Nanoscale Drug Delivery and Hyperthermia: The Materials Design and Preclinical and Clinical Testing of Low Temperature-Sensitive Liposomes Used in Combination with Mild Hyperthermia in the Treatment of Local Cancer

Augmentation of the EPR effect by mild hyperthermia to improve nanoparticle delivery to the tumor

The clinical translation of the nanoparticle (NP)-based anticancer therapies is still unsatisfactory due to the heterogeneity of the enhanced permeability and retention (EPR) effect. Despite the promising preclinical outcome of the pharmacological EPR enhancers, their systemic toxicity can limit their clinical application. Hyperthermia (HT) presents an efficient tool to augment the EPR by improving tumor blood flow (TBF) and vascular permeability, lowering interstitial fluid pressure (IFP), and disrupting the structure of the extracellular matrix (ECM). Furthermore, the HT-triggered intravascular release approach can overcome the EPR effect. In contrast to pharmacological approaches, HT is safe and can be focused to cancer tissues. Moreover, HT conveys direct anti-cancer effects, which improve the efficacy of the anti-cancer agents encapsulated in NPs. However, the clinical application of HT is challenging due to the heterogeneous distribution of temperature within the tumor, the length of the treatment and the complexity of monitoring.

Mild hyperthermia with magnetic resonance- guided high intensity focused ultrasound combined with salvage chemoradiation for recurrent rectal cancer

INTRODUCTION

Pelvic recurrences from rectal cancer present a challenging clinical scenario. Hyperthermia represents an innovative treatment option in combination with concurrent chemoradiation to enhance therapeutic effect. We provide the initial results of a prospective single center feasibility study (NCT02528175) for patients undergoing rectal cancer retreatment using concurrent chemoradiation and mild hyperthermia with MR-guided high intensity focused ultrasound (MR-HIFU).

METHODS

All patients were deemed ineligible for salvage surgery and were evaluated in a multidisciplinary fashion with a surgical oncologist, radiation oncologist and medical oncologist. Radiation was delivered to a dose of 30.6 Gy in 1.8 Gy per fraction with concurrent capecitabine. MR-HIFU was delivered on days 1, 8 and 15 of concurrent chemoradiation. Our primary objective was feasibility and toxicity.

RESULTS

Six patients (total 11 screened) were treated with concurrent chemoradiation and mild hyperthermia with MR-HIFU. Tumor size varied between 3.1-16.6 cm. Patients spent an average of 228 min in the MRI suite and sonication with the external transducer lasted an average of 35 min. There were no complications on the day of the MR-HIFU procedure and all acute toxicities (no grade >/=3 toxicities) resolved after completion of treatment. There were no late grade >/=3 toxicities.

CONCLUSION

Mild hyperthermia with MR-HIFU, in combination with concurrent chemoradiation for appropriately selected patients, is safe for localized pelvic recurrences from rectal cancer. The potential for MR-HIFU to be applied in the recurrent setting in rectal cancer treatment requires further technical development and prospective evaluation.

Magnetic Modulation of Biochemical Synthesis in Synthetic Cells

Synthetic cells can be constructed from diverse molecular components, without the design constraints associated with modifying 'living' biological systems. This can be exploited to generate cells with abiotic components, creating functionalities absent in biology. One example is magnetic responsiveness, the activation and modulation of encapsulated biochemical processes using a magnetic field, which is absent from existing synthetic cell designs. This is a critical oversight, as magnetic fields are uniquely bio-orthogonal, noninvasive, and highly penetrative. Here, we address this by producing artificial magneto-responsive organelles by coupling thermoresponsive membranes with hyperthermic Fe3O4 nanoparticles and embedding them in synthetic cells. Combining these systems enables synthetic cell microreactors to be built using a nested vesicle architecture, which can respond to alternating magnetic fields through in situ enzymatic catalysis. We also demonstrate the modulation of biochemical reactions by using different magnetic field strengths and the potential to tune the system using different lipid compositions. This platform could unlock a wide range of applications for synthetic cells as programmable micromachines in biomedicine and biotechnology.

Development and approval of novel injectables: enhancing therapeutic innovations

INTRODUCTION

Novel injectables possess applications in both local and systemic therapeutics delivery. The advancement in utilized materials for the construction of complex injectables has tremendously upgraded their safety and efficacy.

AREAS COVERED

This review focuses on various strategies to produce novel injectables, including oily dispersions, in situ forming implants, injectable suspensions, microspheres, liposomes, and antibody-drug conjugates. We herein present a detailed description of complex injectable technologies and their related drug formulations permitted for clinical use by the United States Food and Drug Administration (USFDA). The excipients used, their purpose and the challenges faced during manufacturing such formulations have been critically discussed.

EXPERT OPINION

Novel injectables can deliver therapeutic agents in a controlled way at the desired site. However, several challenges persist with respect to their genericization. Astronomical costs incurred by innovator companies during product development, complexity of the product itself, supply limitations with respect to raw materials, intricate manufacturing processes, patent evergreening, product life-cycle extensions, relatively few and protracted generic approvals contribute to the exorbitant prices and access crunch. Moreover, regulatory guidance are grossly underdeveloped and significant efforts have to be directed toward development of effective characterization techniques.

The presence of uncoated gold nanoparticle aggregates may alter the phase of phosphatidylcholine lipid as evidenced by vibrational spectroscopies

Spherical structures built from uni- and multilamellar lipid bilayers (LUV and MLV) are nowadays considered not just as nanocarriers of various kinds of therapeutics, but also as the vehicles that, when coupled with gold (Au) nanoparticles (NPs), can also serve as a tool for imaging and discriminating healthy and diseased tissues. Since the presence of Au NPs or their aggregates may affect the properties of the drug delivery vehicle, we investigated how the shape and position of Au NP aggregates adsorbed on the surface of MLV affect the arrangement and conformation of lipid molecules. By preparing MLVs constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of uncoated Au NP aggregates found i) both within liposome core and on the surface of the outer lipid bilayer, or ii) adsorbed on the outer lipid bilayer surface only, we demonstrated the maintenance of lipid bilayer integrity by microscopic techniques (cryo-TEM, and AFM). The employment of SERS and FTIR-ATR techniques enabled us not only to elucidate the lipid interaction pattern and their orientation in regards to Au NP aggregates but also unequivocally confirmed the impact of Au NP aggregates on the persistence/breaking of van der Waals interactions between hydrocarbon chains of DPPC.

