Near-infrared light-triggered drug release from a multiple lipid carrier complex using an all-in-one strategy

Long-term combined blockade of CXCR4 and PD-L1 with in vivo reassembly for intensive tumor interference

Negative immunoregulatory signal (PD-L1, CXCR4, et al.) and weak immunogenicity elicited immune system failing to detect and destroy cancerous cells. CXCR4 blockade promoted T cell tumor infiltration and increased tumor sensitivity to anti-PD-L1 therapy. Here, pH-responsive reassembled nanomaterials were constructed with anti-PD-L1 peptide and CXCR4 antagonists grafting (APAB), synergized with photothermal therapy for melanoma and breast tumor interference. The self-assembled APAB nanoparticles accumulated in the tumor and rapidly transformed into nanofibers in response to the acidic tumor microenvironment, leading to the exposure of grafted therapeutic agents. APAB enabling to reassemble around tumor cells and remained stable for over 96 h due to the aggregation induced retention (AIR) effect, led to long-term efficiently combined PD-L1 and CXCR4 blockade. Photothermal efficiency (ICG) induced immunogenic cell death (ICD) of tumor cells so as to effectively improve the immunogenicity. The combined therapy (ICG@APAB) could effectively inhibit the growth of primary tumor (∼83.52%) and distant tumor (∼76.24%) in melanoma-bearing mice, and significantly (p < 0.05) prolong the survival time over 42 days. The inhibition assay on tumor metastasis in 4 T1 model mice exhibited ICG@APAB almostly suppressed the occurrence of lung metastases and the expression levels of CD31, MMP-9 and VEGF in tumor decreased by 82.26%, 90.45% and 41.54%, respectively. The in vivo reassembly strategy will offer novel perspectives benefical future immunotherapies and push development of combined therapeutics into clinical settings.

Light-Responsive and Dual-Targeting Liposomes: From Mechanisms to Targeting Strategies

In recent years, nanocarriers have played an ever-increasing role in clinical and biomedical applications owing to their unique physicochemical properties and surface functionalities. Lately, much effort has been directed towards the development of smart, stimuli-responsive nanocarriers that are capable of releasing their cargos in response to specific stimuli. These intelligent-responsive nanocarriers can be further surface-functionalized so as to achieve active tumor targeting in a sequential manner, which can be simply modulated by the stimuli. By applying this methodological approach, these intelligent-responsive nanocarriers can be directed to different target-specific organs, tissues, or cells and exhibit on-demand controlled drug release that may enhance therapeutic effectiveness and reduce systemic toxicity. Light, an external stimulus, is one of the most promising triggers for use in nanomedicine to stimulate on-demand drug release from nanocarriers. Light-triggered drug release can be achieved through light irradiation at different wavelengths, either in the UV, visible, or even NIR region, depending on the photophysical properties of the photo-responsive molecule embedded in the nanocarrier system, the structural characteristics, and the material composition of the nanocarrier system. In this review, we highlighted the emerging functional role of light in nanocarriers, with an emphasis on light-responsive liposomes and dual-targeted stimuli-responsive liposomes. Moreover, we provided the most up-to-date photo-triggered targeting strategies and mechanisms of light-triggered drug release from liposomes and NIR-responsive nanocarriers. Lastly, we addressed the current challenges, advances, and future perspectives for the deployment of light-responsive liposomes in targeted drug delivery and therapy.

Biomaterials-enhanced bioactive agents to efficiently block spinal metastases of cancers

The spine is the most common site of bone metastases, as 20%-40% of cancer patients suffer from spinal metastases. Treatments for spinal metastases are scarce and palliative, primarily aiming at relieving bone pain and preserving neurological function. The bioactive agents-mediated therapies are the most effective modalities for treating spinal metastases because they achieve systematic and specific tumor regression. However, the clinical applications of some bioactive agents are limited due to the lack of targeting capabilities, severe side effects, and vulnerability of drug resistance. Fortunately, advanced biomaterials have been developed as excipients to enhance these treatments, including chemotherapy, phototherapy, magnetic hyperthermia therapy, and combination therapy, by improving tumor targeting and enabling sustaining and stimuli-responsive release of various therapeutic agents. Herein, the review summarizes the development of biomaterials-mediated bioactive agents for enhanced treatments of spinal metastases and predicts future research trends.

In vivo deep-brain 2-photon fluorescent microscopy labeled with near-infrared dyes excited at the 1700 nm window

2-Photon fluorescence microscopy (2PFM) is an indispensable imaging technology for neuroscience. However, the imaging depth is usually limited to the cortical layer in mouse brain in vivo. Here, we demonstrate deep brain 2PFM in vivo excited at the 1700 nm window, using IR780 and aza-IR780 as fluorescent labels. Our detailed characterization of the multiphoton excitation and emission properties of IR780 and aza-IR780 show that: (1) IR780 or aza-IR780 generate 2-photon fluorescence excited at the 1700 nm window and are promising for 2PFM; (2) aza-IR780 exhibits a larger ησ₂ with better anti-photobleaching property compared to IR780; The 2-photon action cross-sections of IR780 and aza-IR780 in plasma are an order-of-magnitude larger than those in PBS; (3) In vivo 2-photon emission spectra for both dyes show a notable red shift compared to those in vitro. Based on these characterization results, we demonstrate deep brain 2PFM labeled by them. A maximum imaging depth of 1585 μm (labeled by IR780) and 1800 μm (labeled by aza-IR780) into the mouse brain in vivo readily penetrates the subcortical region of hippocampus. Besides, a maximum of 1528 μm hemodynamic imaging depth is realized via 2PFM with aza-IR780 labeling, enabling us to measure blood flow speed in the hippocampus.

Coarse-Grained Molecular Dynamics of pH-Sensitive Lipids

pH-sensitive lipids represent a class of lipids that can be protonated and destabilized in acidic environments, as they become positively charged in response to low-pH conditions. They can be incorporated into lipidic nanoparticles such as liposomes, which are able to change their properties and allow specific drug delivery at the acidic conditions encountered in some pathological microenvironments. In this work, we used coarse-grained molecular-dynamic simulations to study the stability of neutral and charged lipid bilayers containing POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and various kinds of ISUCA ((F)2-(imidazol-1-yl)succinic acid)-derived lipids, which can act as pH-sensitive molecules. In order to explore such systems, we used a MARTINI-derived forcefield, previously parameterized using all-atom simulation results. We calculated the average area per lipid, the second-rank order parameter and the lipid diffusion coefficient of both lipid bilayers made of pure components and mixtures of lipids in different proportions, under neutral or acidic conditions. The results show that the use of ISUCA-derived lipids disturbs the lipid bilayer structure, with the effect being particularly marked under acidic conditions. Although more-in depth studies on these systems must be carried out, these initial results are encouraging and the lipids designed in this research could be a good basis for developing new pH-sensitive liposomes.

