The Smart Drug Delivery System and Its Clinical Potential

Intracellular Distribution of Lipids and Encapsulated Model Drugs from Cationic Liposomes with Different Uptake Pathways

AIM

The uptake pathway of liposomes into cells is mainly via endocytosis or membrane fusion; however, the relationship between the uptake pathway and the intracellular pharmacokinetics of the liposome components remains unclear. This study aimed at revealing the relationship by using cationic liposomes having similar physical properties and different uptake pathways.

MATERIALS AND METHODS

We prepared cationic liposomes composed of amino acid-type lipids, K3C14 and K3C16, which have different uptake pathways by a hydration method, and fluorescently modified them by encapsulating FITC-dextran and surface conjugation with Alexa Fluor® 488 (AF488). Then, we investigated their intracellular distribution in HeLa cells over time.

RESULTS

The liposomes had similar physical properties and did not cause significant cell mortality after treatment for 180 min. The delivery rate and efficiency of encapsulated FITC-dextran with the fusogenic K3C16 liposomes were 3 and 1.6 times higher, respectively, than with the endocytic K3C14 liposomes. FITC-dextran molecules delivered with K3C16 liposomes were observed throughout the cytosolic space after 10 min, while those delivered with K3C14 liposomes were mainly observed as foci and took 60 min to diffuse into the cytosolic space. K3C14 lipids modified with AF488 were distributed mostly in the cytosolic space. In contrast, fluorescently labeled K3C16 lipids were colocalized with the plasma membrane of 50% of the HeLa cells after 10 min and were gradually internalized intracellularly.

CONCLUSION

Fusogenic K3C16 liposomes internalized into HeLa cells faster than endocytic K3C14 liposomes, and their components differently distributed in the cells.

Serum protein-based nanoparticles for cancer diagnosis and treatment

Serum protein as naturally essential biomacromolecules has recently emerged as a versatile carrier for diagnostic and therapeutic drug delivery for cancer nanomedicine with superior biocompatibility, improved pharmacokinetics and enhanced targeting capacity. A variety of serum proteins have been utilized for drug delivery, mainly including albumin, ferritin/apoferritin, transferrin, low-density lipoprotein, high-density lipoprotein and hemoglobin. As evidenced by the success of paclitaxel-bound albumin nanoparticles (Abraxane^TM), serum protein-based nanoparticles have gained attractive attentions for precise biological design and potential clinical application. In this review, we summarize the general design strategies, targeting mechanisms and recent development of serum protein-based nanoparticles in the field of cancer nanomedicine. Moreover, we also concisely specify the current challenges to be addressed for a bright future of serum protein-based nanomedicines.

Recent advances in applications of nanoparticles in SERS in vivo imaging

Surface-enhanced Raman scattering (SERS) technique has been regarded as one of the most important research methods in the field of single-molecule science. Since the previous decade, the application of nanoparticles for in vivo SERS imaging becomes the focus of research. To enhance the performance of SERS imaging, researchers have developed several SERS nanotags such as gold nanostars, copper-based nanomaterials, semiconducting quantum dots, and so on. The development of Raman equipment is also necessary owing to the current limitations. This review describes the recent advances of SERS nanoparticles and their applications for in vivo imaging in detail. Specific examples highlighting the in vivo cancer imaging and treatment application of SERS nanoparticles. A perspective on the challenges and opportunities of nanoparticles in SERS in vivo imaging is also provided. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Magnetite Nanoparticles and Spheres for Chemo- and Photothermal Therapy of Hepatocellular Carcinoma in vitro

Introduction

We present a multimodal nanoplatforms for the treatment of hepatocellular carcinoma (HCC) in vitro. The nanoplatforms are based on polydopamine (PDA)-coated magnetite nanoparticles (NPs) and spheres (sMAG) with PAMAM dendrimers and functionalized with NHS-PEG-Mal (N-hydroxysuccinimide–polyethylene glycol–maleimide) linker, which allows their functionalization with a folic acid derivative. The nanomaterials bearing a folic acid-targeting moiety show high efficiency in killing cancer cells in the dual chemo- and photothermal therapy (CT-PTT) of the liver cancer cells in comparison to modalities performed separately.

Materials and Methods

All materials are characterized in detail with transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential and magnetic measurements. Also, photothermal properties were determined under irradiation of nanoparticles with laser beam of 2 W/cm². The nontoxicity of nanoparticles with doxorubicin and without was checked by WST and LIVE/DEAD assay. Those tests were also used to evaluate materials bearing folic acid and anticancer drug in combined chemo- and photothermal therapy of HCC. Further, the generation of reactive oxygen species profile was also evaluated using flow cytometry test.

Results

Both NPs and sMAG showed high photothermal properties. Nevertheless, the higher photothermal response was found for magnetic spheres. Materials of concentration above 10 µg/mL reveal that their activity was comparable to free doxorubicin. It is worth highlighting that a functionalized magnetic sphere with DOXO more strongly affected the HepG2 cells than smaller functionalized nanoparticles with DOXO in the performed chemotherapy. This can be attributed to the larger size of particles and a different method of drug distribution. In the further stage, both materials were assessed in combined chemo- and photothermal therapy (CT-PTT) which revealed that magnetic spheres were also more effective in this modality than smaller nanoparticles.

Conclusion

Here, we present two types of nanomaterials (nanoparticles and spheres) based on polydopamine and PAMAM dendrimers g.5.0 functionalized with NHS-PEG-Mal linker terminated with folic acid for in vitro hepatocellular carcinoma treatment. The obtained materials can serve as efficient agents for dual chemo- and photothermal therapy of HCC. We also proved that PDA-coated magnetic spheres were more efficient in therapies based on near-infrared irradiation because determined cell viabilities for those materials are lower than for the same concentrations of nanomaterials based on small magnetic nanoparticles.