Implantable smart hyperthermia nanofibers for cancer therapy: Challenges and opportunities

Nanofibers (NFs) with practical drug-loading capacities, high stability, and controllable release have caught the attention of investigators due to their potential applications in on-demand drug delivery devices. Developing novel and efficient multidisciplinary management of locoregional cancer treatment through the design of smart NF-based systems integrated with combined chemotherapy and hyperthermia could provide stronger therapeutic advantages. On the other hand, implanting directly at the tumor area is a remarkable benefit of hyperthermia NF-based drug delivery approaches. Hence, implantable smart hyperthermia NFs might be very hopeful for tumor treatment in the future and provide new avenues for developing highly efficient localized drug delivery systems. Indeed, features of the smart NFs lead to the construction of a reversibly flexible nanostructure that enables hyperthermia and facile switchable release of antitumor agents to eradicate cancer cells. Accordingly, this study covers recent updates on applications of implantable smart hyperthermia NFs regarding their current scope and future outlook. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

The Impact of Silver Nanoparticle-Induced Photothermal Therapy and Its Augmentation of Hyperthermia on Breast Cancer Cells Harboring Intracellular Bacteria

Breast cancer can harbor intracellular bacteria, which may have an impact on metastasis and therapeutic responses. Silver nanoparticles are FDA-approved for their antimicrobial potential, plus they have pleiotropic benefits for eradicating cancer cells. In the current work we synthesized photothermal silver nanoparticles (AgNPs) with an absorption at 800 nm for heat generation when exposed to near-infrared laser irradiation. Breast cell lines MCF 10A, MCF7, and MDA MB 231 were infected with Pseudomonas aeruginosa, and their response to AgNPs, heat, or photothermal therapy (PTT) was evaluated. The results demonstrate that the application of a brief heating of cells treated with AgNPs offers a synergistic benefit in killing both infected and non-infected cells. Using 10 µg/mL of AgNPs plus laser stimulation induced a temperature change of 12 °C, which was sufficient for reducing non-infected breast cells by 81-94%. Infected breast cells were resistant to PTT, with only a reduction of 45-68%. In the absence of laser stimulation, 10 µg/mL of AgNPs reduced breast cell populations by 10-65% with 24 h of exposure. This concentration had no impact on the survival of planktonic bacteria with or without laser stimulation, although infected breast cells had a 42-90% reduction in intracellular bacteria. Overall, this work highlights the advantages of AgNPs for the generation of heat, and to augment the benefits of heat, in breast cancer cells harboring intracellular infection.

Heat-Triggered Release of Dexamethasone from Thermosensitive Liposomes Using Prodrugs or Excipients

Dexamethasone (DXM) is a potent glucocorticoid with an anti-inflammatory and anti-angiogenic activity which is widely clinically used. Systemic side effects limit the long-term use of DXM in patients requiring formulations which deliver and selectively release the drug to the diseased tissues. This in vitro study compares the suitability of DXM and commonly used prodrugs dexamethasone-21-phosphate (DXMP) and dexamethasone-21-palmitate (DP) as well as DXM complexed by 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD) for the use in thermosensitive liposomes (TSL). DXM showed a poor retention and a low final drug:lipid ratio in a 1,2-dipalmitoyl-sn‑glycero-3-phosphodiglycerol-based TSL (DPPG2-TSL) and a low-temperature sensitive liposome (LTSL). In contrast to DXM, DXMP and DP were stably retained at 37 °C in TSL in serum and could be encapsulated with high drug:lipid ratios in DPPG2-TSL and LTSL. DXMP showed a rapid release at mild hyperthermia (HT) from both TSL in serum, whereas DP remained incorporated in the TSL bilayer. According to release experiments with carboxyfluorescein (CF), HP-γ-CD and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) are suitable vehicles for the loading of DXM into DPPG2-TSL and LTSL. Complexation of DXM with HP-γ-CD increased the aqueous solubility of the drug leading to approx. ten times higher DXM:lipid ratio in DPPG2-TSL and LTSL in comparison to un-complexed DXM. Both DXM and HP-γ-CD showed increased release at HT in comparison to 37 °C in serum. In conclusion, DXMP and DXM complexed by HP-γ-CD represent promising candidates for TSL delivery.

Immunomodulation and targeted drug delivery with high intensity focused ultrasound (HIFU): Principles and mechanisms

High intensity focused ultrasound (HIFU) is a non-invasive and non-ionizing sonic energy-based therapeutic technology for inducing thermal and non-thermal effects in tissues. Depending on the parameters, HIFU can ablate tissues by heating them to >55 °C to induce denaturation and coagulative necrosis, improve radio- and chemo-sensitizations and local drug delivery from nanoparticles at moderate hyperthermia (~41-43 °C), and mechanically fragment cells using acoustic cavitation (also known as histotripsy). HIFU has already emerged as an attractive modality for treating human prostate cancer, veterinary cancers, and neuromodulation. Herein, we comprehensively review the role of HIFU in enhancing drug delivery and immunotherapy in soft and calcified tissues. Specifically, the ability of HIFU to improve adjuvant treatments from various classes of drugs is described. These crucial insights highlight the opportunities and challenges of HIFU technology and its potential to support new clinical trials and translation to patients.

Recent Preclinical and Clinical Progress in Liposomal Doxorubicin

Doxorubicin (DOX) is a potent anti-cancer agent that has garnered great interest in research due to its high efficacy despite dose-limiting toxicities. Several strategies have been exploited to enhance the efficacy and safety profile of DOX. Liposomes are the most established approach. Despite the improvement in safety properties of liposomal encapsulated DOX (in Doxil and Myocet), the efficacy is not superior to conventional DOX. Functionalized (targeted) liposomes present a more effective system to deliver DOX to the tumor. Moreover, encapsulation of DOX in pH-sensitive liposomes (PSLs) or thermo-sensitive liposomes (TSLs) combined with local heating has improved DOX accumulation in the tumor. Lyso-thermosensitive liposomal DOX (LTLD), MM-302, and C225-immunoliposomal(IL)-DOX have reached clinical trials. Further functionalized PEGylated liposomal DOX (PLD), TSLs, and PSLs have been developed and evaluated in preclinical models. Most of these formulations improved the anti-tumor activity compared to the currently available liposomal DOX. However, the fast clearance, the optimization of ligand density, stability, and release rate need more investigations. Therefore, we reviewed the latest approaches applied to deliver DOX more efficiently to the tumor, preserving the benefits obtained from FDA-approved liposomes.