Photothermal Properties of IR-780-Based Nanoparticles Depend on Nanocarrier Design: A Comparative Study on Synthetic Liposomes and Cell Membrane and Hybrid Biomimetic Vesicles

Biomimetic nanoparticles hold great promise for photonic-mediated nanomedicine due to the association of the biological functionality of the membrane with the physical/chemical goals of organic/inorganic structures, but studies involving fluorescent biomimetic vesicles are still scarce. The purpose of this article is to determine how photothermal therapy (PTT) with theranostic IR-780-based nanoparticles depends on the dye content, cholesterol content, lipid bilayer phase and cell membrane type. The photophysical responses of synthetic liposomes, cell membrane vesicles and hybrid nanoparticles are compared. The samples were characterized by nanoparticle tracking analysis, photoluminescence, electron spin resonance, and photothermal- and heat-mediated drug release experiments, among other techniques. The photothermal conversion efficiency (PCE) was determined using Roper's method. All samples excited at 804 nm showed three fluorescence bands, two of them independent of the IR-780 content. Samples with a fluorescence band at around 850 nm showed photobleaching (PBL). Quenching was higher in cell membrane vesicles, while cholesterol inhibited quenching in synthetic liposomes with low dye content. PTT depended on the cell membrane and was more efficient for melanoma than erythrocyte vesicles. Synthetic liposomes containing cholesterol and a high amount of IR-780 presented superior performance in PTT experiments, with a 2.4-fold PCE increase in comparison with free IR-780, no PBL and the ability to heat-trigger doxorubicin release.

VB12-Sericin-PBLG-IR780 Nanomicelles for Programming Cell Pyroptosis via Photothermal (PTT)/Photodynamic (PDT) Effect-Induced Mitochondrial DNA (mitoDNA) Oxidative Damage

Pyroptosis, a kind of programmed cell death involving inflammation, might be a powerful way to fight against tumors, for example, using immunotherapy. However, how to trigger pyroptosis in cancer cells is an important issue. Photothermal (PTT)/photodynamic (PDT) therapy is a crucial strategy for inducing cancer cell pyroptosis with noninvasiveness. In this work, a sericin derivative modified with poly(γ-benzyl-l-glutamate) (PBLG) could self-assemble and was stable in an aqueous environment. Furthermore, the sericin derivative was conjugated with the tumor-targeting agent VB12 and loaded with IR780. Finally, we successfully synthesized VB12-sericin-PBLG-IR780 nanomicelles. The as-designed nanomicelles showed appropriate particle sizes, spherical morphology, improved photothermal stability, and high photothermal conversion efficiency (∼40%), which generated reactive oxygen species (ROS) simultaneously. Through enhanced cellular uptake, VB12-sericin-PBLG-IR780 could deliver more IR780 into cancer cells. With near-infrared (NIR), the VB12-sericin-PBLG-IR780 could significantly inhibit the expression of ATP synthase, called ATP5MC3, followed by mitochondrial damage. The presence of mitochondrial reactive oxygen species (mitoROS) led to oxidative damage of mitochondrial DNA (mitoDNA), which further activates NLRP3/Caspase-1/gasdermin D (GSDMD)-dependent pyroptosis and could promote dendritic cell (DC) maturation by pyroptosis. Furthermore, our data showed that VB12-sericin-PBLG-IR780 could achieve a brilliant antitumor effect and could activate DC maturation, initiate T-cell recruiting, and prime adaptive antitumor efficiency. Overall, our well-prepared nanomicelles might offer a tumor-targeted approach for programmed cell pyroptosis and inducing antitumor immunity via photothermal PTT/PDT effect-induced mitoDNA oxidative damage.

Photoactive "Bionic Virus" Robustly Elicits the Synergy Anticancer Activity of Immunophotodynamic Therapy

Coronavirus represents an inspiring model for designing drug delivery systems due to its unique infection machinery mechanism. Herein, we have developed a biomimetic viruslike nanocomplex, termed SDN, for improving cancer theranostics. SDN has a unique core-shell structure consisting of photosensitizer chlorin e6 (Ce6)-loaded nanostructured lipid carrier (CeNLC) (virus core)@poly(allylamine hydrochloride)-functionalized MnO₂ nanoparticles (virus spike), generating a virus-mimicking nanocomplex. SDN not only prompted cellular uptake through rough-surface-mediated endocytosis but also achieved mitochondrial accumulation by the interaction of cationic spikes and the anionic mitochondrial surface, leading to mitochondria-specific photodynamic therapy. Meanwhile, SDN could even mediate oxygen generation to relieve tumor hypoxia and, consequently, improve macrophage-associated anticancer immune response. Importantly, SDN served as a robust magnetic resonance imaging (MRI) contrast agent due to the fast release of Mn²⁺ in the presence of intracellular redox components. We identified that SDN selectively accumulated in tumors and released Mn²⁺ to generate a 5.71-fold higher T₁-MRI signal, allowing for effectively detecting suspected tumors. Particularly, SDN induced synergistic immunophotodynamic effects to eliminate malignant tumors with minimal adverse effects. Therefore, we present a novel biomimetic strategy for improving targeted theranostics, which has a wide range of potential biomedical applications.

A hypoxia-responsive supramolecular formulation for imaging-guided photothermal therapy

Photothermal agents (PTAs) based on organic small-molecule dyes emerge as promising theranostic strategy in imaging and photothermal therapy (PTT). However, hydrophobicity, photodegradation, and low signal-to-noise ratio impede their transformation from bench to bedside. In this study, a novel supramolecular PTT formulation by a stimuli-responsive macrocyclic host is prepared to overcome these obstacles of organic small-molecule PTAs. Methods: Sulfonated azocalix[4]arene (SAC4A) was synthesized as a hypoxia-responsive macrocyclic host. Taking IR780 as an example, the supramolecular nanoformulation IR780@SAC4A was constructed by grinding method, and its solubility, photostability, and photothermal conversion were evaluated. The hypoxia tumor-selective imaging and supramolecular PTT of IR780@SAC4A were further evaluated in vitro and in vivo. Results: IR780@SAC4A is capable of enhancing the solubility, photostability, and photothermal conversion of IR780 significantly, which achieve this supramolecular formulation with good imaging-guided PTT efficacy in vitro and in vivo. Conclusions: This study demonstrates that the supramolecular PTT strategy is a promising cancer theranostic method. Moreover, this supramolecular approach is applicative to construct kinds of supramolecular PTAs, opening a general avenue for extending smart PTT formulations.