Chiral Cyclobutane-Containing Cell-Penetrating Peptides as Selective Vectors for Anti-Leishmania Drug Delivery Systems

Two series of new hybrid γ/γ-peptides, γ-CC and γ-CT, formed by (1S,2R)-3-amino-2,2,dimethylcyclobutane-1-carboxylic acid joined in alternation to a Nα-functionalized cis- or trans-γ-amino-l-proline derivative, respectively, have been synthesized and evaluated as cell penetrating peptides (CPP) and as selective vectors for anti-Leishmania drug delivery systems (DDS). They lacked cytotoxicity on the tumoral human cell line HeLa with a moderate cell-uptake on these cells. In contrast, both γ-CC and γ-CT tetradecamers were microbicidal on the protozoan parasite Leishmania beyond 25 μM, with significant intracellular accumulation. They were conjugated to fluorescent doxorubicin (Dox) as a standard drug showing toxicity beyond 1 μM, while free Dox was not toxic. Intracellular accumulation was 2.5 higher than with Dox-TAT conjugate (TAT = transactivator of transcription, taken as a standard CPP). The conformational structure of the conjugates was approached both by circular dichroism spectroscopy and molecular dynamics simulations. Altogether, computational calculations predict that the drug-γ-peptide conjugates adopt conformations that bury the Dox moiety into a cavity of the folded peptide, while the positively charged guanidinium groups face the solvent. The favorable charge/hydrophobicity balance in these CPP improves the solubility of Dox in aqueous media, as well as translocation across cell membranes, making them promising candidates for DDS.

Evaluation of Cytotoxic Effect of Cholesterol End-Capped Poly(N-Isopropylacrylamide)s on Selected Normal and Neoplastic Cells

Purpose

Efficient intracellular delivery of a therapeutic compound is an important feature of smart drug delivery systems (SDDS). Modification of a carrier structure with a cell-penetrating ligand, ie, cholesterol moiety, is a strategy to improve cellular uptake. Cholesterol end-capped poly(N-isopropylacrylamide)s offer a promising foundation for the design of efficient thermoresponsive drug delivery systems.

Methods

A series of cholesterol end-capped poly(N-isopropylacrylamide)s (PNIPAAm) with number-average molar masses ranging from 3200 to 11000 g·mol^–1 were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization from original xanthate-functionalized cholesterol and self-assembled into micelles. The physicochemical characteristics and cytotoxicity of cholesterol end-capped poly(N-isopropylacrylamide)s have been thoroughly investigated.

Results

Phase transition temperature dependence on the molecular weight and hydrophilic/hydrophobic ratio in the polymers were observed in water. Biological test results showed that the obtained materials, both in disordered and micellar form, are non-hemolytic, highly compatible with fibroblasts, and toxic to glioblastoma cells. It was found that the polymer termini dictates the mode of action of the system.

Conclusion

The cholesteryl moiety acts as a cell-penetrating agent, which enables disruption of the plasma membrane and in effect leads to the restriction of the tumor growth. Cholesterol end-capped PNIPAAm showing in vitro anticancer efficacy can be developed not only as drug carriers but also as components of combined/synergistic therapy.

A facile and efficient approach for hypertrophic scar therapy via DNA-based transdermal drug delivery

The transdermal drug delivery approach has been considered a potential therapy for human hypertrophic scars (HSs) instead of current uncomfortable surgical excision, local injection and laser therapy. However, a facile and efficient drug delivery method is urgently needed to overcome the skin barrier of transdermal administration. Herein, we employed a DNA-Fe nanoparticle delivery system via Fe ion driven self-assembly to satisfy the requirement of transdermal administration for HS therapy. Doxorubicin hydrochloride (DOX) as one of the widely used anticancer drugs was employed to treat the hyperplasia of abnormal skin fibrous tissue. Both in vitro and in vivo experiments of the DOX loaded DNA-Fe nanoparticles (DOX@DNA-Fe NPs) were performed to demonstrate the penetration ability, rapid drug release, and scar-inhibiting effects. This facile and efficient approach for HS therapy via a DNA-based transdermal drug delivery system may provide more possibilities for the development of transdermal administration.

Dual-responsive doxorubicin-loaded nanomicelles for enhanced cancer therapy

BACKGROUND

The enhancement of tumor retention and cellular uptake of drugs are important factors in maximizing anticancer therapy and minimizing side effects of encapsulated drugs. Herein, a delivery nanoplatform, armed with a pH-triggered charge-reversal capability and self-amplifiable reactive oxygen species (ROS)-induced drug release, is constructed by encapsulating doxorubicin (DOX) in pH/ROS-responsive polymeric micelle.

RESULTS

The surface charge of this system was converted from negative to positive from pH 7.4 to pH 6.8, which facilitated the cellular uptake. In addition, methionine-based system was dissociated in a ROS-rich and acidic intracellular environment, resulting in the release of DOX and α-tocopheryl succinate (TOS). Then, the exposed TOS segments further induced the generation of ROS, leading to self-amplifiable disassembly of the micelles and drug release.

CONCLUSIONS

We confirms efficient DOX delivery into cancer cells, upregulation of tumoral ROS level and induction of the apoptotic capability in vitro. The system exhibits outstanding tumor inhibition capability in vivo, indicating that dual stimuli nano-system has great potential to function as an anticancer drug delivery platform.

Biomimetic Magnetite Nanoparticles as Targeted Drug Nanocarriers and Mediators of Hyperthermia in an Experimental Cancer Model

Simple Summary

The application of simultaneous and different strategies to treat cancer appears a promising therapeutic approach. Herein we proposed the application of chemotherapy combined with a magnetic nanocarrier delivery system to an in vitro and an in vivo experimental mammary carcinoma model. Drug-loaded biomimetic magnetic nanoparticle can be directed and concentrated on the tumor cells or site by the apposition of a magnet. Moreover, these nanoparticles can respond to an alternating magnetic field by developing hyperthermia around 43 °C, a temperature at which tumor cells, but not healthy cells, are particularly sensitive and thus induced to death. Indeed, when this nanoformulation is injected in vivo in the tumor site, and hyperthermia is generated, the combined chemo-thermal therapy mediated by these drug-loaded magnetic nanoparticles have a stronger therapeutic benefit compared to that carried out by the chemotherapeutic alone. These nanoformulation and strategy are thus promising tools for translational applications in cancer therapy.