Ultrasound-mediated nano drug delivery for treating cancer: Fundamental physics to future directions

The application of biocompatible nanocarriers in medicine has provided several benefits over conventional treatment methods. However, achieving high treatment efficacy and deep penetration of nanocarriers in tumor tissue is still challenging. To address this, stimuli-responsive nano-sized drug delivery systems (DDSs) are an active area of investigation in delivering anticancer drugs. While ultrasound is mainly used for diagnostic purposes, it can also be applied to affect cellular function and the delivery/release of anticancer drugs. Therapeutic ultrasound (TUS) has shown potential as both a stand-alone anticancer treatment and a method to induce targeted drug release from nanocarrier systems. TUS approaches have been used to overcome various physiological obstacles, including endothelial barriers, the tumor microenvironment (TME), and immunological hurdles. Combining nanomedicine and ultrasound as a smart DDS can increase in situ drug delivery and improve access to impermeable tissues. Furthermore, smart DDSs can perform targeted drug release in response to distinctive TMEs, external triggers, or dual/multi-stimulus. This results in enhanced treatment efficacy and reduced damage to surrounding healthy tissue or organs at risk. Integrating DDSs and ultrasound is still in its early stages. More research and clinical trials are required to fully understand ultrasound's underlying physical mechanisms and interactions with various types of nanocarriers and different types of cells and tissues. In the present review, ultrasound-mediated nano-sized DDS, specifically focused on cancer treatment, is presented and discussed. Ultrasound interaction with nanoparticles (NPs), drug release mechanisms, and various types of ultrasound-sensitive NPs are examined. Additionally, in vitro, in vivo, and clinical applications of TUS are reviewed in light of the critical challenges that need to be considered to advance TUS toward an efficient, secure, straightforward, and accessible cancer treatment. This study also presents effective TUS parameters and safety considerations for this treatment modality and gives recommendations about system design and operation. Finally, future perspectives are considered, and different TUS approaches are examined and discussed in detail. This review investigates drug release and delivery through ultrasound-mediated nano-sized cancer treatment, both pre-clinically and clinically.

Use of stimulatory responsive soft nanoparticles for intracellular drug delivery

Drug delivery has made tremendous advances in the last decade. Targeted therapies are increasingly common, with intracellular delivery highly impactful and sought after. Intracellular drug delivery systems have limitations due to imprecise and non-targeted release profiles. One way this can be addressed is through using stimuli-responsive soft nanoparticles, which contain materials with an organic backbone such as lipids and polymers. The choice of biomaterial is essential for soft nanoparticles to be responsive to internal or external stimuli. The nanoparticle must retain its integrity and payload in non-targeted physiological conditions while responding to particular intracellular environments where payload release is desired. Multiple internal and external factors could stimulate the intracellular release of drugs from nanoparticles. Internal stimuli include pH, oxidation, and enzymes, while external stimuli include ultrasound, light, electricity, and magnetic fields. Stimulatory responsive soft nanoparticulate systems specifically utilized to modulate intracellular delivery of drugs are explored in this review.

Molecular Aspects and Therapeutic Implications of Herbal Compounds Targeting Different Types of Cancer

Due to genetic changes in DNA (deoxyribonucleic acid) sequences, cancer continues to be the second most prevalent cause of death. The traditional target-directed approach, which is confronted with the importance of target function in healthy cells, is one of the most significant challenges in anticancer research. Another problem with cancer cells is that they experience various mutations, changes in gene duplication, and chromosomal abnormalities, all of which have a direct influence on the potency of anticancer drugs at different developmental stages. All of these factors combine to make cancer medication development difficult, with low clinical licensure success rates when compared to other therapy categories. The current review focuses on the pathophysiology and molecular aspects of common cancer types. Currently, the available chemotherapeutic drugs, also known as combination chemotherapy, are associated with numerous adverse effects, resulting in the search for herbal-based alternatives that attenuate resistance due to cancer therapy and exert chemo-protective actions. To provide new insights, this review updated the list of key compounds that may enhance the efficacy of cancer treatment.

Stimuli-responsive vesicles as distributed artificial organelles for bacterial activation

Intercellular communication is a hallmark of living systems. As such, engineering artificial cells that possess this behavior has been at the heart of activities in bottom-up synthetic biology. Communication between artificial and living cells has potential to confer novel capabilities to living organisms that could be exploited in biomedicine and biotechnology. However, most current approaches rely on the exchange of chemical signals that cannot be externally controlled. Here, we report two types of remote-controlled vesicle-based artificial organelles that translate physical inputs into chemical messages that lead to bacterial activation. Upon light or temperature stimulation, artificial cell membranes are activated, releasing signaling molecules that induce protein expression in Escherichia coli. This distributed approach differs from established methods for engineering stimuli-responsive bacteria. Here, artificial cells (as opposed to bacterial cells themselves) are the design unit. Having stimuli-responsive elements compartmentalized in artificial cells has potential applications in therapeutics, tissue engineering, and bioremediation. It will underpin the design of hybrid living/nonliving systems where temporal control over population interactions can be exerted.

Magneto-Fluorescent Mesoporous Nanocarriers for the Dual-Delivery of Ofloxacin and Doxorubicin to Tackle Opportunistic Bacterial Infections in Colorectal Cancer

Cancer-related opportunistic bacterial infections are one major barrier for successful clinical therapies, often correlated to the production of genotoxic factors and higher cancer incidence. Although dual anticancer and antimicrobial therapies are a growing therapeutic fashion, they still fall short when it comes to specific delivery and local action in in vivo systems. Nanoparticles are seen as potential therapeutic vectors, be it by means of their intrinsic antibacterial properties and effective delivery capacity, or by means of their repeatedly reported modulation and maneuverability. Herein we report on the production of a biocompatible, antimicrobial magneto-fluorescent nanosystem (NANO3) for the delivery of a dual doxorubicin-ofloxacin formulation against cancer-related bacterial infections. The drug delivery capacity, rendered by its mesoporous silica matrix, is confirmed by the high loading capacity and stimuli-driven release of both drugs, with preference for tumor-like acidic media. The pH-dependent emission of its surface fluorescent SiQDs, provides an insight into NANO3 surface behavior and pore availability, with the SiQDs working as pore gates. Hyperthermia induces heat generation to febrile temperatures, doubling drug release. NANO3-loaded systems demonstrate significant antimicrobial activity, specifically after the application of hyperthermia conditions. NANO3 structure and antimicrobial properties confirm their potential use in a future dual anticancer and antimicrobial therapeutical vector, due to their drug loading capacity and their surface availability for further modification with bioactive, targeting species.