Strategies for Liposome Drug Delivery Systems to Improve Tumor Treatment Efficacy

In the advancement of tumor therapy, in addition to the search for new antitumor compounds, the development of nano-drug delivery systems has opened up new pathways for tumor treatment by addressing some of the limitations of traditional drugs. Liposomes have received much attention for their high biocompatibility, low toxicity, high inclusivity, and improved drug bioavailability. They are one of the most studied nanocarriers, changing the size and surface characteristics of liposomes to better fit the tumor environment by taking advantage of the unique pathophysiology of tumors. They can also be designed as tumor targeting drug delivery vehicles for the precise delivery of active drugs into tumor cells. This paper reviews the current development of liposome formulations, summarizes the characterization methods of liposomes, and proposes strategies to improve the effectiveness of tumor treatment. Finally, it provides an outlook on the challenges and future directions of the field. Graphical abstract.

Precision biomaterials in cancer theranostics and modelling

Despite significant achievements in the understanding and treatment of cancer, it remains a major burden. Traditional therapeutic approaches based on the 'one-size-fits-all' paradigm are becoming obsolete, as demonstrated by the increasing number of patients failing to respond to treatments. In contrast, more precise approaches based on individualized genetic profiling of tumors have already demonstrated their potential. However, even more personalized treatments display shortcomings mainly associated with systemic delivery, such as low local drug efficacy or specificity. A large amount of effort is currently being invested in developing precision medicine-based strategies for improving the efficiency of cancer theranostics and modelling, which are envisioned to be more accurate, standardized, localized, and less expensive. To this end, interdisciplinary research fields, such as biomedicine, material sciences, pharmacology, chemistry, tissue engineering, and nanotechnology, must converge for boosting the precision cancer ecosystem. In this regard, precision biomaterials have emerged as a promising strategy to detect, model, and treat cancer more efficiently. These are defined as those biomaterials precisely engineered with specific theranostic functions and bioactive components, with the possibility to be tailored to the cancer patient needs, thus having a vast potential in the increasing demand for more efficient treatments. In this review, we discuss the latest advances in the field of precision biomaterials in cancer research, which are expected to revolutionize disease management, focusing on their uses for cancer modelling, detection, and therapeutic applications. We finally comment on the needed requirements to accelerate their application in the clinic to improve cancer patient prognosis.

Lipid Nanoparticles─From Liposomes to mRNA Vaccine Delivery, a Landscape of Research Diversity and Advancement

Lipid nanoparticles (LNPs) have emerged across the pharmaceutical industry as promising vehicles to deliver a variety of therapeutics. Currently in the spotlight as vital components of the COVID-19 mRNA vaccines, LNPs play a key role in effectively protecting and transporting mRNA to cells. Liposomes, an early version of LNPs, are a versatile nanomedicine delivery platform. A number of liposomal drugs have been approved and applied to medical practice. Subsequent generations of lipid nanocarriers, such as solid lipid nanoparticles, nanostructured lipid carriers, and cationic lipid-nucleic acid complexes, exhibit more complex architectures and enhanced physical stabilities. With their ability to encapsulate and deliver therapeutics to specific locations within the body and to release their contents at a desired time, LNPs provide a valuable platform for treatment of a variety of diseases. Here, we present a landscape of LNP-related scientific publications, including patents and journal articles, based on analysis of the CAS Content Collection, the largest human-curated collection of published scientific knowledge. Rising trends are identified, such as nanostructured lipid carriers and solid lipid nanoparticles becoming the preferred platforms for numerous formulations. Recent advancements in LNP formulations as drug delivery platforms, such as antitumor and nucleic acid therapeutics and vaccine delivery systems, are discussed. Challenges and growth opportunities are also evaluated in other areas, such as medical imaging, cosmetics, nutrition, and agrochemicals. This report is intended to serve as a useful resource for those interested in LNP nanotechnologies, their applications, and the global research effort for their development.

IR780-based nanomaterials for cancer imaging and therapy

IR780, a small molecule with a strong optical property and excellent photoconversion efficiency following near infrared (NIR) irradiation, has attracted increasing attention in the field of cancer treatment and imaging. This review is focused on different IR780-based nanoplatforms and the application of IR780-based nanomaterials for cancer bioimaging and therapy. Thus, this review summarizes the overall aspects of IR780-based nanomaterials that positively impact cancer biomedical applications.

Stimuli-Responsive Nanomaterials for Application in Antitumor Therapy and Drug Delivery

The new era of nanotechnology has produced advanced nanomaterials applicable to various fields of medicine, including diagnostic bio-imaging, chemotherapy, targeted drug delivery, and biosensors. Various materials are formed into nanoparticles, such as gold nanomaterials, carbon quantum dots, and liposomes. The nanomaterials have been functionalized and widely used because they are biocompatible and easy to design and prepare. This review mainly focuses on nanomaterials responsive to the external stimuli used in drug-delivery systems. To overcome the drawbacks of conventional therapeutics to a tumor, the dual- and multi-responsive behaviors of nanoparticles have been harnessed to improve efficiency from a drug delivery point of view. Issues and future research related to these nanomaterial-based stimuli sensitivities and the scope of stimuli-responsive systems for nanomedicine applications are discussed.

Controlled Release of Doxorubicin from the Drug Delivery Formulation Composed of Single-Walled Carbon Nanotubes and Congo Red: A Molecular Dynamics Study and Dynamic Light Scattering Analysis

The controlled delivery and release of drug molecules at specific targets increases the therapeutic efficacy of treatment. This paper presents a triple complex which is a new potential drug delivery system. Triple complex contains single-walled carbon nanotubes, Congo red, and doxorubicin. Nanotubes are built of a folded graphene layer providing a large surface for binding Congo red via “face-to-face” stacking which markedly increases the binding capacity of the carrier. Congo red is a compound that self-associates to form supramolecular ribbon-like structures, which are able to bind some drugs by intercalation. The nanotube–Congo red complex can bind the model drug doxorubicin. Thus, a new triple carrier system was obtained. The aim of this paper is to present studies on the controlled release of a model anticancer drug from a triple carrier system through pH changes. The specific aim of the study was to model the structure of the obtained experimental systems and to compare the changes in the average energy of interaction between its components induced by pH changes. The studies also aimed to compare the intensity of pH-dependent changes in hydrodynamic diameters of individual components of the triple carrier system. The effect of pH changes on the stability of the analyzed systems was examined using the molecular modeling method and dynamic light scattering. The decrease in pH influenced the structure and stability of the analyzed triple systems and ensured efficient drug release. The changes in hydrodynamic diameters of the obtained fractions were examined with the use of dynamic light scattering and were confirmed by computer simulation methods. The formulation presented in this paper shows potential for a therapeutic application owing to its high drug binding capacity and pH-dependent release. This ensures prolonged local action of the drug. The results reveal that the studied complex fulfills the basic requirements for its potential use as drug carrier, thus reducing side effects and enhancing pharmacological efficacy of drugs.

