthesis, characterization, and efficacy study of Fe/Fe₃O₄-nanoparticles that were co-labeled with a tumor-homing and membrane-disrupting oligopeptide and the iron-chelator Dp44mT, which belongs to the group of the thiosemicarbazones. Dp44mT and the peptide sequence PLFAERL(_D[KLAKLAKKLAKLAK])CGKRK were tethered to the surface of Fe/Fe₃O₄ core/shell nanoparticles by utilizing dopamine-anchors. The 26-mer contains two important sequences, which are the tumor targeting peptide CGKRK, and _D[KLAKLAK]₂, known to disrupt the mitochondrial cell walls and to initiate programmed cell death (apoptosis). It is noteworthy that Fe/Fe₃O₄ nanoparticles can also be used for MRI imaging purposes in live mammals. In a first step of this endeavor, the efficacy of this nanoplatform has been tested on the highly metastatic 4T1 breast cancer cell line. At the optimal ratio of PLFAER_D[KLAKLAK]₂CGKRK to Dp44mT of 1 to 3.2 at the surface of the dopamine-coated Fe/Fe₃O₄-nanocarrier, the IC₅₀ value after 24 h of incubation was found to be 2.2 times lower for murine breast cancer cells (4T1) than for a murine fibroblast cell line used as control. Based on these encouraging results, the reported approach has the potential of leading to a new generation of nanoplatforms for cancer treatment with considerably enhanced selectivity towards tumor cells.

Experimental Investigation of Magnetic Nanoparticle-Enhanced Microwave Hyperthermia

The objective of this study was to evaluate microwave heating enhancements offered by iron/iron oxide nanoparticles dispersed within tissue-mimicking media for improving efficacy of microwave thermal therapy. The following dopamine-coated magnetic nanoparticles (MNPs) were considered: 10 and 20 nm diameter spherical core/shell Fe/Fe₃O₄, 20 nm edge-length cubic Fe₃O₄, and 45 nm edge-length/10 nm height hexagonal Fe₃O₄. Microwave heating enhancements were experimentally measured with MNPs dissolved in an agar phantom, placed within a rectangular waveguide. Effects of MNP concentration (2.5-20 mg/mL) and microwave frequency (2.0, 2.45 and 2.6 GHz) were evaluated. Further tests with 10 and 20 nm diameter spherical MNPs dispersed within a two-compartment tissue-mimicking phantom were performed with an interstitial dipole antenna radiating 15 W power at 2.45 GHz. Microwave heating of 5 mg/mL MNP-agar phantom mixtures with 10 and 20 nm spherical, and hexagonal MNPs in a waveguide yielded heating rates of 0.78 ± 0.02 °C/s, 0.72 ± 0.01 °C/s and 0.51 ± 0.03 °C/s, respectively, compared to 0.5 ± 0.1 °C/s for control. Greater heating enhancements were observed at 2.0 GHz compared to 2.45 and 2.6 GHz. Heating experiments in two-compartment phantoms with an interstitial dipole antenna demonstrated potential for extending the radial extent of therapeutic heating with 10 and 20 nm diameter spherical MNPs, compared to homogeneous phantoms (i.e., without MNPs). Of the MNPs considered in this study, spherical Fe/Fe₃O₄ nanoparticles offer the greatest heating enhancement when exposed to microwave radiation. These nanoparticles show strong potential for enhancing the rate of heating and radial extent of heating during microwave hyperthermia and ablation procedures.

Macrophages as Active Nanocarriers for Targeted Early and Adjuvant Cancer Chemotherapy

Taking advantage of the highly permeable vasculature and lack of lymphatic drainage in solid tumors (EPR effect), nanosized drug delivery systems or nanomedicines have been extensively explored for tumor-targeted drug delivery. However, in most clinical cases tumors such as the early stage tumors and post-surgery microscopic residual tumors have not yet developed such pathological EPR features, i.e., EPR-deficient. Therefore, nanomedicines may not be applicable for such these tumors. Macrophages by nature can actively home and extravasate through the tight vascular wall into tumors and migrate to their hypoxic regions, and possess perfect stealth ability for long blood circulation and impressive phagocytosis for drug loadings. Thus, nanomedicines loaded in macrophages would harness both merits and gain the active tumor homing capability independent of the EPR effect for treatments of the EPR-deficient tumors. Herein, the critical considerations, current progress, challenges and future prospects of macrophages as carriers for nanomedicines are summarized, aiming at rational design of EPR-independent tumor-targeting active nanomedicines for targeted early and adjuvant cancer chemotherapy.