Abstract

Biomimetic magnetic nanoparticles mediated by magnetosome proteins (BMNPs) are potential innovative tools for cancer therapy since, besides being multifunctional platforms, they can be manipulated by an external gradient magnetic field (GMF) and/or an alternating magnetic field (AMF), mediating targeting and hyperthermia, respectively. We evaluated the cytocompatibility/cytotoxicity of BMNPs and Doxorubicin (DOXO)-BMNPs in the presence/absence of GMF in 4T1 and MCF-7 cells as well as their cellular uptake. We analyzed the biocompatibility and in vivo distribution of BMNPs as well as the effect of DOXO-BMNPs in BALB/c mice bearing 4T1 induced mammary carcinomas after applying GMF and AMF. Results: GMF enhanced the cell uptake of both BMNPs and DOXO-BMNPs and the cytotoxicity of DOXO-BMNPs. BMNPs were biocompatible when injected intravenously in BALB/c mice. The application of GMF on 4T1 tumors after each of the repeated (6×) iv administrations of DOXO-BMNPs enhanced tumor growth inhibition when compared to any other treatment, including that with soluble DOXO. Moreover, injection of DOXO-BMNPs in the tumor combined with application of an AMF resulted in a significant tumor weight reduction. These promising results show the suitability of BMNPs as magnetic nanocarriers for local targeted chemotherapy and as local agents for hyperthermia.

Stimulus-Responsive Nanomedicines for Disease Diagnosis and Treatment

Stimulus-responsive drug delivery systems generally aim to release the active pharmaceutical ingredient (API) in response to specific conditions and have recently been explored for disease treatments. These approaches can also be extended to molecular imaging to report on disease diagnosis and management. The stimuli used for activation are based on differences between the environment of the diseased or targeted sites, and normal tissues. Endogenous stimuli include pH, redox reactions, enzymatic activity, temperature and others. Exogenous site-specific stimuli include the use of magnetic fields, light, ultrasound and others. These endogenous or exogenous stimuli lead to structural changes or cleavage of the cargo carrier, leading to release of the API. A wide variety of stimulus-responsive systems have been developed-responsive to both a single stimulus or multiple stimuli-and represent a theranostic tool for disease treatment. In this review, stimuli commonly used in the development of theranostic nanoplatforms are enumerated. An emphasis on chemical structure and property relationships is provided, aiming to focus on insights for the design of stimulus-responsive delivery systems. Several examples of theranostic applications of these stimulus-responsive nanomedicines are discussed.

Adenine-Functionalized Supramolecular Micelles for Selective Cancer Chemotherapy

Functional supramolecular micelles containing self-complementary multiple hydrogen bonding adenine groups (A-PPG) can spontaneously self-assemble into stable nanosized micelles in aqueous solution. These micelles can be used to selectively deliver anticancer drugs to cancer cells and effectively promote tumor cell death via apoptosis, without harming normal cells. The drug-loaded micelles exhibit tunable drug-loading capacity and rapid pH-triggered drug release under acidic conditions, as well as a high drug-entrapment stability in serum-rich media due to the reversible hydrogen-bonded adenine-adenine interactions within the micellar interior; these properties are critical to achieving effective chemotherapeutic drug delivery and controlled drug release. In vitro assays show that the drug-loaded micelles exert significant cytotoxic effects on cancer cells, with minimal effects on normal cells under physiological conditions. Cytotoxicity assays using A-PPG micelles loaded with different anticancer drugs confirm these effects. Importantly, cellular internalization and flow cytometric analyses demonstrate that the adenine moieties within A-PPG micelles significantly increase selective endocytic uptake of the supramolecular micelles by cancer cells, which in turn induce apoptotic cell death and substantially enhance the response to chemotherapy. Thus, A-PPG micelles can improve the safety and efficacy of cancer chemotherapy.

Smart stimuli-responsive biopolymeric nanomedicines for targeted therapy of solid tumors

Solid tumors form a permissive microenvironment with irregular features, including high pressured tumor interstitial fluid with acidic pH, co-adaptation of cancer cells with other cells like the immune system cells, abnormal metabolism and anomalous overexpression of various pieces of molecular machinery. The functional expressions of several oncomarkers in different solid tumors have led to the development of targeted drug-delivery systems (DDSs). As a new class of DDSs, stimuli-responsive nanomedicines (SRNMs) have been developed using advanced nanobiomaterials such as biopolymers that show excellent biocompatibility with low inherent immunogenicity. In this review, we aim to overview different types of SRNMs, present deep insights into the stimuli-responsive biopolymers and discuss the most up-to-date progress in the design and development of SRNMs used as advanced DDSs for targeted therapy of cancer.

Janus nanocarrier powered by bi-enzymatic cascade system for smart delivery

We report herein the assembly of an integrated nanodevice with bi-enzymatic cascade control for on-command cargo release. This nanocarrier is based on Au-mesoporous silica Janus nanoparticles capped at the mesoporous face with benzimidazole/β-cyclodextrin-glucose oxidase pH-sensitive gate-like ensembles and functionalized with invertase on the gold face. The rationale for this delivery mechanism is based on the invertase-mediated hydrolysis of sucrose yielding glucose, which is further transformed into gluconic acid by glucose oxidase causing the disruption of the pH-sensitive supramolecular gates at the Janus nanoparticles. This enzyme-powered device was successfully employed in the autonomous and on-demand delivery of doxorubicin in HeLa cancer cells.

Safety Considerations of Cancer Nanomedicine-A Key Step toward Translation

The rate of translational effort of nanomedicine requires strategic planning of nanosafety research in order to enable clinical trials and safe use of nanomedicine in patients. Herein, the experiences that have emerged based on the safety data of classic liposomal formulations in the space of oncology are discussed, along with a description of the new challenges that need to be addressed according to the rapid expansion of nanomedicine platform beyond liposomes. It is valuable to consider the combined use of predictive toxicological assessment supported by deliberate investigation on aspects such as absorption, distribution, metabolism, and excretion (ADME) and toxicokinetic profiles, the risk that may be introduced during nanomanufacture, unique nanomaterials properties, and nonobvious nanosafety endpoints, for example. These efforts will allow the generation of investigational new drug-enabling safety data that can be incorporated into a rational infrastructure for regulatory decision-making. Since the safety assessment relates to nanomaterials, the investigation should cover the important physicochemical properties of the material that may lead to hazards when the nanomedicine product is utilized in humans.