Stimuli-Responsive Polymeric Nanocarriers for Drug Delivery, Imaging, and Theragnosis

In the past few decades, polymeric nanocarriers have been recognized as promising tools and have gained attention from researchers for their potential to efficiently deliver bioactive compounds, including drugs, proteins, genes, nucleic acids, etc., in pharmaceutical and biomedical applications. Remarkably, these polymeric nanocarriers could be further modified as stimuli-responsive systems based on the mechanism of triggered release, i.e., response to a specific stimulus, either endogenous (pH, enzymes, temperature, redox values, hypoxia, glucose levels) or exogenous (light, magnetism, ultrasound, electrical pulses) for the effective biodistribution and controlled release of drugs or genes at specific sites. Various nanoparticles (NPs) have been functionalized and used as templates for imaging systems in the form of metallic NPs, dendrimers, polymeric NPs, quantum dots, and liposomes. The use of polymeric nanocarriers for imaging and to deliver active compounds has attracted considerable interest in various cancer therapy fields. So-called smart nanopolymer systems are built to respond to certain stimuli such as temperature, pH, light intensity and wavelength, and electrical, magnetic and ultrasonic fields. Many imaging techniques have been explored including optical imaging, magnetic resonance imaging (MRI), nuclear imaging, ultrasound, photoacoustic imaging (PAI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). This review reports on the most recent developments in imaging methods by analyzing examples of smart nanopolymers that can be imaged using one or more imaging techniques. Unique features, including nontoxicity, water solubility, biocompatibility, and the presence of multiple functional groups, designate polymeric nanocues as attractive nanomedicine candidates. In this context, we summarize various classes of multifunctional, polymeric, nano-sized formulations such as liposomes, micelles, nanogels, and dendrimers.

Stimuli-responsive nanocarriers for drug delivery, tumor imaging, therapy and theranostics

In recent years, much progress has been motivated in stimuli-responsive nanocarriers, which could response to the intrinsic physicochemical and pathological factors in diseased regions to increase the specificity of drug delivery. Currently, numerous nanocarriers have been engineered with physicochemical changes in responding to external stimuli, such as ultrasound, thermal, light and magnetic field, as well as internal stimuli, including pH, redox potential, hypoxia and enzyme, etc. Nanocarriers could respond to stimuli in tumor microenvironments or inside cancer cells for on-demanded drug delivery and accumulation, controlled drug release, activation of bioactive compounds, probes and targeting ligands, as well as size, charge and conformation conversion, etc., leading to sensing and signaling, overcoming multidrug resistance, accurate diagnosis and precision therapy. This review has summarized the general strategies of developing stimuli-responsive nanocarriers and recent advances, presented their applications in drug delivery, tumor imaging, therapy and theranostics, illustrated the progress of clinical translation and made prospects.

Prototypic Heptamethine Cyanine Incorporating Nanomaterials for Cancer Phototheragnostic

Developing technologies that allow the simultaneous diagnosis and treatment of cancer (theragnostic) has been the quest of numerous interdisciplinary research teams. In this context, nanomaterials incorporating prototypic near infrared (NIR)-light responsive heptamethine cyanines have been showing very promising results for cancer theragnostic. The precisely engineered features of these nanomaterials endow them with the ability to achieve a high tumor accumulation, enabling a tumor's visualization by NIR fluorescence and photoacoustic imaging modalities. Upon interaction with NIR light, the tumor-homed heptamethine cyanine-incorporating nanomaterials can also produce a photothermal/photodynamic effect with a high spatio-temporal resolution and minimal side effects, leading to an improved therapeutic outcome. This progress report analyses the application of nanomaterials incorporating prototypic NIR-light responsive heptamethine cyanines (IR775, IR780, IR783, IR797, IR806, IR808, IR820, IR825, IRDye 800CW, and Cypate) for cancer photothermal therapy, photodynamic therapy, and imaging. Overall, the continuous development of nanomaterials incorporating the prototypic NIR absorbing heptamethine cyanines will cement their phototheragnostic capabilities.

A Multifunctional Lipid Incorporating Active Targeting and Dual-Control Release Capabilities for Precision Drug Delivery

Active targeting and precise control of drug release based on nanoparticle therapies are urgently required to precisely treat cancer. We have custom-synthesized a functional lipid (termed Fa-ONB) by introducing a folic acid-targeting group into an o-nitro-benzyl ester lipid. As designed, the liposomes formed by Fa-ONB combine active targeting and dual trigger release capabilities, which help to improve drug efficacy and reduce the toxicity of traditional liposomes. We first verified that both pH-induced hydrolysis and light treatment were able to cleave the Fa-ONB lipid. We then prepared a series of liposomes (termed FOBD liposomes) by compounding the Fa-ONB lipid with DOPC at different ratios. After encapsulation of doxorubicin (DOX), we found that the particle size of DOX-loaded FOBD liposomes (DOX/FOBD) first increased (290 to 700 nm) and then decreased again (to 400 nm) under continuous UV irradiation (120 min). The photocatalytic release efficiency under different pH conditions was investigated by dialysis experiments, and it was found that the release efficiency in an acidic environment was significantly increased relative to neutral pH. This pH-triggered release response helps distinguish pathological tissues such as lysosomal compartments and tumors. The light-induced formation of a DOX precipitate increases in efficiency with increasing UV exposure time as well as with increasing environmental acidity or alkalinity. In addition, confocal imaging and flow cytometry showed that the ability of FOBD lipids to actively target HeLa cells increased with increasing Fa-ONB lipid content. Real-time in vivo fluorescence small animal experiments proved targeting to tumors and pH- and photo-induced release properties. Furthermore, therapeutic experiments using a mouse model found a significant tumor inhibitory effect for DOX/FOBD55 liposomes with UV irradiation, clearly demonstrating the benefit of light treatment: the tumor size of the control (PBS) group was 7.59 times that of the light treatment group. Therefore, this research demonstrates the benefits of combining triggerable release functions and effective active tumor targeting in one small lipid molecule for precise cancer treatment.

Stimuli-responsive polymeric prodrug-based nanomedicine delivering nifuroxazide and doxorubicin against primary breast cancer and pulmonary metastasis

Functionalized drug delivery systems against malignant lung metastasis of breast cancer have been extensively studied, while metastasis remains a challenging issue. We propose a new strategy to achieve eradication of primary breast cancer cells and inhibition of pulmonary metastasis. A cathepsin B/pH dual-sensitive block copolymer with a molecular weight of 92 kDa was synthesized to conjugate with doxorubicin (DOX). The copolymer-DOX was further loaded with nifuroxazide (NFX) to self-assemble co-prodrug-loaded micelles (CLM). CLM displayed a drug release pattern in response to pH/enzyme dual stimuli and was enzymatically biodegradable. CLM was demonstrated to reduce viability and inhibit migration and invasion of 4T1 murine breast cancer cells in vitro. After i.v. injection of CLM, its nanoscale size and stimuli-responsiveness facilitated delivery of drugs to the tumor site in mice. Enhanced anti-tumor efficacy and great anti-metastatic effects were found in both orthotropic and lung metastasis 4T1 breast cancer mice models. Meanwhile, histological immunofluorescence and immunohistochemical analyses revealed a high level of apoptosis, suppressed expression of matrix metalloproteinases and reduction in MDSCs infiltration, and all these contributed to inhibit pulmonary metastasis. CLM may be explored as a potential nanomedicine against breast cancer metastasis.