Cardiolipin for Enhanced Cellular Uptake and Cytotoxicity of Thermosensitive Liposome-Encapsulated Daunorubicin toward Breast Cancer Cell Lines

Daunorubicin (DNR) and cardiolipin (CL) were co-delivered using thermosensitive liposomes (TSLs). 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1-myristoyl-2-stearoyl-sn-glycero-3-phosphocholine (MSPC), cholesterol, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] or DSPE-mPEG (2000) and CL were used in the formulation of liposomes at a molar ratio of 57:40:30:3:20, respectively. CL forms raft-like microdomains that may relocate and change lipid organization of the outer and inner mitochondrial membranes. Such transbilayer lipid movement eventually leads to membrane permeabilization. TSLs were prepared by thin-film hydration (drug:lipid ratio 1:5) where DNR was encapsulated within the aqueous core of the liposomes and CL acted as a component of the lipid bilayer. The liposomes exhibited high drug encapsulation efficiency (>90%), small size (~115 nm), narrow size distribution (polydispersity index ~0.12), and a rapid release profile under the influence of mild hyperthermia. The liposomes also exhibited ~4-fold higher cytotoxicity against MDA-MB-231 cells compared to DNR or liposomes similar to DaunoXome® (p < 0.001). This study provides a basis for developing a co-delivery system of DNR and CL encapsulated in liposomes for treatment of breast cancer.

Temperature-sensitive polymers to promote heat-triggered drug release from liposomes: Towards bypassing EPR

Heat-triggered drug release from temperature-sensitive nanocarriers upon the application of mild hyperthermia is a promising approach to achieve site-specific delivery of drugs. The combination of mild hyperthermia (41-42 °C) and temperature-sensitive liposomes (TSL) that undergo lipid phase-transition and drug release has been studied extensively and has shown promising therapeutic outcome in a variety of animal tumor models as well as initial indications of success in humans. Sensitization of liposomes to mild hyperthermia by means of exploiting the thermal behavior of temperature-sensitive polymers (TSP) provides novel opportunities. Recently, TSP-modified liposomes (TSPL) have shown potential for enhancing tumor-directed drug delivery, either by triggered drug release or by triggered cell interactions in response to heat. In this review, we describe different classes of TSPL, and analyze and discuss the mechanisms and kinetics of content release from TSPL in response to local heating. In addition, the impact of lipid composition, polymer and copolymer characteristics, serum components and PEGylation on the mechanism of content release and TSPL performance is addressed. This is done from the perspective of rationally designing TSPL, with the overall goal of conceiving efficient strategies to increase the efficacy of TSPL plus hyperthermia to improve the outcome of targeted anticancer therapy.

Physically stimulus-responsive nanoparticles for therapy and diagnosis

Nanoparticles offer numerous advantages in various fields of science, particularly in medicine. Over recent years, the use of nanoparticles in disease diagnosis and treatments has increased dramatically by the development of stimuli-responsive nano-systems, which can respond to internal or external stimuli. In the last 10 years, many preclinical studies were performed on physically triggered nano-systems to develop and optimize stable, precise, and selective therapeutic or diagnostic agents. In this regard, the systems must meet the requirements of efficacy, toxicity, pharmacokinetics, and safety before clinical investigation. Several undesired aspects need to be addressed to successfully translate these physical stimuli-responsive nano-systems, as biomaterials, into clinical practice. These have to be commonly taken into account when developing physically triggered systems; thus, also applicable for nano-systems based on nanomaterials. This review focuses on physically triggered nano-systems (PTNSs), with diagnostic or therapeutic and theranostic applications. Several types of physically triggered nano-systems based on polymeric micelles and hydrogels, mesoporous silica, and magnets are reviewed and discussed in various aspects.

A mechanoresponsive nano-sized carrier achieves intracellular release of drug on external ultrasound stimulus

Control over intracellular release of therapeutic compounds incorporated into nano-carriers will open new possibilities for targeted treatments of various diseases including cancer, and viral and bacterial infections. Here we report our study on mechanoresponsive nano-sized liposomes which, following internalization by cells, achieve intracellular delivery of encapsulated cargo on application of external ultrasound stimulus. This is demonstrated in a bespoke cell reporter system designed to assess free drug in cytoplasm. Biophysical analyses show that drug release is attributable to the action of a mechanoresponsive spiropyran-based compound embedded in the liposomal lipid membrane. Exposure to external ultrasound stimulus results in opening of the molecular structure of the embedded spiropyran, a consequent increase in liposomal lipid membrane fluidity, and size-dependent release of encapsulated model drugs, all pointing to lipid bilayer perturbation. The study hence illustrates feasibility of the proposed concept where intracellular drug release from mechanoresponsive liposomes can be triggered on demand by external ultrasound stimulus.

The study illustrates feasibility of the proposed concept where intracellular drug release from mechanoresponsive liposomes can be triggered on demand by external ultrasound stimulus.

Recent advances in remotely controlled pulsatile drug delivery systems

Pharmaceutical technology is drastically developing to enhance the efficacy and safety of drug therapy. Pulsatile delivery systems, in turn, gained attraction for their ability to deliver the right drug amount to the right body site, at the right time which is advantageous over conventional dosage forms. Their use is associated with increased patient compliance and allows on-demand drug delivery as well as customizable therapy. Recent technologies have been implemented to further develop pulsatile delivery systems for more precise determination of the dosage timing and duration as well as the location of drug release. Great interests are directed towards externally regulated pulsatile release systems which will be the focus of this review. The recent advances will be highlighted in remotely controlled delivery systems. This includes electro responsive, light-responsive, ultrasound responsive, and magnetically induced pulsatile systems as well as wirelessly controlled implantable systems. The current status of these technologies will be discussed as well as the recent investigations and future applications.

Ultrasound and nanomaterial: an efficient pair to fight cancer

Ultrasounds are often used in cancer treatment protocols, e.g. to collect tumor tissues in the right location using ultrasound-guided biopsy, to image the region of the tumor using more affordable and easier to use apparatus than MRI and CT, or to ablate tumor tissues using HIFU. The efficacy of these methods can be further improved by combining them with various nano-systems, thus enabling: (i) a better resolution of ultrasound imaging, allowing for example the visualization of angiogenic blood vessels, (ii) the specific tumor targeting of anti-tumor chemotherapeutic drugs or gases attached to or encapsulated in nano-systems and released in a controlled manner in the tumor under ultrasound application, (iii) tumor treatment at tumor site using more moderate heating temperatures than with HIFU. Furthermore, some nano-systems display adjustable sizes, i.e. nanobubbles can grow into micro-bubbles. Such dual size is advantageous since it enables gathering within the same unit the targeting properties of nano bubbles via EPR effect and the enhanced ultrasound contrasting properties of micro bubbles. Interestingly, the way in which nano-systems act against a tumor could in principle also be adjusted by accurately selecting the nano-system among a large choice and by tuning the values of the ultrasound parameters, which can lead, due to their mechanical nature, to specific effects such as cavitation that are usually not observed with purely electromagnetic waves and can potentially help destroying the tumor. This review highlights the clinical potential of these combined treatments that can improve the benefit/risk ratio of current cancer treatments.