Prevention of Obesity Related Diseases through Laminarin-induced targeted delivery of Bindarit

Rationale: The developement of oral targeted therapeutics for obesity and obesity-related diseases is challenging, as these diseases involve multiple lesions distributed throughout the whole body. Herein, we report a successful stragety for targeted oral delivery of bindarit to multiple obesity-related lesions including inflamed adipose tissue, fatty liver and atherosclerotic plaques.

Methods: The computer simulation from atomstic to mesoscale was first applied for designing bindarit-loaded nanoparticles (pBIN) and laminarin-modified bindarit-loaded nanoparticles (LApBIN). Then pBIN were suceesfully prepared using a dialysis procedure, and LApBIN were prepared though the interaction bewtween laminarin and pBIN. The physiochemical properties, in vitro and in vivo pharmacokinetics, oral targeting capability and in vivo efficacy of LApBIN in various obesity-related diseases were examined.

Results: LApBIN were sucessfully designed and prepared. Following oral administration of LApBIN, the nanoparticles could be sucessully orally adsorbed and translocated to monocytes. Contributed by the recruitment of monocytes to multiple obesity-related lesions, LApBIN successfully delivered bindarit to these lesions, and effectively suppressed inflammation there, which exerted successful preventive effects on high-fat-diet-induced obesity, insulin resistance, fatty liver and atherosclerosis.

Conclusions:This strategy could represent a promising approach to develop effective oral treatments for obesity and other metabolic diseases.

Doxorubicin-loaded composite nanogels for cancer treatment

Nanogels as a versatile vehicle for doxorubicin have attracted great attention during the last decade. Since a nanogel composite device transport encapsulated drugs to the site of action and release them in a desirable time-frame, it could provide higher therapeutic effect. By implementation of different polymers, polymer/inorganic NPs and various crosslinking chemistry, it is possible to fabricate novel composite nanogel systems with favorable characteristics such as smart intelligent systems or multipurpose platforms. Due to high stability, good drug loading capacity for hydrophobic and hydrophilic agents, nanogels introduce great opportunity in pharmaceutical innovations. Composite nanogels show capability in gene, drug and diagnostic agents' delivery while providing an ideal platform for theranostic purposes as multifunctional systems. Doxorubicin as an anticancer agent is widely used against numerous cancers. Due to high systemic toxicity of doxorubicin, there is still need for its safe and specific delivery to the site of action. In this regard, so many efforts have been put in by the researchers for preparation of different nanogel formulations of doxorubicin in order to produce more efficient formulations. This review focuses on design, fabrication, advantages and disadvantages of composite nanogel-based doxorubicin formulations.

Sensitization of drug resistant sarcoma tumors by membrane modulation via short chain sphingolipid-containing nanoparticles

Nanoparticles such as liposomes are able to overcome cancer treatment challenges such as multidrug resistance by increasing the bioavailability of the encapsulated drug, bypassing drug pumps or through targeting resistant cells. Here, we merge enhanced drug delivery by nanotechnology with tumor cell membrane modulation combined in a single formulation. This is achieved through the incorporation of Short chain sphingolipids (SCSs) in the liposomal composition, which permeabilizes cell membranes to amphiphilic drugs such as Doxorubicin (Dxr). To study the mechanism and capability of SCS-containing nanodevices to overcome Dxr resistance, a sensitive uterine sarcoma cell line, MES-SA, and a resistant derived cell line, MES-SA/MX2, were used. The mechanism of resistance was explored by lipidomics and flow cytometry, revealing significant differences in lipid composition and in P glycoprotein (Pgp) expression. In vitro assays show that SCS liposomes were able to reverse cell resistance, and importantly, display a higher net effect on resistant than sensitive cells. SCS lipids modulated the cell membrane of MES-SA/MX2 drug resistant cells, while Pgp expression was not affected. Furthermore, SCS-modified liposomes were evaluated in a sarcoma xenograft model on drug accumulation, pharmacokinetics and efficacy. SCS liposomes improved Dxr levels in tumor nuclei of MES-SA/MX2 tumor cells, which was accompanied by a delay in tumor growth of the resistant model. Here we show that Dxr accumulation in tumor cells by SCS-modified liposomes was especially improved in Dxr resistant cells, rendering Dxr as effective as in sensitive cells. Moreover, this phenomenon translated to improved efficacy when Dxr liposomes where modified with SCSs in the drug resistant tumor model, while no benefit was seen in the sensitive tumors.

Biocompatibility of Biomaterials for Nanoencapsulation: Current Approaches

Nanoencapsulation is an approach to circumvent shortcomings such as reduced bioavailability, undesirable side effects, frequent dosing and unpleasant organoleptic properties of conventional drug delivery systems. The process of nanoencapsulation involves the use of biomaterials such as surfactants and/or polymers, often in combination with charge inducers and/or ligands for targeting. The biomaterials selected for nanoencapsulation processes must be as biocompatible as possible. The type(s) of biomaterials used for different nanoencapsulation approaches are highlighted and their use and applicability with regard to haemo- and, histocompatibility, cytotoxicity, genotoxicity and carcinogenesis are discussed.

Controlled anti-cancer drug release through advanced nano-drug delivery systems: Static and dynamic targeting strategies

Advances in nanomedicine, including early cancer detection, targeted drug delivery, and personalized approaches to cancer treatment are on the rise. For example, targeted drug delivery systems can improve intracellular delivery because of their multifunctionality. Novel endogenous-based and exogenous-based stimulus-responsive drug delivery systems have been proposed to prevent the cancer progression with proper drug delivery. To control effective dose loading and sustained release, targeted permeability and individual variability can now be described in more-complex ways, such as by combining internal and external stimuli. Despite these advances in release control, certain challenges remain and are identified in this research, which emphasizes the control of drug release and applications of nanoparticle-based drug delivery systems. Using a multiscale and multidisciplinary approach, this study investigates and analyzes drug delivery and release strategies in the nanoparticle-based treatment of cancer, both mathematically and clinically.