Early breast cancer screening using iron/iron oxide-based nanoplatforms with sub-femtomolar limits of detection

Proteases, including matrix metalloproteinases (MMPs), tissue serine proteases, and cathepsins (CTS) exhibit numerous functions in tumor biology. Solid tumors are characterized by changes in protease expression levels by tumor and surrounding tissue. Therefore, monitoring protease levels in tissue samples and liquid biopsies is a vital strategy for early cancer detection. Water-dispersable Fe/Fe3O4-core/shell based nanoplatforms for protease detection are capable of detecting protease activity down to sub-femtomolar limits of detection. They feature one dye (tetrakis(carboxyphenyl)porphyrin (TCPP)) that is tethered to the central nanoparticle by means of a protease-cleavable consensus sequence and a second dye (Cy 5.5) that is directly linked. Based on the protease activities of urokinase plasminogen activator (uPA), MMPs 1, 2, 3, 7, 9, and 13, as well as CTS B and L, human breast cancer can be detected at stage I by means of a simple serum test. By monitoring CTS B and L stage 0 detection may be achieved. This initial study, comprised of 46 breast cancer patients and 20 apparently healthy human subjects, demonstrates the feasibility of protease-activity-based liquid biopsies for early cancer diagnosis.

Core/shell iron/iron oxide nanoparticles: are they promising for magnetic hyperthermia?

Core/shell iron/iron oxide nanoparticles are promising for magnetic hyperthermia provided their size is big enough (>14 nm) in order to minimize surface disorder and hollowing effects that seriously deteriorate their heating efficiency.

Utilization of Enzyme-Immobilized Mesoporous Silica Nanocontainers (IBN-4) in Prodrug-Activated Cancer Theranostics

To develop a carrier for use in enzyme prodrug therapy, Horseradish peroxidase (HRP) was immobilized onto mesoporous silica nanoparticles (IBN-4: Institute of Bioengineering and Nanotechnology), where the nanoparticle surfaces were functionalized with 3-aminopropyltrimethoxysilane and further conjugated with glutaraldehyde. Consequently, the enzymes could be stabilized in nanochannels through the formation of covalent imine bonds. This strategy was used to protect HRP from immune exclusion, degradation and denaturation under biological conditions. Furthermore, immobilization of HRP in the nanochannels of IBN-4 nanomaterials exhibited good functional stability upon repetitive use and long-term storage (60 days) at 4 °C. The generation of functionalized and HRP-immobilized nanomaterials was further verified using various characterization techniques. The possibility of using HRP-encapsulated IBN-4 materials in prodrug cancer therapy was also demonstrated by evaluating their ability to convert a prodrug (indole-3- acetic acid (IAA)) into cytotoxic radicals, which triggered tumor cell apoptosis in human colon carcinoma (HT-29 cell line) cells. A lactate dehydrogenase (LDH) assay revealed that cells could be exposed to the IBN-4 nanocomposites without damaging their membranes, confirming apoptotic cell death. In summary, we demonstrated the potential of utilizing large porous mesoporous silica nanomaterials (IBN-4) as enzyme carriers for prodrug therapy.

SN-38 active loading in poly(lactic-co-glycolic acid) nanoparticles and assessment of their anticancer properties on COLO-205 human colon adenocarcinoma cells

SN-38 is a highly effective drug against many cancers. The development of an optimal delivery system for SN-38 is extremely challenging due to its low solubility and labile lactone ring. Herein, SN-38 encapsulated in poly(D,L-lactide-co-glycolide) nanoparticles (NPs) is introduced to enhance its solubility, stability and cellular uptake. SN-38-loaded NPs prepared by spontaneous emulsification solvent diffusion (SESD) method had an average diameter of 310 nm, a zeta potential of -9.69 mV and a loading efficiency of 71%. They were able to protect the active lactone ring of SN-38 against inactivation under physiological condition. A colorectal adenocarcinoma cell line (COLO-205) was used to assess the NPs effects on cytotoxicity and cellular uptake. Result showed a significant decreased cell proliferation and cell apoptosis. These results suggest that these SN-38-loaded NPs can be an effective delivery system for the treatment of colon cancer and potentially for other types of cancers.

Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe3O4 nanocomposites as a promising, nontoxic system for biomedical applications

The unique properties and applications of iron oxide and Au nanoparticles have motivated researchers to synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core-shell structures (such as reduced saturation magnetization and thick coating) have been overcome. In the present study, chitosan and one of its well-known derivatives, N-trimethylchitosan (TMC), were applied to construct three-layer nanocomposites in an Au/polymer/Fe3O4 system. It was demonstrated that replacement of chitosan with TMC reasonably improved the properties of the final nanocomposites including their size, magnetic behavior and thermal stability. Moreover, the results of the MTT assay showed no significant cytotoxicity effect when the Au/TMC/Fe3O4 nanocomposites were applied in vitro. These TMC-containing magnetic nanoparticles are well-coated by Au nanoparticles and have good biocompatibility and can thus play the role of a platform or a label in various fields of application, especially the biomedical sciences and biosensors.

Challenges in SN38 drug delivery: current success and future directions

INTRODUCTION

Clinical use of SN38 is limited by its poor aqueous solubility and hydrolysis of the lactone ring at pH > 6 to inactive carboxylate form. A variety of drug delivery systems have been developed to improve the solubility and stability of SN38, and reduce its toxicity. A few noteworthy formulations with some success in initial phases of clinical trials are reported.

AREAS COVERED

This work aims to provide a comprehensive review on the various techniques and strategies employed (physical, chemical and biological methods) to improve physicochemical properties and to deliver the drug efficiently to the cancer cells. Physical methods such as nanoparticle encapsulation, cyclodextrin complexation; chemical methods such as prodrugs, polymer-, albumin- and immunoconjugates; and enzyme activated prodrug therapy are discussed.

EXPERT OPINION

The challenges in SN38 drug delivery may be overcome by two ways: ensuring multiple layers of protection against degradation and slow but sustained release of therapeutically effective drug concentrations. It may also be achieved by preparing a polymer-drug conjugate and further encapsulating the conjugate in suitable carrier system; tumor-targeted SN38 delivery by using immunoconjugates, enzyme-activated prodrug therapy and antibody-directed nanoparticle delivery. However, selection of a suitable ligand for tumor targeting and use of safe and biocompatible nanoparticle systems play an important role in realizing this goal.

Macrophage mediated biomimetic delivery system for the treatment of lung metastasis of breast cancer

The biomimetic delivery system (BDS) based on special types of endogenous cells like macrophages and T cells, has been emerging as a novel strategy for cancer therapy, due to its tumor homing property and biocompatibility. However, its development is impeded by complicated construction, low drug loading or negative effect on the cell bioactivity. The present report constructed a BDS by loading doxorubicin (DOX) into a mouse macrophage-like cell line (RAW264.7). It was found that therapeutically meaningful amount of DOX could be loaded into the RAW264.7 cells by simply incubation, without significantly affecting the viability of the cells. Drug could release from the BDS and maintain its activity. RAW264.7 cells exhibited obvious tumor-tropic capacity towards 4T1 mouse breast cancer cells both in vitro and in vivo, and drug loading did not alter this tendency. Importantly, the DOX loaded macrophage system showed promising anti-cancer efficacy in terms of tumor suppression, life span prolongation and metastasis inhibition, with reduced toxicity. In conclusion, it is demonstrated that the BDS developed here seems to overcome some of the main issues related to a BDS. The DOX loaded macrophages might be a potential BDS for targeted cancer therapy.

Nested Helmholtz coil design for producing homogeneous transient rotating magnetic fields

Electromagnets that can produce strong rotating magnetic fields at kHz frequencies are potentially very useful to exert rotating force on magnetic nanoparticles as small as few nanometers in size. In this article, the construction of a pulsed high-voltage rotating electromagnet is demonstrated based on a nested Helmholtz coil design. The energy for the coils is provided by two high-voltage discharge capacitors. The triggered spark gaps used in the experiments show sufficient accuracy to achieve the high frequency rotating magnetic field. The measured strength of the rotating magnetic field is 200 mT. This magnetic field is scalable by increasing the number of turns on the coils, by reducing the dimensions of the coils and by increasing the discharge current/voltage of the capacitors.

