Magnetic Gel Composites for Hyperthermia Cancer Therapy

Stimuli-responsive Biomaterials for Tissue Engineering Applications

The use of ''smart materials,'' or ''stimulus responsive'' materials, has proven useful in a variety of fields, including tissue engineering and medication delivery. Many factors, including temperature, pH, redox state, light, and magnetic fields, are being studied for their potential to affect a material's properties, interactions, structure, and/or dimensions. New tissue engineering and drug delivery methods are made possible by the ability of living systems to respond to both external stimuli and their own internal signals) for example, materials composed of stimuliresponsive polymers that self assemble or undergo phase transitions or morphology transformation. The researcher examines the potential of smart materials as controlled drug release vehicles in tissue engineering, aiming to enable the localized regeneration of injured tissue by delivering precisely dosed drugs at precisely timed intervals.

Self-Assembling Peptide-Based Magnetogels for the Removal of Heavy Metals from Water

In this study, we present the synthesis of a novel peptide-based magnetogel obtained through the encapsulation of γ-Fe2O3-polyacrylic acid (PAA) nanoparticles (γ-Fe2O3NPs) into a hydrogel matrix, used for enhancing the ability of the hydrogel to remove Cr(III), Co(II), and Ni(II) pollutants from water. Fmoc-Phe (Fluorenylmethoxycarbonyl-Phenylalanine) and diphenylalanine (Phe2) were used as starting reagents for the hydrogelator (Fmoc-Phe3) synthesis via an enzymatic method. The PAA-coated magnetic nanoparticles were synthesized in a separate step, using the co-precipitation method, and encapsulated into the peptide-based hydrogel. The resulting organic/inorganic hybrid system (γ-Fe2O3NPs-peptide) was characterized with different techniques, including FT-IR, Raman, UV-Vis, DLS, ζ-potential, XPS, FESEM-EDS, swelling ability tests, and rheology. Regarding the application in heavy metals removal from aqueous solutions, the behavior of the obtained magnetogel was compared to its precursors and the effect of the magnetic field was assessed. Four different systems were studied for the separation of heavy metal ions from aqueous solutions, including (1) γ-Fe2O3NPs stabilized with PAA, (γ-Fe2O3NPs); (2) Fmoc-Phe3 hydrogel (HG); (3) γ-Fe2O3NPs embedded in peptide magnetogel (γ-Fe2O3NPs@HG); and (4) γ-Fe2O3NPs@HG in the presence of an external magnetic field. To quantify the removal efficiency of these four model systems, the UV-Vis technique was employed as a fast, cheap, and versatile method. The results demonstrate that both Fmoc-Phe3 hydrogel and γ-Fe2O3NPs peptide magnetogel can efficiently remove all the tested pollutants from water. Interestingly, due to the presence of magnetic γ-Fe2O3NPs inside the hydrogel, the removal efficiency can be enhanced by applying an external magnetic field. The proposed magnetogel represents a smart multifunctional nanosystem with improved absorption efficiency and synergic effect upon applying an external magnetic field. These results are promising for potential environmental applications of γ-Fe2O3NPs-peptide magnetogels to the removal of pollutants from aqueous media.

Synthesis and Characterization of Novel Magnetic Nano-Biocomposite Hydrogels Based on Starch-g-poly(acrylic acid) Reinforced by Cellulose Nanofibers for Cu2+ Ion Removal

One of the crucial challenges of the adsorption process is to recapture the adsorbent from the solution, especially for adsorbents in powder form. This study synthesized a novel magnetic nano-biocomposite hydrogel adsorbent to successfully remove Cu²⁺ ions, followed by convenient recovery and reusability of the adsorbent. The Cu²⁺ adsorption capacity of starch-g-poly(acrylic acid)/cellulose nanofibers (St-g-PAA/CNFs) composite hydrogel and magnetic composite hydrogel (M-St-g-PAA/CNFs) was investigated and compared in both bulk and powder forms. Results showed that Cu²⁺ removal kinetics and swelling rate were improved by grinding the bulk hydrogel into powder form. The kinetic data and adsorption isotherm were best correlated with the pseudo-second-order and Langmuir models, respectively. The maximum monolayer adsorption capacity values of M-St-g-PAA/CNFs hydrogels loaded with 2 and 8 wt % Fe₃O₄ nanoparticles in 600 mg/L Cu²⁺ solution were found to be 333.33 and 555.56 mg/g, respectively, compared to 322.58 mg/g for the St-g-PAA/CNFs hydrogel. Vibrating sample magnetometry (VSM) results demonstrate that the magnetic hydrogel that included 2 and 8 wt % magnetic nanoparticles exhibited paramagnetic behavior with the magnetization of 0.6-0.66 and 1-1.04 emu/g at the plateau, respectively, which showed a proper magnetic property and good magnetic attraction in the magnetic field for separating the adsorbent from the solution. Also, the synthesized compounds were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). Finally, the magnetic bioadsorbent was successfully regenerated and reused for four treatment cycles.