Monodisperse Hollow MnO2 with Biodegradability for Efficient Targeted Drug Delivery

The development of new nanocarriers with desired degradability and targeted ability is of great significance for efficient drug delivery. In this work, a monodisperse hollow structured MnO₂ (H-MnO₂) with a mesoporous shell is prepared and functionalized for efficient targeted drug delivery. The highly monodisperse H-MnO₂ with a uniform morphology was obtained by in situ growing MnO₂ on solid silica nanoparticles and subsequently removing the silica core. Then, the H-MnO₂ is successively modified with polyethylene glycol and targeted molecule folate (FA). The resultant H-MnO₂-FA shows excellent colloidal stability and high drug-loading content (∼58.2%) of the antitumor drug doxorubicin hydrochloride (DOX). The H-MnO₂-FA possesses acid-responsive T₁-weighted magnetic resonance imaging ability. The pH-dependent biodegradation behavior of H-MnO₂-FA is directly observed in vitro and confirmed by in vivo imaging, which is expected to favor the potential clearance of this hollow structured nanocarrier and eliminate its long-term toxicity. In addition, the DOX-loaded H-MnO₂-FA also demonstrates excellent cancer cell-killing effect and tumor inhibition efficacy.

NHF-derived carbon dots: prevalidation approach in breast cancer treatment

Metastatic breast cancer dominates the female cancer-related mortality. Tumour-associated molecules represents a crucial for early disease detection and identification of novel therapeutic targets. Nanomaterial technologies provide promising novel approaches to disease diagnostics and therapeutics. In the present study we extend the investigations of antitumoral properties of Carbon Dots prepared from N-hydroxyphthalimide (CD-NHF) precursor. We evaluate the effect of CD-NHF on tumour cell migration and invasion in vitro and their impact on tumour progression using an in vivo model. Furthermore, we investigate the molecular mechanisms involved in CD-NHF antitumour effects. In vivo mammary tumours were induced in Balb/c female mice by injecting 4T1 cells into the mammary fat pad. Conditional treatment with CD-NHF significantly impair both migration and invasion of metastatic breast cancer cells. The presence of CD-NHF within the 3D cell cultures strongly inhibited the malignant phenotype of MDA-MB-231, 4T1 and MCF-7 cells in 3D culture, resulting in culture colonies lacking invasive projections and reduction of mammospheres formation. Importantly, breast tumour growth and metastasis dissemination was significantly reduced upon CD-NHF treatments in a syngeneic mouse model and is associated with down-regulation of Ki67 and HSP90 expression. CD-NHF nanostructures provide exciting perspective for improving treatment outcome in breast cancer.

Tumor Microenvironment-Responsive Peptide-Based Supramolecular Drug Delivery System

Physical and biochemical differences between tumor tissues and normal tissues provide promising triggering factors that can be utilized to engineer stimuli-responsive drug delivery platforms for cancer treatment. Rationally designed peptide-based supramolecular architectures can perform structural conversion by responding to the tumor microenvironment and achieve the controlled release of antitumor drugs. This mini review summarizes recent approaches for designing internal trigger-responsive drug delivery platforms using peptide-based materials. Peptide assemblies that exhibit a stimuli-responsive structural conversion upon acidic pH, high temperature, high oxidative potential, and the overexpressed proteins in tumor tissues are emphatically introduced. We also discuss the challenges of current peptide-based supramolecular delivery platforms against cancer.

Nucleic acid-based drug delivery strategies

Nucleic acids have not been widely considered as an optimal material for drug delivery. Indeed, unmodified nucleic acids are enzymatically unstable, too hydrophilic for cell uptake and payload encapsulation, and may cause unintended biological responses such as immune system activation and prolongation of the blood coagulation pathway. Recently, however, three major areas of development surrounding nucleic acids have made it worthwhile to reconsider their role for drug delivery. These areas include DNA/RNA nanotechnology, multivalent nucleic acid nanostructures, and nucleic acid aptamers, which, respectively, provide the ability to engineer nanostructures with unparalleled levels of structural control, completely reverse certain biological properties of linear/cyclic nucleic acids, and enable antibody-level targeting using an all-nucleic acid construct. These advances, together with nucleic acids' ability to respond to various stimuli (engineered or natural), have led to a rapidly increasing number of drug delivery systems with potential for spatiotemporally controlled drug release. In this review, we discuss recent progress in nucleic acid-based drug delivery strategies, their potential, unique use cases, and risks that must be overcome or avoided.

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.

Tumor microenvironment responsive drug delivery systems

Conventional tumor-targeted drug delivery systems (DDSs) face challenges, such as unsatisfied systemic circulation, low targeting efficiency, poor tumoral penetration, and uncontrolled drug release. Recently, tumor cellular molecules-triggered DDSs have aroused great interests in addressing such dilemmas. With the introduction of several additional functionalities, the properties of these smart DDSs including size, surface charge and ligand exposure can response to different tumor microenvironments for a more efficient tumor targeting, and eventually achieve desired drug release for an optimized therapeutic efficiency. This review highlights the recent research progresses on smart tumor environment responsive drug delivery systems for targeted drug delivery. Dynamic targeting strategies and functional moieties sensitive to a variety of tumor cellular stimuli, including pH, glutathione, adenosine-triphosphate, reactive oxygen species, enzyme and inflammatory factors are summarized. Special emphasis of this review is placed on their responsive mechanisms, drug loading models, drawbacks and merits. Several typical multi-stimuli responsive DDSs are listed. And the main challenges and potential future development are discussed.