Macrophages associated with tumors as potential targets and therapeutic intermediates

Tumor-associated macrophages (TAMs) form approximately 50% of tumor mass. TAMs were shown to promote tumor growth by suppressing immunocompetent cells, inducing neovascularization and supporting cancer stem cells. TAMs retain mobility in tumor mass, which can potentially be employed for better intratumoral biodistribution of nanocarriers and effective tumor growth inhibition. Due to the importance of TAMs, they are increasingly becoming principal targets of novel therapeutic approaches. In this review, we compare features of macrophages and TAMs that are essential for TAM-directed therapies, and illustrate the advantages of nanomedicine that are related to the preferential capture of nanocarriers by Mϕ in the process of drug delivery. We discuss recent efforts in reprogramming or inhibiting tumor-protecting properties of TAMs, and potential strategies to increase efficacy of conventional chemotherapy by combining with macrophage-associated delivery of nanodrugs.

Hexagonal magnetite nanoprisms: preparation, characterization and cellular uptake

Nearly perfect hexagonal Fe₃O₄ nanoplatelet structures, with edge length of 45 ± 5 nm and thickness of 5 to 6 nm were synthesized from iron(iii) acetylacetonate using the dual ligand system oleic and stearic acid.

Magnetic nanoparticle-based therapeutic agents for thermo-chemotherapy treatment of cancer

Magnetic nanoparticles have been widely investigated for their great potential as mediators of heat for localised hyperthermia therapy. Nanocarriers have also attracted increasing attention due to the possibility of delivering drugs at specific locations, therefore limiting systematic effects. The enhancement of the anti-cancer effect of chemotherapy with application of concurrent hyperthermia was noticed more than thirty years ago. However, combining magnetic nanoparticles with molecules of drugs in the same nanoformulation has only recently emerged as a promising tool for the application of hyperthermia with combined chemotherapy in the treatment of cancer. The main feature of this review is to present the recent advances in the development of multifunctional therapeutic nanosystems incorporating both magnetic nanoparticles and drugs, and their superior efficacy in treating cancer compared to either hyperthermia or chemotherapy as standalone therapies. The principle of magnetic fluid hyperthermia is also presented.

Sheet-type titania, but not P25, induced paraptosis accompanying apoptosis in murine alveolar macrophage cells

In this study, we identified the toxic effects of sheet-type titania (TNS), which are being developed as a material for UV-blocking glass, comparing with P25, a benchmark control for titania, in MH-S cells, a mouse alveolar macrophage cell line. After 24 h exposure, the TNS-exposed cells formed large vacuoles while the P25-exposed ones did not. The decreased levels of cell viability were similar between the P25 and TNS groups, but ATP production was clearly lower in cells exposed to the TNS. P25 decreased the expression of calnexin protein, an endoplasmic reticulum (ER) membrane marker, and increased the number of cells generating ROS in a dose dependent manner. Meanwhile, TNS dilated the ER and mitochondria and increased the secretion of NO and pro-inflammatory cytokines, but not of ROS. Subsequently, we studied the molecular response following TNS-induced vacuolization. TNS started to form vacuoles in the cytosol since 20 min after exposure, and the expression of the mitochondria function-related genes were down-regulated the most in the cells exposed for 1 h. After 24 h exposure, the number of apoptotic cells and the relative levels of BAX to Bcl-2 increased. The expression of SOD1 protein, but not of SOD2, also dose-dependently increased with an increase in caspase-8 activity. Additionally, the MAPK pathway was significantly activated, even though the expression of p-EGFR did not change significantly. Furthermore, the number of apoptotic cells increased rapidly with time and with the inhibition of vacuole formation. Taken together, we suggest that P25 and TNS may target different organelles. In addition, TNS, but not P25, induced paraptosis accompanied by apoptosis in MH-S cells, and the formation of the cytoplasmic vacuoles allowed delay apoptosis following TNS exposure.