A nanoscale photothermal agent based on a metal-organic coordination polymer as a drug-loading framework for effective combination therapy

Metallic materials are widely emerging as photothermal agents owing to their superior photothermal transduction efficiency and satisfactory photostability. In this study, an iron-based coordination polymer (Fe-CNP) loaded with doxorubicin (DOX) was assessed as a dual-function agent for photothermal therapy (PTT) and tumor-targeted chemotherapy. Fe-CNPs were synthesized by a one-step coordination reaction between Fe³⁺, hydrocaffeic acid, and dopamine-modified hyaluronic acid. A drug-loading method was developed to entrap DOX within Fe-CNPs through the formation of coordination bonds by Fe³⁺ and DOX (Scheme 1). DOX release was rapidly triggered in the cellular acidic environment and further enhanced by hyperpyrexia in the part of tumor, which will kill the remaining tumor cells after PTT. Animal experiments demonstrated complete inhibition of tumor growth without recurrence in 21 days after injection of DOX@Fe-CNPs with NIR laser irradiation. These results confirmed the enhanced anti-tumor efficiency of the chemo-photothermal nanosystem. Our work may reveal a photothermal coordination polymer as a drug-loading framework and highlight the development of metal-organic materials in combined chemo-photothermal therapy. STATEMENT OF SIGNIFICANCE: Photothermal therapy (PTT), which could directly act on tumors, has been considered as a promising treatment method for cancer. The combination of PTT with chemotherapy is attracting tremendous attention because such advanced application can achieve personalized precise medicine. Unfortunately, most PTT materials have photobleaching property, which results in reduced photothermal efficiency. Furthermore, their clinical applications also suffer from low loading capacity of chemotherapeutic drugs or nonbiodegradability in the biological system. In this study, we hypothesized that iron-based coordination polymers (Fe-CNPs) could function dually as agents to deliver both PTT and tumor-targeted chemotherapy by coordination loading of the chemotherapeutic drug doxorubicin (DOX). Our work may open up new avenues to rationally design versatile platforms for photothermal-chemotherapy to obtain synergistically enhanced therapeutic efficacy.

Mathematical modeling of the heterogeneous distributions of nanomedicines in solid tumors

The distribution of nanomedicines inside solid tumors is often restricted to perivascular areas, leaving most distal tumor cells out of reach. This partly explains modest patient benefit of many nanomedicines compared to their free-form counterparts. The objective for this study is to develop a mathematical model to quantitatively analyze this phenomenon and the influencing factors to such perivascular distribution and seek for effective strategies to alleviate this. A spatial tumor distribution model was firstly constructed to mimic the geometrical structure of tumor vessels and the surrounding tumor cells. This tumor model was further integrated with a systemic pharmacokinetics model for nanoparticles. A variety of factors on the tumor spatial distributions of nanomedicines were considered in the model. With the model, we quantified the effect of these influencing factors on tumor delivery efficacy (ID %), the magnitude of heterogeneous distribution (H index), and the effect of enhanced permeability and retention (EPR). In particularly, we compared the spatial distributions of the nanoparticles and the free payloads insides tumors. The model predicted high degrees of distributional heterogeneity for both nanoparticles and free payloads. The degree of heterogeneity and the influencing factors for free payloads were markedly different from those for nanoparticles. We found that nanoparticle diffusion coefficient was the most effective factor in reducing the nanoparticle H index but exerted moderate influence on the free payloads H index. The most effective factor in reducing the H index of free payload was payload diffusion coefficient. The factors that improved free payload distribution were closely associated with higher drug efficacy. In contrast, the factors that improved nanoparticle spatial distributions did not always confer improved anti-tumor efficacy of the delivered drug. These findings highlight the importance of assessing the heterogeneous free payload distribution in tumors for the development of effective nanomedicines.

IR780-based light-responsive nanocomplexes combining phase transition for enhancing multimodal imaging-guided photothermal therapy

Near-infrared (NIR) light-triggered photothermal therapy (PTT) has been widely applied for treating cancer. The combination of nanotechnology and NIR has shown great promise for promoting the efficacy of PTT. However, PTT alone could not completely ablate the tumors and easily causes tumor recurrence. To overcome this challenge, many studies have been performed to enhance PTT, including combining chemical therapy and radiotherapy, both of which have side effects on the body. To reduce the side effects and enhance PTT, a new infrared IR780-based nanocomplex combining liquid fluorocarbon perfluoropentane (PFP) has been synthesized for enhancing multimodal imaging-guided PTT. Under NIR irradiation, the size changes of PFP-loaded nanobubbles transforming into microbubbles allow ultrasound (US) imaging, showing boundaries and internal information of tumors. The breakup process and cascade reaction of phase transition can improve intratumoral permeation and retention of nanoparticles in nonmicrovascular tissue and damage the cell membranes of tumors, further enhancing PTT to kill tumor cells. The strong absorption in the NIR field of IR780-loaded NPs allows not only photoacoustic (PA) imaging but also NIR fluorescence (NIRF) imaging, which provides more anatomical information about tumors. This nanocomplex exhibits good biocompatibility and nontoxicity, strong PA/US/NIRF imaging contrast, excellent liquid-gas transition and a photothermal effect. This finding provides a new method to enhance multimodal imaging-guided cancer nanotheranostics.

Hydrophobic IR780 loaded sericin nanomicelles for phototherapy with enhanced antitumor efficiency

The near-infrared dye, IR780 iodide, has been utilized in photodynamic therapy (PDT) and photothermal therapy (PTT). However, the hydrophobicity and photosensitivity of IR780 limit its further applications in biomedical fields. Herein, the hydrophilic sericin was modified with hydrophobic cholesterol to form an amphiphilic macromolecular conjugate (Ser-Chol). The tumor-targeting agent, folic acid (FA), was further linked to the conjugate (FA-Ser-Chol). The IR780 could be encapsulated into such amphiphilic macromolecule to form stable micelles (FA-Ser-Chol/IR780) by self-assembly, and the solubility and photo-stability of IR780 were greatly improved. The FA-Ser-Chol/IR780 micelles could be efficiently absorbed by FA-positive gastric cancer cells (BGC-823) through FA receptors, while the uptake micelles showed remarkable PDT and PTT cytotoxicity towards BGC-823 cells under laser irradiation of 808 nm. Therefore, FA-Ser-Chol micelles may serve as a promising IR780 carrier for PDT and PTT therapy.