An Overview of Coumarin as a Versatile and Readily Accessible Scaffold with Broad-Ranging Biological Activities

Privileged structures have been widely used as an effective template for the research and discovery of high value chemicals. Coumarin is a simple scaffold widespread in Nature and it can be found in a considerable number of plants as well as in some fungi and bacteria. In the last years, these natural compounds have been gaining an increasing attention from the scientific community for their wide range of biological activities, mainly due to their ability to interact with diverse enzymes and receptors in living organisms. In addition, coumarin nucleus has proved to be easily synthetized and decorated, giving the possibility of designing new coumarin-based compounds and investigating their potential in the treatment of various diseases. The versatility of coumarin scaffold finds applications not only in medicinal chemistry but also in the agrochemical field as well as in the cosmetic and fragrances industry. This review is intended to be a critical overview on coumarins, comprehensive of natural sources, metabolites, biological evaluations and synthetic approaches.

Advances in drug delivery systems: Work in progress still needed?

A new era of science and technology has emerged in pharmaceutical research with focus on developing novel drug delivery systems for oral administration. Conventional dosage forms like tablets and capsules are associated with a low bioavailability, frequent application, side effects and hence patient noncompliance. By developing novel strategies for drug delivery, researchers embraced an alternative to traditional drug delivery systems. Out of those, fast dissolving drug delivery systems are very eminent among pediatrics and geriatrics. Orally disintegrating films are superior over fast dissolving tablets as the latter are assigned with the risk of suffocation. Due to their ability of bypassing the dissolution and the first pass effect after oral administration, self-emulsifying formulations have also become increasingly popular in improving oral bioavailability of hydrophobic drugs. Osmotic devices enable a controlled drug delivery independent upon gastrointestinal conditions using osmosis as driving force. The advances in nanotechnology and the variety of possible materials and formulation factors enable a targeted delivery and triggered release. Vesicular systems can be easily modified as required and provide a controlled and sustained drug delivery to a specific site.

This work provides an insight of the novel approaches in drug delivery covering the critical comparison between traditional and novel “advanced-designed” systems.

Yolk-shell nanovesicles endow glutathione-responsive concurrent drug release and T1 MRI activation for cancer theranostics

The effort of incorporating therapeutic drugs with imaging agents has been one of the mainstreams of nanomedicine, which holds great promise in cancer treatment in terms of monitoring therapeutic drug activity and evaluating prognostic index. However, it is still technically challenging to develop nanomedicine endowing a spatiotemporally controllable mechanism of drug release and activatable imaging capability. Here, we developed a yolk-shell type of GSH-responsive nanovesicles (NVs) in which therapeutic drug (Doxorubicin, DOX) and magnetic resonance imaging (MRI) contrast agent (ultrasmall paramagnetic iron oxide nanoparticles, USPIO NPs) formed complexes (denoted as USD) and were encapsulated inside the NVs. The formation of USD complexes is mediated by both the electrostatic adsorption between DOX and poly(acrylic acid) (PAA) polymers and the DOX-iron coordination effect on USPIO NPs. The obtained USD NVs showed a unique yolk-shell structure with restrained drug activity and quenched T1 MRI contrast ability which, on the other hand, can respond to glutathione (GSH) and lead to drug release and T1 contrast activation in a spatiotemporally concurrent manner. Furthermore, the USD NVs exhibited great potential to kill HCT116 cancer cells in vitro and effectively inhibit the tumor growth in vivo. This study may shed light on the design of sophisticated nanotheranostics in precision nanomedicine.

Near IR responsive targeted integrated lipid polymer nanoconstruct for enhanced magnolol cytotoxicity in breast cancer

Advances in cancer nanotechnology aim at improving specificity and effectiveness for tumor treatment. Amalgamation of different treatment modalities is expected to provide better cancer combating. Herein, We developed a long circulating nanocarrier comprising trastuzumab (TZB) surface modified polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) co-encapsulating magnolol (Mag) and gold nanoparticles (GNPs). A modified single step nanoprecipitation method was adopted ensuring particle coating with D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) while co-encapsulating GNPs. TZB was then anchored on NPs surface using a carbodiimide chemistry. The cytotoxicity of the developed system was evaluated with and without photothermal irradiation. NPs cellular uptake was then followed using confocal microscopical imaging. A hybrid matrix composed of PLGA/TPGS and surface decorated with TZB with a conjugation efficiency of ˃65%, was confirmed via FTIR, ¹HNMR. GNPs could only be included in the NPs, when placed in the organic phase as evidenced by the shifted GNPs surface plasmonic resonance and confirmed via imaging coupled with energy dispersive X-ray analysis. Optimized NPs (136.1 ± 1.3 nm, −8.2 ± 1 mV and Mag encapsulation efficiency of 81.4 ± 1.8%) were able to boost Mag cytotoxicity on breast cancer cells while providing a selective multifunctional therapy with an added photothermal effect.

Crossing the Blood-Brain Barrier: A Review on Drug Delivery Strategies for Treatment of the Central Nervous System Diseases

Many drugs have been designed to treat diseases of the central nervous system (CNS), especially neurodegenerative diseases. However, the presence of tight junctions at the blood-brain barrier has often compromised the efficiency of drug delivery to target sites in the brain. The principles of drug delivery systems across the blood-brain barrier are dependent on substrate-specific (i.e. protein transport and transcytosis) and non-specific (i.e. transcellular and paracellular) transport pathways, which are crucial factors in attempts to design efficient drug delivery strategies. This review describes how the blood-brain barrier presents the main challenge in delivering drugs to treat brain diseases and discusses the advantages and disadvantages of ongoing neurotherapeutic delivery strategies in overcoming this limitation. In addition, we discuss the application of colloidal carrier systems, particularly nanoparticles, as potential tools for therapy for the CNS diseases.