Insights into Nanomedicine for Head and Neck Cancer Diagnosis and Treatment

Head and neck cancers rank sixth among the most common cancers today, and the survival rate has remained virtually unchanged over the past 25 years, due to late diagnosis and ineffective treatments. They have two main risk factors, tobacco and alcohol, and human papillomavirus infection is a secondary risk factor. These cancers affect areas of the body that are fundamental for the five senses. Therefore, it is necessary to treat them effectively and non-invasively as early as possible, in order to do not compromise vital functions, which is not always possible with conventional treatments (chemotherapy or radiotherapy). In this sense, nanomedicine plays a key role in the treatment and diagnosis of head and neck cancers. Nanomedicine involves using nanocarriers to deliver drugs to sites of action and reducing the necessary doses and possible side effects. The main purpose of this review is to give an overview of the applications of nanocarrier systems to the diagnosis and treatment of head and neck cancer. Herein, several types of delivery strategies, radiation enhancement, inside-out hyperthermia, and theragnostic approaches are addressed.

Thermosensitive Polymers and Thermo-Responsive Liposomal Drug Delivery Systems

Temperature excursions within a biological milieu can be effectively used to induce drug release from thermosensitive drug-encapsulating nanoparticles. Oncological hyperthermia is of particular interest, as it is proven to synergistically act to arrest tumor growth when combined with optimally-designed smart drug delivery systems (DDSs). Thermoresponsive DDSs aid in making the drugs more bioavailable, enhance the therapeutic index and pharmacokinetic trends, and provide the spatial placement and temporal delivery of the drug into localized anatomical sites. This paper reviews the fundamentals of thermosensitive polymers, with a particular focus on thermoresponsive liposomal-based drug delivery systems.

Engineered strategies to enhance tumor penetration of drug-loaded nanoparticles

Nanocarriers have been widely employed in preclinical studies and clinical trials for the delivery of anticancer drugs. The most important causes of failure in clinical translation of nanocarriers is their inefficient accumulation and penetration which arises from special characteristics of tumor microenvironment such as insufficient blood supply, dense extracellular matrix, and elevated interstitial fluid pressure. Various strategies such as engineering extracellular matrix, optimizing the physicochemical properties of nanocarriers have been proposed to increase the depth of tumor penetration; however, these strategies have not been very successful so far. Novel strategies such as transformable nanocarriers, transcellular transport of peptide-modified nanocarriers, and bio-inspired carriers have recently been emerged as an advanced generation of drug carriers. In this study, the latest developments of nanocarrier-based drug delivery to solid tumor are presented with their possible limitations. Then, the prospects of advanced drug delivery systems are discussed in detail.

Magnetic nanoparticles and clusters for magnetic hyperthermia: optimizing their heat performance and developing combinatorial therapies to tackle cancer

Magnetic hyperthermia (MHT) is a therapeutic modality for the treatment of solid tumors that has now accumulated more than 30 years of experience. In the ongoing MHT clinical trials for the treatment of brain and prostate tumors, iron oxide nanoparticles are employed as intra-tumoral MHT agents under a patient-safe 100 kHz alternating magnetic field (AMF) applicator. Although iron oxide nanoparticles are currently approved by FDA for imaging purposes and for the treatment of anemia, magnetic nanoparticles (MNPs) designed for the efficient treatment of MHT must respond to specific physical-chemical properties in terms of magneto-energy conversion, heat dose production, surface chemistry and aggregation state. Accordingly, in the past few decades, these requirements have boosted the development of a new generation of MNPs specifically aimed for MHT. In this review, we present an overview on MNPs and their assemblies produced via different synthetic routes, focusing on which MNP features have allowed unprecedented heating efficiency levels to be achieved in MHT and highlighting nanoplatforms that prevent magnetic heat loss in the intracellular environment. Moreover, we review the advances on MNP-based nanoplatforms that embrace the concept of multimodal therapy, which aims to combine MHT with chemotherapy, radiotherapy, immunotherapy, photodynamic or phototherapy. Next, for a better control of the therapeutic temperature at the tumor, we focus on the studies that have optimized MNPs to maintain gold-standard MHT performance and are also tackling MNP imaging with the aim to quantitatively assess the amount of nanoparticles accumulated at the tumor site and regulate the MHT field conditions. To conclude, future perspectives with guidance on how to advance MHT therapy will be provided.

Preclinical Studies in Small Animals for Advanced Drug Delivery Using Hyperthermia and Intravital Microscopy

This paper presents three devices suitable for the preclinical application of hyperthermia via the simultaneous high-resolution imaging of intratumoral events. (Pre)clinical studies have confirmed that the tumor micro-environment is sensitive to the application of local mild hyperthermia. Therefore, heating is a promising adjuvant to aid the efficacy of radiotherapy or chemotherapy. More so, the application of mild hyperthermia is a useful stimulus for triggered drug release from heat-sensitive nanocarriers. The response of thermosensitive nanoparticles to hyperthermia and ensuing intratumoral kinetics are considerably complex in both space and time. To obtain better insight into intratumoral processes, longitudinal imaging (preferable in high spatial and temporal resolution) is highly informative. Our devices are based on (i) an external electric heating adaptor for the dorsal skinfold model, (ii) targeted radiofrequency application, and (iii) a microwave antenna for heating of internal tumors. These models, while of some technical complexity, significantly add to the understanding of effects of mild hyperthermia warranting implementation in research on hyperthermia.

Photosensitive drug delivery systems for cancer therapy: Mechanisms and applications

Over the past three decades, various photosensitive nanoparticles have been developed as potential therapies in human health, ranging from photodynamic therapy technologies that have already reached clinical use, to drug delivery systems that are still in the preclinical stages. Many of these systems are designed to achieve a high spatial and temporal on-demand drug release via phototriggerable mechanisms. This review examines the current clinical and experimental applications in cancer treatment of photosensitive drug release systems, including nanocarriers such as liposomes, micelles, polymeric nanoparticles, and hydrogels. We will focus on the three main physicochemical mechanisms of imparting photosensitivity to a delivery system: i) photochemical reactions (oxidation, cleavage, and polymerization), ii) photoisomerization, iii) and photothermal reactions. Photosensitive nanoparticles have a multitude of different applications including controlled drug release, resulting from physical/conformational changes in the delivery systems in response to light of specific wavelengths. Most of the recent research in these delivery systems has primarily focused on improving the efficacy and safety of cancer treatments such as photodynamic and photothermal therapy. Combinations of multiple treatment modalities using photosensitive nanoparticulate delivery systems have also garnered great interest in combating multi-drug resistant cancers due to their synergistic effects. Finally, the challenges and future potential of photosensitive drug delivery systems in biomedical applications is outlined.