IR780-loaded folate-targeted nanoparticles for near-infrared fluorescence image-guided surgery and photothermal therapy in ovarian cancer

Background and purpose: Surgery is regarded as the gold standard for patients with advanced ovarian cancer. However, complete surgical removal of tumors remains extremely challenging; fewer than 40% of patients are cured. Here, we developed a new modality of theranostics for ovarian cancer based on a near-infrared light-triggered nanoparticle. Methods: Nanoparticles loading IR780 iodide on base of folate modified liposomes were prepared and used for theranostics of ovarian cancer. Tumor targeting of FA-IR780-NP was evaluated in vitro and in an ovarian xenograft tumor model. A fluorescence stereomicroscope was applied to evaluate the tumor recognition of FA-IR780-NP during surgery. FA-IR780-NP mediated photothermal therapy effect was compared with other treatments in vivo. Results: FA-IR780-NP was demonstrated to specifically accumulate in tumors. IR780 iodide selectively accumulated in tumors; the enhanced permeability and retention effect of the nanoparticles and the active targeting of folate contributed to the excellent tumor targeting of FA-IR780-NP. With the aid of tumor targeting, FA-IR780-NP could be used as an indicator for the real-time delineation of tumor margins during surgery. Furthermore, photothermal therapy mediated by FA-IR780-NP effectively eradicated ovarian cancer tumors compared with other groups. Conclusion: In this study, we present a potential, effective approach for ovarian cancer treatment through near-infrared fluorescence image-guided resection and photothermal therapy to eliminate malignant tissue.

Endogenous and Exogenous Stimuli-Responsive Drug Delivery Systems for Programmed Site-Specific Release

In this study, we reviewed state-of-the-art endogenous-based and exogenous-based stimuli-responsive drug delivery systems (DDS) for programmed site-specific release to overcome the drawbacks of conventional therapeutic modalities. This particular work focuses on the smart chemistry and mechanism of action aspects of several types of stimuli-responsive polymeric carriers that play a crucial role in extracellular and intracellular sections of diseased tissues or cells. With ever increasing scientific knowledge and awareness, research is underway around the globe to design new types of stimuli (external/internal) responsive polymeric carriers for biotechnological applications at large and biomedical and/or pharmaceutical applications, in particular. Both external/internal and even dual/multi-responsive behavior of polymeric carriers is considered an essential element of engineering so-called 'smart' DDS, which controls the effective and efficient dose loading, sustained release, individual variability, and targeted permeability in a sophisticated manner. So far, an array of DDS has been proposed, developed, and implemented. For instance, redox, pH, temperature, photo/light, magnetic, ultrasound, and electrical responsive DDS and/or all in all dual/dual/multi-responsive DDS (combination or two or more from any of the above). Despite the massive advancement in DDS arena, there are still many challenging concerns that remain to be addressed to cover the research gap. In this context, herein, an effort has been made to highlight those concerning issues to cover up the literature gap. Thus, the emphasis was given to the drug release mechanism and applications of endogenous and exogenous based stimuli-responsive DDS in the clinical settings.

Multipronged design of theranostic nanovehicles with endogenous and exogenous stimuli-responsiveness for precise cancer therapy

Near-infrared (NIR) light-induced photothermal agent-based stimuli-responsive materials have attracted great interest from researchers. However, the highly smart release with precise control by NIR light is not yet well established because of the lack or inadequacy of intelligent release systems, such as premature release of drug and/or photothermal agent. Herein, we put forward a novel and convenient strategy to synthesize cyanine dye-functionalized polymeric materials, where cyanine dye was schemed to attach to polymeric materials by copolymerization, endowing the polymeric materials with NIR light-responsive photothermal property and fluorescent nature for real-time imaging of endocytosis and intracellular trafficking of nanovehicles. Meanwhile, the chemotherapy drug DOX was introduced into the cyanine-containing polymeric materials via formation of dynamic covalent hydrazone bond to circumvent the blood circulation barrier. The nanovehicles displayed fine pH/NIR light-controlled drug release and excellent tumor intracellular drug transposition, which were ulteriorly combined with photo-triggered hyperthermia for enhanced antitumor effect. Therefore, this multipronged design of theranostic nanovehicles with endogenous and exogenous stimuli-responsiveness provides a novel strategy to attain highly smart drug delivery for precise cancer therapy.

Near-infrared-induced IR780-loaded PLGA nanoparticles for photothermal therapy to treat breast cancer metastasis in bones

Nanodrug-based cancer therapy, especially when treating bone metastases, faces the problem of limited therapeutic efficacy. In this work, we reported a photothermally triggered nanomaterial based on IR780-entrapped poly-lactide-co-glycolide (PLGA) nanoparticles (IR780@PLGA NPs) for the photothermal therapy of bone metastases of breast cancer, in which IR780 converted light into heat to play a role in “burning” the tumors. Anti-tumor therapy studies showed the impressive effectiveness of IR780@PLGA NPs in the photothermal therapy (PTT) of bone metastases. As a result, the IR780@PLGA NPs show a great potential for controlling the bone metastases of breast cancer.

A schematic of PTT using IR780@PLGA NPs with NIR laser-controlled IR780 release.

A Promising Biocompatible Platform: Lipid-Based and Bio-Inspired Smart Drug Delivery Systems for Cancer Therapy

Designing new drug delivery systems (DDSs) for safer cancer therapy during pre-clinical and clinical applications still constitutes a considerable challenge, despite advances made in related fields. Lipid-based drug delivery systems (LBDDSs) have emerged as biocompatible candidates that overcome many biological obstacles. In particular, a combination of the merits of lipid carriers and functional polymers has maximized drug delivery efficiency. Functionalization of LBDDSs enables the accumulation of anti-cancer drugs at target destinations, which means they are more effective at controlled drug release in tumor microenvironments (TMEs). This review highlights the various types of ligands used to achieve tumor-specific delivery and discusses the strategies used to achieve the effective release of drugs in TMEs and not into healthy tissues. Moreover, innovative recent designs of LBDDSs are also described. These smart systems offer great potential for more advanced cancer therapies that address the challenges posed in this research area.