Controlled Release of Therapeutics from Thermoresponsive Nanogels: A Thermal Magnetic Resonance Feasibility Study

Thermal magnetic resonance (ThermalMR) accommodates radio frequency (RF)-induced temperature modulation, thermometry, anatomic and functional imaging, and (nano)molecular probing in an integrated RF applicator. This study examines the feasibility of ThermalMR for the controlled release of a model therapeutics from thermoresponsive nanogels using a 7.0-tesla whole-body MR scanner en route to local drug-delivery-based anticancer treatments. The capacity of ThermalMR is demonstrated in a model system involving the release of fluorescein-labeled bovine serum albumin (BSA-FITC, a model therapeutic) from nanometer-scale polymeric networks. These networks contain thermoresponsive polymers that bestow environmental responsiveness to physiologically relevant changes in temperature. The release profile obtained for the reference data derived from a water bath setup used for temperature stimulation is in accordance with the release kinetics deduced from the ThermalMR setup. In conclusion, ThermalMR adds a thermal intervention dimension to an MRI device and provides an ideal testbed for the study of the temperature-induced release of drugs, magnetic resonance (MR) probes, and other agents from thermoresponsive carriers. Integrating diagnostic imaging, temperature intervention, and temperature response control, ThermalMR is conceptually appealing for the study of the role of temperature in biology and disease and for the pursuit of personalized therapeutic drug delivery approaches for better patient care.

New formulations based on salicyl-imine-chitosan hydrogels for prolonged drug release

The objective of this paper was to investigate the new formulations based on salicyl-imine-chitosan hydrogels as potential controlled drug release systems. They were prepared by in situ hydrogelation of chitosan with salicylaldehyde in the presence of diclofenac sodium salt (DCF) as model drug. FTIR, X-ray Spectroscopy, POM and SEM techniques were used to confirm the structural, supramolecular and morphological particularities of the formulations. Swelling test, in vitro enzymatic biodegradation and release profile were investigated in similar conditions mimicking the in vivo environment, and the release mechanism was assessed by fitting into five mathematical models. It was established that the formulations have the capacity to release DCF in a sustained manner for 10 days rate, the drug release rate being correlated to the crosslinking density and hydrogelation speed. The biodegradation occurred in three main stages, reaching a mass loss of 48% after 21 days. In order to be used in the biomedical field, the in vivo biocompatibility of the formulations was investigated on experimental rats. After 7 days of subcutaneous implantation, no influence on the hematologic profile, liver, kidney or immune defence capacity were observed, suggesting these formulations as valuable materials for biomedical devices.

Smart Nanotheranostics Responsive to Pathological Stimuli

The development of nanotheranostics represents one of the most dynamic technological frontiers in the treatment of different pathological conditions. With the goal in mind to generate nanocarriers with both therapeutic and diagnostic properties, current research aims at implementing these technologies with multiple functions, including targeting, multimodal imaging, and synergistic therapies. The working mechanism of some nanotheranostics relies on physical, chemical, and biological triggers allowing for the activation of the therapeutic and/or the diagnostic properties only at the diseased site. In this review, we explored new advances in the development of smart nanotheranostics responsive to pathological stimuli, including altered pH, oxidative stress, enzymatic expression, and reactive biological molecules with a deep focus on the material used in the field to generate the particles in the context of the analyzed disease.

Morphology tunable and acid-sensitive dextran-doxorubicin conjugate assemblies for targeted cancer therapy

Stimuli-responsive and targetable nanomedicine systems have been widely applied as effective modalities for drug delivery and tumor therapeutics. Particle shape is also important for the biodistribution and cellular uptake in drug delivery applications. Here, morphology tunable and acid-responsive dextran-doxorubicin conjugate assemblies of DD-M and DDF-V for targeted doxorubicin (DOX) delivery were constructed, which contain the following favorable advantages: (1) one-pot synthesis of the drug loaded system with a Schiff base reaction is a green chemistry method which is better than the conventional drug conjugation/encapsulation methods. (2) The morphology of the nanoparticles could be regulated from a micelle (DD-M) to vesicle (DDF-V) structure by either introducing folic acid (FA) or not. (3) The abundant hydroxyl groups and electronegativity give DD-M and DDF-V superior stability in the physiological environment. (4) Besides, the multifunctional DDF-V with its important merits including tumor-targeting ability and acid-responsiveness is specific for DOX delivery in cancer therapy. (5) Compared to free DOX and DD-M, DDF-V displayed enhanced anti-tumor efficacy both in vitro and in vivo without obvious systematic toxicity. The morphology tunable, acid-sensitive and targetable nanosystem could be a promising strategy for site-specific drug delivery and potential cancer therapy in the future.

Recent advances in celluloses and their hybrids for stimuli-responsive drug delivery

The limitations of existing drug delivery systems (DDS) such as non-specific bio-distribution and poor selectivity have led to the exploration of a variety of carrier platforms to facilitate highly desirable and efficient drug delivery. Stimuli-responsive DDS are one of the most versatile and innovative approach to steer the compounds to the intended sites by exploiting their responsiveness to a range of various triggers. Preparation of stimuli-responsive DDS using celluloses and their derivatives offer a remarkable advantage over conventional polymer materials. In this review, we highlight on state-of-art progress in developing cellulose/cellulose hybrid stimuli-responsive DDS, which covers the preparation techniques, physicochemical properties, basic principles and, mechanisms of stimuli effect on drug release from various types of cellulose based carriers, through recent innovative investigations. Attention has been paid to endogenous stimuli (pH, temperature, redox gradient and ionic-strength) responsive DDS and exogenous stimuli (light, magnetic field and electric field) responsive DDS, where the cellulose-based materials have been extensively employed. Furthermore, the current challenges and future prospects of these DDS are also discussed at the end.