Electrospun Magnetic Nanofiber Mats for Magnetic Hyperthermia in Cancer Treatment Applications-Technology, Mechanism, and Materials

The number of cancer patients is rapidly increasing worldwide. Among the leading causes of human death, cancer can be regarded as one of the major threats to humans. Although many new cancer treatment procedures such as chemotherapy, radiotherapy, and surgical methods are nowadays being developed and used for testing purposes, results show limited efficiency and high toxicity, even if they have the potential to damage cancer cells in the process. In contrast, magnetic hyperthermia is a field that originated from the use of magnetic nanomaterials, which, due to their magnetic properties and other characteristics, are used in many clinical trials as one of the solutions for cancer treatment. Magnetic nanomaterials can increase the temperature of nanoparticles located in tumor tissue by applying an alternating magnetic field. A very simple, inexpensive, and environmentally friendly method is the fabrication of various types of functional nanostructures by adding magnetic additives to the spinning solution in the electrospinning process, which can overcome the limitations of this challenging treatment process. Here, we review recently developed electrospun magnetic nanofiber mats and magnetic nanomaterials that support magnetic hyperthermia therapy, targeted drug delivery, diagnostic and therapeutic tools, and techniques for cancer treatment.

Magnetic Gels in Skin Cancer Treatment: A Review of Potential Applications in Diagnostics, Drug Delivery and Hyperthermia

Skin cancer (SC) is affecting an increasing number of people worldwide. Its lesions affect mainly the most exposed regions of the skin. SC is classified into to main categories: non-melanoma (basal cell carcinoma of the epidermis and squamous cell carcinoma) and melanoma (the abnormal proliferation of melanocytes, which is rarer, more hazardous, and more deadly). Prevention and early diagnosis are important actions, and surgery is often considered. After the removal of cancerous lesions, the local administration of medicine can guarantee anticancer therapeutic action, rapid healing and the recovery of tissue, ensuring the absence of recurrence. Magnetic gels (MGs) have attracted increased attention regarding their pharmaceutical and biomedical applications. They are magnetic nanoparticles (e.g., iron oxide nanoparticles) dispersed in a polymeric matrix, which constitute adaptive systems under a magnetic field. MGs can combine magnetic susceptibility, high elasticity, and softness, and are thus useful platforms for diagnostics, drug delivery, and also for hyperthermia. This manuscript reviews MGs as a technological strategy for the treatment of SC. An overview of SC and the treatment, types, and methods of preparing MGs are discussed. Moreover, the applications of MGs in SC and their future perspectives are considered. The combination of polymeric gels and magnetic nanoparticles continues to be investigated, and new products must hit the market. Clinical trials and new products are expected, due to the important advantages of MGs.

Gold-Nanoparticle Hybrid Nanostructures for Multimodal Cancer Therapy

With the urgent need for bio-nanomaterials to improve the currently available cancer treatments, gold nanoparticle (GNP) hybrid nanostructures are rapidly rising as promising multimodal candidates for cancer therapy. Gold nanoparticles (GNPs) have been hybridized with several nanocarriers, including liposomes and polymers, to achieve chemotherapy, photothermal therapy, radiotherapy, and imaging using a single composite. The GNP nanohybrids used for targeted chemotherapy can be designed to respond to external stimuli such as heat or internal stimuli such as intratumoral pH. Despite their promise for multimodal cancer therapy, there are currently no reviews summarizing the current status of GNP nanohybrid use for cancer theragnostics. Therefore, this review fulfills this gap in the literature by providing a critical analysis of the data available on the use of GNP nanohybrids for cancer treatment with a specific focus on synergistic approaches (i.e., triggered drug release, photothermal therapy, and radiotherapy). It also highlights some of the challenges that hinder the clinical translation of GNP hybrid nanostructures from bench to bedside. Future studies that could expedite the clinical progress of GNPs, as well as the future possibility of improving GNP nanohybrids for cancer theragnostics, are also summarized.