Tumor Microenvironment Targeted Nanotherapy

Recent developments in nanotechnology have brought new approaches to cancer diagnosis and therapy. While enhanced permeability and retention effect promotes nano-chemotherapeutics extravasation, the abnormal tumor vasculature, high interstitial pressure and dense stroma structure limit homogeneous intratumoral distribution of nano-chemotherapeutics and compromise their imaging and therapeutic effect. Moreover, heterogeneous distribution of nano-chemotherapeutics in non-tumor-stroma cells damages the non-tumor cells, and interferes with tumor-stroma crosstalk. This can lead not only to inhibition of tumor progression, but can also paradoxically induce acquired resistance and facilitate tumor cell proliferation and metastasis. Overall, the tumor microenvironment plays a vital role in regulating nano-chemotherapeutics distribution and their biological effects. In this review, the barriers in tumor microenvironment, its consequential effects on nano-chemotherapeutics, considerations to improve nano-chemotherapeutics delivery and combinatory strategies to overcome acquired resistance induced by tumor microenvironment have been summarized. The various strategies viz., nanotechnology based approach as well as ligand-mediated, redox-responsive, and enzyme-mediated based combinatorial nanoapproaches have been discussed in this review.

Delimiting the knowledge space and the design space of nanostructured lipid carriers through Artificial Intelligence tools

Nanostructured lipid carriers (NLC) are biocompatible and biodegradable nanoscale systems with extensive application for controlled drug release. However, the development of optimal nanosystems along with a reproducible manufacturing process is still challenging. In this study, a two-step experimental design was performed and databases were successfully modelled using Artificial Intelligence techniques as an innovative method to get optimal, reproducible and stable NLC. The initial approach, including a wide range of values for the different variables, was followed by a second set of experiments with variable values in a narrower range, more suited to the characteristics of the system. NLC loaded with rifabutin, a hydrophobic drug model, were produced by hot homogenization and fully characterized in terms of particle size, size distribution, zeta potential, encapsulation efficiency and drug loading. The use of Artificial Intelligence tools has allowed to elucidate the key parameters that modulate each formulation property. Stable nanoparticles with low sizes and polydispersions, negative zeta potentials and high drug loadings were obtained when the proportion of lipid components, drug, surfactants and stirring speed were optimized by FormRules^® and INForm^®. The successful application of Artificial Intelligence tools on NLC formulation optimization constitutes a pioneer approach in the field of lipid nanoparticles.

Charge and Assembly Reversible Micelles Fueled by Intracellular ATP for Improved siRNA Transfection

Hydrophobic modification on polycations were commonly used to improve the stability and transfection efficiency of polyplexes. However, the improved stability often means undesired release of the encapsulated siRNA, limiting the application of cationic micelles for siRNA delivery. The current strategy of preparing bioresponsive micelles based on the cleavage of sensitive linkages between polycation and hydrophobic part was far from sufficient, owing to the siRNA binding of the separated polycations from micelles leading to the incomplete release of siRNA. In this study, we propose a new strategy by the combination of micelles disassembly and separated polycations charge reversal. FPBA (3-fluoro-4-carboxyphenylboronic acid) grafted PEI 1.8 k (polyethylenimine) as the polycations of PEI-FPBA and dopamine (with diol-containing moiety) conjugated with cholesterol as the hydrophobic part (Chol-Dopa). The PFCDM micelles was assembled by PEI-FPBA and Chol-Dopa, based on the FPBA-Dopa conjugation. The prepared PFCDM showed strong siRNA loading ability and superior stability in the presence of PBS or serum. Besides, the PFCDM exhibited excellent ATP sensibility. The intracellular ATP could effectively trigger the disassembly of micelles and charge reversal of PEI-FPBA, resulting in the burst release of siRNA in the cytosol. With the property of extracellular stability and intracellular instability, PFCDM displayed good performance on in vitro and in vivo luciferase silencing on 4T1 cells. It should also be noted that the assembly of low molecular weight PEI was relatively safe to cells compared with 25 k PEI. To sum up, the ATP-fueled assembly and charge reversible micelles gave examples for polyplexes to achieve better stability and on demand cargo release at the same time and shows potential to be used for in vitro and in vivo siRNA transfection.

Near-Infrared Photoactivatable Nitric Oxide Donors with Integrated Photoacoustic Monitoring

Photoacoustic (PA) tomography is a noninvasive technology that utilizes near-infrared (NIR) excitation and ultrasonic detection to image biological tissue at centimeter depths. While several activatable small-molecule PA sensors have been developed for various analytes, the use of PA molecules for deep-tissue analyte delivery and monitoring remains an underexplored area of research. Herein, we describe the synthesis, characterization, and in vivo validation of photoNOD-1 and photoNOD-2, the first organic, NIR-photocontrolled nitric oxide (NO) donors that incorporate a PA readout of analyte release. These molecules consist of an aza-BODIPY dye appended with an aryl N-nitrosamine NO-donating moiety. The photoNODs exhibit chemostability to various biological stimuli, including redox-active metals and CYP450 enzymes, and demonstrate negligible cytotoxicity in the absence of irradiation. Upon single-photon NIR irradiation, photoNOD-1 and photoNOD-2 release NO as well as rNOD-1 or rNOD-2, PA-active products that enable ratiometric monitoring of NO release. Our in vitro studies show that, upon irradiation, photoNOD-1 and photoNOD-2 exhibit 46.6-fold and 21.5-fold ratiometric turn-ons, respectively. Moreover, unlike existing NIR NO donors, the photoNODs do not require encapsulation or multiphoton activation for use in live animals. In this study, we use PA tomography to monitor the local, irradiation-dependent release of NO from photoNOD-1 and photoNOD-2 in mice after subcutaneous treatment. In addition, we use a murine model for breast cancer to show that photoNOD-1 can selectively affect tumor growth rates in the presence of NIR light stimulation following systemic administration.

Tumor Oxygenation and Hypoxia Inducible Factor-1 Functional Inhibition via a Reactive Oxygen Species Responsive Nanoplatform for Enhancing Radiation Therapy and Abscopal Effects

Hypoxia, and hypoxia inducible factor-1 (HIF-1), can induce tumor resistance to radiation therapy. To overcome hypoxia-induced radiation resistance, recent studies have described nanosystems to improve tumor oxygenation for immobilizing DNA damage and simultaneously initiate oxygen-dependent HIF-1α degradation. However, HIF-1α degradation is incomplete during tumor oxygenation treatment alone. Therefore, tumor oxygenation combined with residual HIF-1 functional inhibition is crucial to optimizing therapeutic outcomes of radiotherapy. Here, a reactive oxygen species (ROS) responsive nanoplatform is reported to successfully add up tumor oxygenation and HIF-1 functional inhibition. This ROS responsive nanoplatform, based on manganese dioxide (MnO₂) nanoparticles, delivers the HIF-1 inhibitor acriflavine and other hydrophilic cationic drugs to tumor tissues. After reacting with overexpressed hydrogen peroxide (H₂O₂) within tumor tissues, Mn²⁺ and oxygen molecules are released for magnetic resonance imaging and tumor oxygenation, respectively. Cooperating with the HIF-1 functional inhibition, the expression of tumor invasion-related signaling molecules (VEGF, MMP-9) is obviously decreased to reduce the risk of metastasis. Furthermore, the nanoplatform could relieve T-cell exhaustion via downregulation of PD-L1, whose effects are similar to the checkpoint inhibitor PD-L1 antibody, and subsequently activates tumor-specific immune responses against abscopal tumors. These therapeutic benefits including increased X-ray-induced damage, downregulated resistance, and T-cell exhaustion related proteins expression achieved synergistically the optimal inhibition of tumor growth. Overall, this designed ROS responsive nanoplatform is of great potential in the sensitization of radiation for combating primary and metastatic tumors.