EDTA-Gradient Loading of Doxorubicin into Ferrocene-Containing Liposomes: Effect of Lipid Composition and Visualization of Triggered Release by Cryo-TEM

Efficient delivery of therapeutic compounds to their sites of action has been a ubiquitous concern throughout the history of human medicine. The tumor microenvironment offers a variety of endogenous stimuli that may be exploited by a responsive nanocarrier, including heterogeneities in redox potential. In the early stages of the design of such responsive delivery systems, it is necessary to develop a comprehensive understanding of the biophysical mechanism by which the stimulus response occurs, as well as how the response may change from the inclusion of cargo compounds. We describe the optimization of lipid compositions for liposomes containing synthetic ferrocene-appended lipids to achieve highly efficient loading of doxorubicin via an ethylenediaminetetraacetic acid (EDTA) gradient. Liposomes containing ferrocenylated phospholipid are shown to be unstable to the loading conditions, while those including a ferrocenylated alkylammonium amphiphile obtain a near-quantitative loading efficiency. Calorimetric studies demonstrate that this instability is the consequence of the relative degree of lipid hydrolysis that occurs under the acidic loading conditions. Drug-loaded liposomes of the optimized composition are studied by cryo-TEM; the presence of doxorubicin aggregates is observed inside vesicles, and doxorubicin release, as well as the changes in membrane structure resulting from oxidant treatment, is also observed by cryogenic transmission electron microscopy (cryo-TEM). These results further demonstrate the potential of ferrocene lipids in the design of redox-responsive nanocarriers and begin to explore their possible role as probes of membrane dynamics.

Liposome Photosensitizer Formulations for Effective Cancer Photodynamic Therapy

Photodynamic therapy (PDT) is a promising non-invasive strategy in the fight against that which circumvents the systemic toxic effects of chemotherapeutics. It relies on photosensitizers (PSs), which are photoactivated by light irradiation and interaction with molecular oxygen. This generates highly reactive oxygen species (such as ¹O₂, H₂O₂, O₂, ·OH), which kill cancer cells by necrosis or apoptosis. Despite the promising effects of PDT in cancer treatment, it still suffers from several shortcomings, such as poor biodistribution of hydrophobic PSs, low cellular uptake, and low efficacy in treating bulky or deep tumors. Hence, various nanoplatforms have been developed to increase PDT treatment effectiveness and minimize off-target adverse effects. Liposomes showed great potential in accommodating different PSs, chemotherapeutic drugs, and other therapeutically active molecules. Here, we review the state-of-the-art in encapsulating PSs alone or combined with other chemotherapeutic drugs into liposomes for effective tumor PDT.

Drug Delivery by Ultrasound-Responsive Nanocarriers for Cancer Treatment

Conventional cancer chemotherapies often exhibit insufficient therapeutic outcomes and dose-limiting toxicity. Therefore, there is a need for novel therapeutics and formulations with higher efficacy, improved safety, and more favorable toxicological profiles. This has promoted the development of nanomedicines, including systems for drug delivery, but also for imaging and diagnostics. Nanoparticles loaded with drugs can be designed to overcome several biological barriers to improving efficiency and reducing toxicity. In addition, stimuli-responsive nanocarriers are able to release their payload on demand at the tumor tissue site, preventing premature drug loss. This review focuses on ultrasound-triggered drug delivery by nanocarriers as a versatile, cost-efficient, non-invasive technique for improving tissue specificity and tissue penetration, and for achieving high drug concentrations at their intended site of action. It highlights aspects relevant for ultrasound-mediated drug delivery, including ultrasound parameters and resulting biological effects. Then, concepts in ultrasound-mediated drug delivery are introduced and a comprehensive overview of several types of nanoparticles used for this purpose is given. This includes an in-depth compilation of the literature on the various in vivo ultrasound-responsive drug delivery systems. Finally, toxicological and safety considerations regarding ultrasound-mediated drug delivery with nanocarriers are discussed.

The effect of injected dose on localized tumor accumulation and cardiac uptake of doxorubicin in a Vx2 rabbit tumor model using MR-HIFU mild hyperthermia and thermosensitive liposomes

PURPOSE

When doxorubicin (DOX) is administered via lyso-thermosensitive liposomes (LTLD), mild hyperthermia enhances localized delivery to heated vs. unheated tumors. The optimal LTLD dose and the impact of different doses on systemic drug distribution are unknown.

Materials and methods: In this study, we evaluated local and systemic DOX delivery with three LTLD doses (0.1, 0.5, and 2.5 mg/kg) in a Vx2 rabbit tumor model. Temporally and spatially accurate controlled hyperthermia was achieved using a clinical MR-HIFU system for the intended heating duration (40 min).

Results: DOX concentration in tissues delivered from LTLD combined with MR-HIFU mild hyperthermia are dose-dependent, including heated/unheated tumor, heart, and other healthy organs. Higher DOX accumulation and tumor-to-heart drug concentration ratio, defined as the ratio of DOX delivered into the tumor vs the heart, were observed in heated tumors compared to unheated tumors in all three tested doses. The DOX uptake efficiency for each mg/kg of LTLD injected IV of heated tumor was significantly higher than that of unheated tumor and heart within the tested dose range (0.1-2.5 mg/kg). The DOX uptake for the heart linearly scaled up as a function of dose while that for the heated tumor showed some evidence of saturation at the high dose of 2.5 mg/kg.

Conclusions: These results provide guidance on clinical protocol design of hyperthermia-triggered drug delivery.