Tuning the drug multimodal release through a co-assembly strategy based on magnetic gels

Self-assembled short peptide-based gels are highly promising drug delivery systems. However, implementing a stimulus often requires screening different structures to obtain gels with suitable properties, and drugs might not be well encapsulated and/or cause undesirable effects on the gel's properties. To overcome this challenge, a new design approach is presented to modulate the release of doxorubicin as a model chemotherapeutic drug through the interplay of (di)phenylalanine-coated magnetic nanoparticles, PEGylated liposomes and doxorubicin co-assembly in dehydropeptide-based gels. The composites enable an enhancement of the gelation kinetics in a concentration-dependent manner, mainly through the use of PEGylated liposomes. The effect of the co-assembly of phenylalanine-coated nanoparticles with the hydrogel displays a concentration and size dependence. Finally, the integration of liposomes as doxorubicin storage units and of nanoparticles as composites that co-assemble with the gel matrix enables the tuneability of both passive and active doxorubicin release through a thermal, and a low-frequency alternating magnetic field-based trigger. In addition to the modulation of the gel properties, the functionalization with (di)phenylalanine improves the cytocompatibility of the nanoparticles. Hereby, this work paves a way for the development of peptide-based supramolecular systems for on-demand and controlled release of drugs.

Core-Shell Fe3O4@Au Nanorod-Loaded Gels for Tunable and Anisotropic Magneto- and Photothermia

Hyperthermia therapeutic treatments require improved multifunctional materials with tunable synergetic properties. Here, we report on the synthesis of Fe₃O₄@Au core-shell nanorods and their subsequent incorporation into an agarose hydrogel to obtain anisotropic magnetic and optical properties for magneto- and photothermal anisotropic transductions. Highly monodisperse ferrimagnetic Fe₃O₄ nanorods with tunable size were synthesized using a solvothermal method by varying the amount of hexadecylamine capping ligands. A gold shell was coated onto Fe₃O₄ nanorods by the intermediate formation of core-satellite structures and a subsequent controlled growth process, leading to an optical response variation from the visible to the near-infrared (NIR) region. The nanorods were oriented within an agarose hydrogel to fabricate free-standing anisotropic materials, providing a proof-of-concept for the applicability of these materials for anisotropic magneto- and photothermia applications. The strong gelling behavior upon cooling and shear-thinning behavior of agarose enable the fabrication of magnetically active continuous hydrogel filaments upon injection. These developed multifunctional nanohybrid materials represent a base for advanced sensing, biomedical, or actuator applications with an anisotropic response.

Smart/stimuli-responsive hydrogels: Cutting-edge platforms for tissue engineering and other biomedical applications

Recently, biomedicine and tissue regeneration have emerged as great advances that impacted the spectrum of healthcare. This left the door open for further improvement of their applications to revitalize the impaired tissues. Hence, restoring their functions. The implementation of therapeutic protocols that merge biomimetic scaffolds, bioactive molecules, and cells plays a pivotal role in this track. Smart/stimuli-responsive hydrogels are remarkable three-dimensional (3D) bioscaffolds intended for tissue engineering and other biomedical purposes. They can simulate the physicochemical, mechanical, and biological characters of the innate tissues. Also, they provide the aqueous conditions for cell growth, support 3D conformation, provide mechanical stability for the cells, and serve as potent delivery matrices for bioactive molecules. Many natural and artificial polymers were broadly utilized to design these intelligent platforms with novel advanced characteristics and tailored functionalities that fit such applications. In the present review, we highlighted the different types of smart/stimuli-responsive hydrogels with emphasis on their synthesis scheme. Besides, the mechanisms of their responsiveness to different stimuli were elaborated. Their potential for tissue engineering applications was discussed. Furthermore, their exploitation in other biomedical applications as targeted drug delivery, smart biosensors, actuators, 3D and 4D printing, and 3D cell culture were outlined. In addition, we threw light on smart self-healing hydrogels and their applications in biomedicine. Eventually, we presented their future perceptions in biomedical and tissue regeneration applications. Conclusively, current progress in the design of smart/stimuli-responsive hydrogels enhances their prospective to function as intelligent, and sophisticated systems in different biomedical applications.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Synthesis and Characterization of Fe0.8Mn0.2Fe2O4 Ferrite Nanoparticle with High Saturation Magnetization via the Surfactant Assisted Co-Precipitation