Synthesis, Characterization, and In Vitro Studies of an Reactive Oxygen Species (ROS)-Responsive Methoxy Polyethylene Glycol-Thioketal-Melphalan Prodrug for Glioblastoma Treatment

Glioblastoma (GBM) is the most frequent and aggressive primary tumor of the brain and averages a life expectancy in diagnosed patients of only 15 months. Hence, more effective therapies against this malignancy are urgently needed. Several diseases, including cancer, are featured by high levels of reactive oxygen species (ROS), which are possible GBM hallmarks to target or benefit from. Therefore, the covalent linkage of drugs to ROS-responsive molecules can be exploited aiming for a selective drug release within relevant pathological environments. In this work, we designed a new ROS-responsive prodrug by using Melphalan (MPH) covalently coupled with methoxy polyethylene glycol (mPEG) through a ROS-cleavable group thioketal (TK), demonstrating the capacity to self-assembly into nanosized micelles. Full chemical-physical characterization was conducted on the polymeric-prodrug and proper controls, along with in vitro cytotoxicity assayed on different GBM cell lines and “healthy” astrocyte cells confirming the absence of any cytotoxicity of the prodrug on healthy cells (i.e. astrocytes). These results were compared with the non-ROS responsive counterpart, underlining the anti-tumoral activity of ROS-responsive compared to the non-ROS-responsive prodrug on GBM cells expressing high levels of ROS. On the other hand, the combination treatment with this ROS-responsive prodrug and X-ray irradiation on human GBM cells resulted in an increase of the antitumoral effect, and this might be connected to radiotherapy. Hence, these results represent a starting point for a rationale design of innovative and tailored ROS-responsive prodrugs to be used in GBM therapy and in combination with radiotherapy.

Multifunctional carriers for controlled drug delivery

In the review we describe a method for concentration of anionic liposomes with encapsulated water-soluble substances within a small volume via electrostatic liposome adsorption on the surface of polymer particles with grafted cationic chains (spherical polycationic brushes), or cationic microgel particles. Dozens of intact liposomes can be bound to each polymer particle, the resulting polymer/liposome complex does not dissociate into the original components in a physiological solution. This allows fabrication of multi-liposomal complexes (MLCs) with a required ratio of encapsulated substances. Two approaches are discussed for the synthesis of stimuli-sensitive MLCs. The first is to incorporate the conformation switch, morpholinocyclohexanol-based lipid, into the liposomal membrane thus forming pH-sensitive liposomes capable of releasing their cargo when acidifying the surrounding solution. These liposomes complexed with the brushes release encapsulated substances much faster than the uncomplexed liposomes. The second is to adsorb liposomes on cationic thermo-responsive microgels. The resulting MLCs contracts upon heating over a volume phase transition temperature from the swollen to the collapsed state of microgel, thus causing the adsorbed liposomes to change drastically their morphology and release an encapsulated substance. Complexation of anionic liposomes with chitosan microgels and polylactide micelles gives MLCs which degrade in the presence of enzymes down to small particles, 10–15 nm in diameter. A novel promising approach suggests that immobilized liposomes can act as a capacious depot for biologically active compounds and ensure their controllable leakage to surrounding solution.

Potential Use of Extracellular Vesicles Generated by Microbubble-Assisted Ultrasound as Drug Nanocarriers for Cancer Treatment

Extracellular vesicles (EVs)-carrying biomolecules derived from parental cells have achieved substantial scientific interest for their potential use as drug nanocarriers. Ultrasound (US) in combination with microbubbles (MB) have been shown to trigger the release of EVs from cancer cells. In the current study, the use of microbubbles-assisted ultrasound (USMB) to generate EVs containing drug cargo was investigated. The model drug, CellTracker™ green fluorescent dye (CTG) or bovine serum albumin conjugated with fluorescein isothiocyanate (BSA FITC) was loaded into primary human endothelial cells in vitro using USMB. We found that USMB loaded CTG and BSA FITC into human endothelial cells (HUVECs) and triggered the release of EVs containing these compounds in the cell supernatant within 2 h after treatment. The amount of EV released seemed to be correlated with the increase of US acoustic pressure. Co-culturing these EVs resulted in uptake by the recipient tumour cells within 4 h. In conclusion, USMB was able to load the model drugs into endothelial cells and simultaneously trigger the release of EVs-carrying model drugs, highlighting the potential of EVs as drug nanocarriers for future drug delivery in cancer.

Insights on Ultrafiltration-Based Separation for the Purification and Quantification of Methotrexate in Nanocarriers

The evaluation of encapsulation efficiency is a regulatory requirement for the characterization of drug delivery systems. However, the difficulties in efficiently separating nanomedicines from the free drug may compromise the achievement of accurate determinations. Herein, ultrafiltration was exploited as a separative strategy towards the evaluation of methotrexate (MTX) encapsulation efficiency in nanostructured lipid carriers and polymeric nanoparticles. The effect of experimental conditions such as pH and the amount of surfactant present in the ultrafiltration media was addressed aiming at the selection of suitable conditions for the effective purification of nanocarriers. MTX-loaded nanoparticles were then submitted to ultrafiltration and the portions remaining in the upper compartment of the filtering device and in the ultrafiltrate were collected and analyzed by HPLC-UV using a reversed-phase (C18) monolithic column. A short centrifugation time (5 min) was suitable for establishing the amount of encapsulated MTX in nanostructured lipid carriers, based on the assumption that the free MTX concentration was the same in the upper compartment and in the ultrafiltrate. The defined conditions allowed the efficient separation of nanocarriers from the free drug, with recoveries of >85% even when nanoparticles were present in cell culture media and in pig skin surrogate from permeation assays.

MoS2@C nanosphere as near infrared / pH dual response platform for chemical photothermal combination treatment

The three-dimensional urchin-like MoS2@C nanocomposite was successfully synthesized via one-step hydrothermal synthesis approach. The as-prepared MoS2@C nanoparticles exhibits strong absorb, high photothermal conversion ability (40.8 %), superb biocompatibility and high drug loading capacity for doxorubicin (52.34 %). In vitro drug release experiments show a pH, temperature and near infrared laser-triggered doxorubicinhydro release profile that enhances therapeutic anticancer effects. The drug release curve increased step by step under laser irradiation, and the accumulative delivery amount reached to 64.59 %, which was about 2 times of that without laser irradiation. By using DOX-loaded nano-platform, effective synergistic photothermal therapy for cancer can be achieved and has been systematically verified in vitro. Cell viability experiments showed that the survival rate of cells with MoS2 @C-DOX was only 25.8 %. Therefore, this work presents carbon-based nanoparticles with significant characteristics and is used as a highly potential therapeutic nano-platform for cancer treatment.