Liposome technologies towards colorectal cancer therapeutics

Colorectal cancer (CRC) is the third most common cancer and the fourth most common deadly cancer worldwide. After treatment with curative intent recurrence rates vary with staging 0-13% in Stage 1, 11-61% in S2 and 28-73% in Stage 3. The toxicity to healthy tissues from chemotherapy and radiotherapy and drug resistance severely affect the quality of life and cancer specific outcomes of CRC patients. To overcome some of these limitations, many efforts have been made to develop nanomaterial-based drug delivery systems. Among these nanocarriers, liposomes represented one of the most successful candidates in delivering targeted oncological treatment, improving safety profile and therapeutic efficacy of encapsulated drugs. In this review we will discuss liposome design with a particular focus on the targeting feature and triggering functions. We will also summarise the recent advances in liposomal delivery system for CRC treatment in both the preclinical and clinical studies. We will finally provide our perspectives on the liposome technology development for the future clinical translation. STATEMENT OF SIGNIFICANCE: Conventional treatments for colorectal cancer (CRC) severely affect the therapeutic effects for advanced patients. With the development of nanomedicines, liposomal delivery system appears to be one of the most promising nanocarriers for CRC treatment. In last three years several reviews in this area have been published focusing on the preclinical research and drug delivery function, which is a fairly narrow focus in the field of liposome technology for CRC therapy. Our review presented the most recent advances of the liposome technology (both clinical and preclinical applications) for CRC with strong potential for further clinical translation. We believe it will attract lots of attention from various audiences, including researchers, clinicians and the industry.

Optimized Photoactivatable Lipid Nanoparticles Enable Red Light Triggered Drug Release

Encapsulation of small molecule drugs in long-circulating lipid nanoparticles (LNPs) can reduce toxic side effects and enhance accumulation at tumor sites. A fundamental problem, however, is the slow release of encapsulated drugs from these liposomal systems at the disease site resulting in limited therapeutic benefit. Methods to trigger release at specific sites are highly warranted. Here, it is demonstrated that incorporation of ultraviolet (UV-A) or red-light photoswitchable-phosphatidylcholine analogs (AzoPC and redAzoPC) in conventional LNPs generates photoactivatable LNPs (paLNPs) having comparable structural integrity, drug loading capacity, and size distribution to the parent DSPC-cholesterol liposomes. It is shown that 65-70% drug release (doxorubicin) can be induced from these systems by irradiation with pulsed light based on trans-to-cis azobenzene isomerization. In vitro it is confirmed that paLNPs are non-toxic in the dark but convey cytotoxicity upon irradiation in a human cancer cell line. In vivo studies in zebrafish embryos demonstrate prolonged blood circulation and extravasation of paLNPs comparable to clinically approved formulations, with enhanced drug release following irradiation with pulsed light. Conclusively, paLNPs closely mimic the properties of clinically approved LNPs with the added benefit of light-induced drug release making them promising candidates for clinical development.

Characterizing the Structure and Interactions of Model Lipid Membranes Using Electrophysiology

The cell membrane is a protective barrier whose configuration determines the exchange both between intracellular and extracellular regions and within the cell itself. Consequently, characterizing membrane properties and interactions is essential for advancements in topics such as limiting nanoparticle cytotoxicity. Characterization is often accomplished by recreating model membranes that approximate the structure of cellular membranes in a controlled environment, formed using self-assembly principles. The selected method for membrane creation influences the properties of the membrane assembly, including their response to electric fields used for characterizing transmembrane exchanges. When these self-assembled model membranes are combined with electrophysiology, it is possible to exploit their non-physiological mechanics to enable additional measurements of membrane interactions and phenomena. This review describes several common model membranes including liposomes, pore-spanning membranes, solid supported membranes, and emulsion-based membranes, emphasizing their varying structure due to the selected mode of production. Next, electrophysiology techniques that exploit these structures are discussed, including conductance measurements, electrowetting and electrocompression analysis, and electroimpedance spectroscopy. The focus of this review is linking each membrane assembly technique to the properties of the resulting membrane, discussing how these properties enable alternative electrophysiological approaches to measuring membrane characteristics and interactions.

Improving Release of Liposome-Encapsulated Drugs with Focused Ultrasound and Vaporizable Droplet-Liposome Nanoclusters

Active targeted delivery of small molecule drugs is becoming increasingly important in personalized therapies, especially in cancer, brain disorders, and a wide variety of other diseases. However, effective means of spatial targeting and delivering high drug payloads in vivo are still lacking. Focused ultrasound combined with superheated phase-shift nanodroplets, which vaporize into microbubbles using heat and sound, are rapidly becoming a popular strategy for targeted drug delivery. Focused ultrasound can target deep tissue with excellent spatial precision and without using ionizing energy, thus can activate nanodroplets in circulation. One of the main limitations of this technology has been poor drug loading in the droplet core or the shell material. To address this need, we have developed a strategy to combine low-boiling point decafluorabutane and octafluoropropane (DFB and OFP) nanodroplets with drug-loaded liposomes, creating phase-changeable droplet-liposome clusters (PDLCs). We demonstrate a facile method of assembling submicron PDLCs with high drug-loading capacity on the droplet surface. Furthermore, we demonstrate that chemical tethering of liposomes in PDLCs enables a rapid release of their encapsulated cargo upon acoustic activation (>60% using OFP-based PDLCs). Rapid uncaging of small molecule drugs would make them immediately bioavailable in target tissue or promote better penetration in local tissue following intravascular release. PDLCs developed in this study can be used to deliver a wide variety of liposome-encapsulated therapeutics or imaging agents for multi-modal imaging applications. We also outline a strategy to deliver a surrogate encapsulated drug, fluorescein, to tumors in vivo using focused ultrasound energy and PDLCs.

Intriguing Biomedical Applications of Synthetic and Natural Cell-Derived Vesicles: A Comparative Overview

The significant role of a vesicle is well recognized; however, only lately has the advancement in biomedical applications started to uncover their usefulness. Although the concept of vesicles originates from cell biology, it later transferred to chemistry and material science to develop nanoscale artificial vesicles for biomedical applications. Herein, we examine different synthetic and biological vesicles and their applications in the biomedical field in general. As our understanding of biological vesicles increases, more suitable biomimicking synthetic vesicles will be developed. The comparative discussion between synthetic and natural vesicles for biomedical applications is a relevant topic, and we envision this could enable the development of a proper approach to realize the next-generation treatment goals.

Triggered Drug Release From Liposomes: Exploiting the Outer and Inner Tumor Environment

Since more than 40 years liposomes have being extensively studied for their potential as carriers of anticancer drugs. The basic principle behind their use for cancer treatment consists on the idea that they can take advantage of the leaky vasculature and poor lymphatic drainage present at the tumor tissue, passively accumulating in this region. Aiming to further improve their efficacy, different strategies have been employed such as PEGlation, which enables longer circulation times, or the attachment of ligands to liposomal surface for active targeting of cancer cells. A great challenge for drug delivery to cancer treatment now, is the possibility to trigger release from nanosystems at the tumor site, providing efficacious levels of drug in the tumor. Different strategies have been proposed to exploit the outer and inner tumor environment for triggering drug release from liposomes and are the focus of this review.