Manganese ferrite nanoparticles (MnFe₂O₄) were synthesized via surfactant-assisted co-precipitation, where sodium dodecyl sulfate (SDS) was used as the template to control particle size at various SDS concentrations. The substitutions of iron (II) (Fe²⁺) into the MnFe₂O₄ ferrite nanoparticles were carried out to obtain Fe₍₁-_x)Mn_xFe₂O₄, with various Mn²⁺: Fe²⁺ molar ratios. The synthesized ferrite nanoparticles were characterized by the Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), X-ray diffractometer (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), two-point probe, and vibrating sample magnetometer (VSM) techniques. The experimental Mn:Fe mole ratios of the Fe_(1-x)Mn_xFe₂O₄ ferrite nanoparticles were verified to be in agreement with the theoretical values. The synthesized MnFe₂O₄ and Fe_(1-x)Mn_xFe₂O₄ ferrite nanoparticles were of mixed spinel structures, with average spherical particle sizes between 17-22 nm, whereas the magnetite ferrite nanoparticles (Fe₃O₄) were of the inverse spinel structure. They showed soft ferromagnetic behavior. The synthesized Fe_0.8Mn_0.2Fe₂O₄ ferrite nanoparticle possessed the highest saturation magnetization of 88 emu/g relative to previously reported work to date.

Research Progress of Thermosensitive Hydrogel in Tumor Therapeutic

Compared with traditional tumor therapy strategies, hydrogel as a drug reservoir system can realize on-demand drug release and deep tissue penetration ability. It also exhibits great tumor-site retention to enhance the permeability and retention effect of tumor treatment. This can significantly overcome the drug's resistance and severe side effects. Inorganic/organic composite hydrogel has attracted wide attention due to its combined effects, enhancing therapeutic effects against various kinds of tumors. In situ injectable hydrogel can securely restrict the drugs in the lesion sites without leakage and guarantee better biosafety. Moreover, hydrogel possesses interconnected macropores which can provide enough space for nutrient transport, cellular activity, and cell-cell interactions. Thermal therapy is an effective strategy for tumor therapy due to its minimal invasiveness and high selectivity. Because the location temperature can be precisely controlled and helps avoid the risks of destroying the body's immune system and ablate normal cells, thermal therapy exhibits significant treatment outcomes. Nonetheless, when the cellular temperature reaches approximately 43 °C, it causes long-term cell inactivation. Based on these merits, thermosensitive hydrogel formulation with adaptive functions shows excellent efficacy, unlimited tissue penetration capacity, and few deleterious side effects. Furthermore, the thermosensitive hydrogel has unique physical properties under the external stimuli, which is the ideal drug delivery system for on-demand release in tumor treatment. This article will review the state of the thermosensitive hydrogel in clinic application for cancer therapy.

Nanoformulation Design Including MamC-Mediated Biomimetic Nanoparticles Allows the Simultaneous Application of Targeted Drug Delivery and Magnetic Hyperthermia

The design of novel nanomaterials that can be used as multifunctional platforms allowing the combination of therapies is gaining increased interest. Moreover, if this nanomaterial is intended for a targeted drug delivery, the use of several guidance methods to increase guidance efficiency is also crucial. Magnetic nanoparticles (MNPs) allow this combination of therapies and guidance strategies. In fact, MNPs can be used simultaneously as drug nanocarriers and magnetic hyperthermia agents and, moreover, they can be guided toward the target by an external magnetic field and by their functionalization with a specific probe. However, it is difficult to find a system based on MNPs that exhibits optimal conditions as a drug nanocarrier and as a magnetic hyperthermia agent. In this work, a novel nanoformulation is proposed to be used as a multifunctional platform that also allows dual complementary guidance. This nanoformulation is based on mixtures of inorganic magnetic nanoparticles (M) that have been shown to be optimal hyperthermia agents, and biomimetic magnetic nanoparticles (BM), that have been shown to be highly efficient drug nanocarriers. The presence of the magnetosome protein MamC at the surface of BM confers novel surface properties that allow for the efficient and stable functionalization of these nanoparticles without the need of further coating, with the release of the relevant molecule being pH-dependent, improved by magnetic hyperthermia. The BM are functionalized with Doxorubicin (DOXO) as a model drug and with an antibody that allows for dual guidance based on a magnetic field and on an antibody. The present study represents a proof of concept to optimize the nanoformulation composition in order to provide the best performance in terms of the magnetic hyperthermia agent and drug nanocarrier.