Nanodiamond-DGEA peptide conjugates for enhanced delivery of doxorubicin to prostate cancer

The field of nanomedicine has emerged as an approach to enhance the specificity and efficacy of cancer treatments as stand-alone therapies and in combination with standard chemotherapeutic treatment regimens. The current standard of care for metastatic cancer, doxorubicin (DOX), is presented with challenges, namely toxicity due to a lack of specificity and targeted delivery. Nano-enabled targeted drug delivery systems can provide an avenue to overcome these issues. Nanodiamonds (ND), in particular, have been researched over the past five years for use in various drug delivery systems but minimal work has been done that incorporates targeting capability. In this study, a novel targeted drug delivery system for bone metastatic prostate cancer was developed, characterized, and evaluated in vitro. NDs were conjugated with the Asp-Gly-Glu-Ala (DGEA) peptide to target α2β1 integrins over-expressed in prostate cancers during metastasis. To facilitate drug delivery, DOX was adsorbed to the surface of the ND-DGEA conjugates. Successful preparation of the ND-DGEA conjugates and the ND-DGEA+DOX system was confirmed with transmission electron microscopy, hydrodynamic size, and zeta potential measurements. Since traditional DOX treatment regimens lack specificity and increased toxicity to normal tissues, the ND-DGEA conjugates were designed to distinguish between cells that overexpress α2β1 integrin, bone metastatic prostate cancers cells (PC3), and cells that do not, human mesenchymal stem cells (hMSC). Utilizing the ND-DGEA+DOX system, the efficacy of 1 µg/mL and 2 µg/mL DOX doses increased from 2.5% to 12% cell death and 11% to 34% cell death, respectively. These studies confirmed that the delivery and efficacy of DOX were enhanced by ND-DGEA conjugates. Thus, the targeted ND-DGEA+DOX system provides a novel approach for decreasing toxicity and drug doses.

Multifunctionalization of magnetic nanoparticles for controlled drug release: a general approach

In this study, a general approach for the multifunctionalization of magnetic nanoparticles (MNPs) with drugs (Doxorubicin and Gemcitabine) and targeting moieties (Nucant pseudopeptide) for controlled and selective release is described. The functionalization is achieved by the formation of disulfide bonds between MNPs and drugs derivatives synthesized in this work. Our strategy consists in the introduction of a pyridyldisulfide moiety to the drugs that react efficiently with sulfhydryl groups of pre-activated MNPs. This approach also allows the quantification of the covalently immobilized drug by measuring the amount of the 2-pyridinethione released during the process. The linkers developed here allow the release of drugs without any chemical modification. This process is triggered under highly reducing environment, such as that present inside the cells. Complete release of drugs is achieved within 5-8 h under intracellular conditions whereas negligible percentage of release is observed in extracellular conditions. We propose here a modular general approach for the functionalization of nanoparticles that can be used for different types of drugs and targeting agents.

Prodrug and nanomedicine approaches for the delivery of the camptothecin analogue SN38

SN38 (7-ethyl-10-hydroxy camptothecin) is a prominent and efficacious anticancer agent. It is poorly soluble in both water and pharmaceutically approved solvents; therefore, the direct formulation of SN38 in solution form is limited. Currently, the water soluble prodrug of SN38, irinotecan (CPT-11), is formulated as a low pH solution and is approved for chemotherapy. However, CPT-11, along with most other water-soluble prodrugs shows unpredictable inter-patient conversion to SN38 in vivo, instability in the physiological environment and variable dose-related toxicities. More recently, macromolecular prodrugs (i.e. EZN-2208, IMMU-130) and nanomedicine formulations (i.e. nanoemulsions, polymeric micelles, lipid nanocapsule/nanoparticle, and liposomes) of SN38 have been investigated for improved delivery to cancer cells and tissues. Specifically, these carriers can take advantage of the EPR effect to direct drug preferentially to tumour tissues, thereby substantially improving efficacy and minimising side effects. Furthermore, oral delivery has been shown to be possible in preclinical results using nanomedicine formulations (i.e. dendrimers, lipid nanocapsules, polymeric micelles). This review summarizes the recent advances for the delivery of SN38 with a focus on macromolecular prodrugs and nanomedicines.