Building Blocks to Design Liposomal Delivery Systems

The flexibility of liposomal carriers does not just simply rely on their capability to encapsulate various types of therapeutic substances, but also on the large array of components used for designing liposome-based nanoformulations. Each of their components plays a very specific role in the formulation and can be easily replaced whenever a different therapeutic effect is desired. It is tempting to describe this by an analogy to Lego blocks, since a whole set of structures, differing in their features, can be designed using a certain pool of blocks. In this review, we focus on different design strategies, where a broad variety of liposomal components facilitates the attainment of straightforward control over targeting and drug release, which leads to the design of the most promising systems for drug delivery. The key aspects of this block-based architecture became evident after its implementation in our recent works on liposomal carriers of antisense oligonucleotides and statins, which are described in the last chapter of this review.

Hyperthermia and Temperature-Sensitive Nanomaterials for Spatiotemporal Drug Delivery to Solid Tumors

Nanotechnology has great capability in formulation, reduction of side effects, and enhancing pharmacokinetics of chemotherapeutics by designing stable or long circulating nano-carriers. However, effective drug delivery at the cellular level by means of such carriers is still unsatisfactory. One promising approach is using spatiotemporal drug release by means of nanoparticles with the capacity for content release triggered by internal or external stimuli. Among different stimuli, interests for application of external heat, hyperthermia, is growing. Advanced technology, ease of application and most importantly high level of control over applied heat, and as a result triggered release, and the adjuvant effect of hyperthermia in enhancing therapeutic response of chemotherapeutics, i.e., thermochemotherapy, make hyperthermia a great stimulus for triggered drug release. Therefore, a variety of temperature sensitive nano-carriers, lipid or/and polymeric based, have been fabricated and studied. Importantly, in order to achieve an efficient therapeutic outcome, and taking the advantages of thermochemotherapy into consideration, release characteristics from nano-carriers should fit with applicable clinical thermal setting. Here we introduce and discuss the application of the three most studied temperature sensitive nanoparticles with emphasis on release behavior and its importance regarding applicability and therapeutic potentials.

Encapsulated doxorubicin crystals influence lysolipid temperature-sensitive liposomes release and therapeutic efficacy in vitro and in vivo

Doxorubicin (DOX)-loaded lysolipid temperature-sensitive liposomes (LTSLs) are a promising stimuli-responsive drug delivery system that rapidly releases DOX in response to mild hyperthermia (HT). This study investigates the influence of loaded DOX crystals on the thermosensitivity of LTSLs and their therapeutic efficacy in vitro and in vivo. The properties of DOX crystals were manipulated using different remote loading methods (namely (NH₄)₂SO₄, NH₄-EDTA and MnSO₄) and varying the lipid:DOX weight ratio during the loading step. Our results demonstrated that (NH₄)₂SO₄ or NH₄-EDTA remote loading methods had a comparable encapsulation efficiency (EE%) into LTSLs in contrast to the low DOX EE% obtained using the metal complexation method. Cryogenic transmission electron microscopy (cryo-TEM) revealed key differences in the nature of DOX crystals formed inside LTSLs based on the loading buffer or/and the lipid:DOX ratio used, resulting in different DOX release profiles in response to mild HT. The in vitro assessment of DOX release/uptake in CT26 and PC-3 cells revealed that the use of a high lipid:DOX ratio exhibited a fast and controlled release profile in combination with mild HT, which correlated well with their cytotoxicity studies. Similarly, in vivo DOX release, tumour growth inhibition and mice survival rates were influenced by the physicochemical properties of LTSLs payload. This study demonstrates, for the first time, that the characteristics of DOX crystals loaded into LTSLs, and their conformational rearrangement during HT, are important factors that impact the TSLs performance in vivo.

Indocyanine Green and Curcumin Co-Loaded Nano-Fireball-Like Albumin Nanoparticles Based on Near-Infrared-Induced Hyperthermia for Tumor Ablation

Background

Indocyanine green (ICG) has received considerable interest as a biocompatible organic photothermal agent, and curcumin (Cur) is considered an attractive natural chemopreventive and chemotherapeutic compound. However, the in vivo applicability of ICG and Cur is significantly restricted by their poor ability to target tumors and their extremely low solubility.

Materials and Methods

To address these problems, ICG/Cur-loaded albumin nanoparticles (ICG-BSA-Cur-NPs) based on the nab^TM (nanoparticle albumin-bound) technology were applied to neuroblastomas in vivo.

Results

The fabricated ICG-BSA-Cur-NPs were found to be spherical, ~150 nm in size and highly dispersible and stable in aqueous solution. Approximately 80% of the incorporated ICG and Cur were gradually released from the NPs over 48 h. All formulations of ICG-BSA-Cur-NPs (5~20 µg/mL) showed efficient hyperthermia profiles (up to 50–60°C within 5 min) in response to 808-nm NIR laser irradiation in vitro and in vivo. Notably, ICG-BSA-Cur-NPs illuminated with 808-nm laser irradiation (1.5 W/cm²) showed excellent cytotoxicity toward N2a cells in vitro and undisputable antitumor efficacy in N2a-xenografted mice in vivo, compared to other tested sample groups (tumor volumes for PBS, BSA-Cur-NPs, free ICG, and ICG-BSA-Cur-NPs groups were 1408.6 ± 551.9, 1190.6 ± 343.6, 888.6 ± 566.2, and 103.0 ± 111.3 mm³, respectively).

Conclusion

We demonstrate that these hyperthermal chemotherapeutic ICG-BSA-Cur-NPs have potential as a future brain tumor treatment.

Next-Generation Polymeric Nanomedicines for Oncology: Perspectives and Future Directions

Precision polymers as advanced nanomedicines represent an appealing approach for the treatment of otherwise untreatable malignancies. By taking advantage of unique nanomaterial properties and implementing judicious design strategies, polymeric nanomedicines are able to be produced that overcome many barriers to effective treatment. Current key research focus areas anticipated to produce the greatest impact in polymer applications in nanomedicine for oncology include new strategies to achieve "active" targeting, polymeric pro-drug activation, and combinatorial polymer drug delivery approaches in combination with enhanced understanding of complex bio-nano interactions. These approaches, both in isolation or combination, form the next generation of precision nanomedicines with significant anticipated future health outcomes. Of necessity, these approaches will combine an intimate understanding of biological interactions with advanced materials design. This perspectives piece aims to highlight emerging opportunities that promise to be game changers in the nanomedicine oncology field. Discussed herein are current and next generation polymeric nanomedicines with a focus towards structures that are, or could, undergo clinical translation as well as highlight key advances in the field.

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.