Near-Infrared-Light-Activatable Nanomaterial-Mediated Phototheranostic Nanomedicines: An Emerging Paradigm for Cancer Treatment

Cancer is one of the most deadly diseases threatening the lives of humans. Although many treatment methods have been developed to tackle cancer, each modality of cancer treatment has its own limitations and drawbacks. The development of minimally invasive treatment modalities for cancers remains a great challenge. Near-infrared (NIR) light-activated nanomaterial-mediated phototherapies, including photothermal and photodynamic therapies, provide an alternative means for spatially and temporally controlled minimally invasive treatments of cancers. Nanomaterials can serve as nanocargoes for the delivery of chemo-drugs, diagnostic contrast reagents, and organic photosensitizers, and can be used to directly generate heat or reactive oxygen species for the treatment of tumors without the need for organic photosensitizers with NIR-light irradiation. Here, current progress in NIR-light-activated nanomaterial-mediated photothermal therapy and photodynamic therapy is summarized. Furthermore, the effects of size, shape, and surface functionalities of nanomaterials on intracellular uptake, macrophage clearance, biodistribution, cytotoxicities, and biomedical efficacies are discussed. The use of various types of nanomaterials, such as gold nanoparticles, carbon nanotubes, graphene, and many other inorganic nanostructures, in combination with diagnostic and therapeutic modalities for solid tumors, is briefly reviewed.

Charge-switchable nanocapsules with multistage pH-responsive behaviours for enhanced tumour-targeted chemo/photodynamic therapy guided by NIR/MR imaging

Multifunctional nanoplatforms have been developed into advanced drug delivery systems for cancer therapy. In this study, we report a charge-switchable nanocapsule with multistage pH-responsive behaviors. First, DOX-encapsulated and oleylamine-embedded hollow structures with a diameter of 132 ± 21 nm are prepared via the double emulsion method. Subsequently, the hollow structures are encompassed by Gd-DTPA-, chlorin e6 (Ce6)-, and folate (FA)-modified BSA to form tumour-targeted, dual NIR/MR imaging-guided and chemo-photodynamic therapeutic nanoplatforms. Importantly, the nanocapsule can intelligently switch its surface charge to positive under mildly acidic conditions (pH 6.5) with no release of Ce6 and DOX, which is confirmed by ξ-potential and cumulative release measurements. Moreover, confocal imaging pictures demonstrate that acid-sensitive DOX sealed in nanocapsules is progressively released into the nuclei of MGC-803 cells. These advantages as well as FA-targeting facilitate effective endocytosis and synergistic therapeutic efficacy. Selective tumour accumulation and long tumour retention time are further indicated by NIR/MR in vivo imaging. In addition, excellent therapeutic efficacy combined with chemotherapy (DOX) and photodynamic therapy (PDT) is observed with the tumour eventually ablating at the 15th day. All results demonstrate that the as-prepared nanocapsules hold great potential for clinical cancer theranostics.

Promise of chemokine network-targeted nanoparticles in combination nucleic acid therapies of metastatic cancer

Chemokines and chemokine receptors play key roles in cancer progression and metastasis. Although multiple chemokines and chemokine receptors have been investigated, inhibition of CXCR4 emerged as one of the most promising approaches in combination cancer therapy, especially when focused on the metastatic disease. Small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), represent new class of therapeutics for cancer treatment through RNA interference-mediated gene silencing. However, the clinical applicability of siRNA and miRNA is severely limited by the lack of effective delivery systems. There is a significant therapeutic potential for CXCR4-targeted nanomedicines in combination with the delivery of siRNA and miRNA in cancer. Recently developed CXCR4-targeted polymeric drugs and nanomedicines, including cyclam- and chloroquine-based polymeric CXCR4 antagonists are introduced here and their ability to deliver functional siRNA and miRNA is discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Development of low molecular weight heparin based nanoparticles for metastatic breast cancer therapy

Tumor metastasis is the primary obstacle in cancer treatment and is always the leading cause of human death. And heparin and its derivatives are potential anti-metastatic agents with good biocompatibility. In this work, low molecular weight heparin (LMWH) based LMWH-Cholesterol (LHC) conjugates were prepared for intravenous delivery of doxorubicin (DOX). The DOX/LHC nanoparticles (DOX/LHC NPs) exhibited a spherical shape with a mean diameter of 135.5±2.2nm and had a longer circulation time than that of DOX. The in vitro results confirmed that the DOX/LHC NPs was more effectively taken up by 4T1 cells and showed a stronger anti-metastatic effect by cell invasion and cell migration compared with DOX. Meanwhile, DOX/LHC NPs also exhibited superior anti-metastatic effects in the pulmonary metastasis model compared with other groups. The reason may be account for the synergistic effect between the cytotoxic drug of DOX and its drug carrier of LMWH based nanoparticles, which is capable of anti-metastatic and anti-angiogenic efficiency. Thus DOX/LHC nanoparticles could be a promising anti-metastatic drug delivery system for postoperative chemotherapy.

Surface Functionalization and Targeting Strategies of Liposomes in Solid Tumor Therapy: A Review

Surface functionalization of liposomes can play a key role in overcoming the current limitations of nanocarriers to treat solid tumors, i.e., biological barriers and physiological factors. The phospholipid vesicles (liposomes) containing anticancer agents produce fewer side effects than non-liposomal anticancer formulations, and can effectively target the solid tumors. This article reviews information about the strategies for targeting of liposomes to solid tumors along with the possible targets in cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature. Targeting ligands for functionalization of liposomes with relevant surface engineering techniques have been described. Stimuli strategies for enhanced delivery of anticancer agents at requisite location using stimuli-responsive functionalized liposomes have been discussed. Recent approaches for enhanced delivery of anticancer agents at tumor site with relevant surface functionalization techniques have been reviewed. Finally, current challenges of functionalized liposomes and future perspective of smart functionalized liposomes have been discussed.

Low molecular weight heparin-based reduction-sensitive nanoparticles for antitumor and anti-metastasis of orthotopic breast cancer

Tumor metastasis has become a major obstacle for the clinical treatment of malignant breast cancer.