Electromagnetic radiation driving of volume changes in nanocomposites made of a thermosensitive hydrogel polymerized around conducting polymer nanoparticles

Polymeric nanocomposites were obtained by the formation of a thermosensitive hydrogel matrix around conducting polymer (CP) nanoparticles. The CP is able to absorb electromagnetic radiation which is converted into heat and induces the phase transition of the surrounding hydrogel. The method chosen to form the hydrogel is the free radical polymerization of a copolymer (N-isopropylacrylamide (NIPAM) and 2-acrylamide-2-methylpropano sulfonic acid (AMPS), PNIPAM-co-2% AMPS) in the presence of bisacrylamide as the crosslinker. The nanoparticles are polypyrrole nanospheres (PPy NP), polyaniline nanofibers (PANI NF), and polyaniline nanospheres (PANI NP). The morphology of the composites was studied using SEM microscopy and the percentage composition of each material was evaluated by thermogravimetric analysis (TGA). The swelling equilibrium capacity and rate are clearly affected by the nanoparticle shape and nature. However, the nanocomposites LCST are similar to that of the matrix. Upon RF irradiation, the three nanocomposites increase the temperature and reach the LCST after 320 seconds of irradiation (320 kJ). Upon MW application, the local temperature reaches the LCST after only 30 s (21 kJ), resulting in a MW more effective than RF to drive the transition. These results demonstrate that the proposed materials are useful as a remotely driven actuator.

A novel synthetic method of photothermally activated nanocomposites by in situ formation of hydrogel matrixes around dispersed conducting polymer nanoparticles is described.

Self-healing stable polymer hydrogel for pH regulated selective adsorption of dye and slow release of graphene quantum dots

Developing composite hydrogels with excellent self-healing ability and reasonable mechanical strength is extremely challenging. Herein, to overcome this difficulty, we identify the importance of balancing the ratio between the components of a composite hydrogel based on graphene oxide and poly(acrylic acid-acrylamide) [GOxAAM]. The gel exhibits enhanced mechanical strength, excellent self-healing ability, and extraordinary swelling capacity (a swelling ratio of 732) at room temperature and neutral pH. Further, the dye adsorption of the composite hydrogel has been investigated. The hydrogel could selectively adsorb organic cationic dyes (methylene blue vs. rhodamine B) from contaminated water with remarkable efficiency (90-95%). The kinetics investigation suggests that the dye adsorption on this composite hydrogel follows a pseudo-second-order model. The reusability of the hydrogel has been demonstrated by repeating the adsorption-desorption process over 10-14 cycles with almost identical results in the adsorption efficiency. Moreover, the hydrogel is utilized as a solvent-induced slow release source for graphene quantum dots (GQDs). The results taken together suggest that the (GOxAAM) composite gel can be a promising candidate for developing multifunctional gel materials.

Synthesis and Applications of Hydrogels in Cancer Therapy

Hydrogels are water-insoluble, hydrophilic, cross-linked, three-dimensional networks of polymer chains having the ability to swell and absorb water but do not dissolve in it, that comprise the major difference between gels and hydrogels. The mechanical strength, physical integrity and solubility are offered by the crosslinks. The different applications of hydrogels can be derived based on the methods of their synthesis, response to different stimuli, and their different kinds. Hydrogels are highly biocompatible and have properties similar to human tissues that make it suitable to be used in various biomedical applications, including drug delivery and tissue engineering. The role of hydrogels in cancer therapy is highly emerging in recent years. In the present review, we highlighted different methods of synthesis of hydrogels and their classification based on different parameters. Distinctive applications of hydrogels in the treatment of cancer are also discussed.

Magnetic Hydrogel with Optimally Adaptive Functions for Breast Cancer Recurrence Prevention

Engineering biocompatible hydrogels using functional nanoparticles has attracted considerable attention because of their uniquely appealing cooperative effects that can enable multimodality imaging and treatment with improved efficacy against serious diseases. However, the effects of high-content nanoparticle dopants on the rheological properties of hydrogels frequently lead to an unsatisfactory therapeutic result, which is particularly notable in the design of magnetic hydrogel formulations for cancer therapy. Herein is reported a novel magnetic hydrogel functionalized by ferromagnetic vortex-domain iron oxide (FVIOs) with optimally adaptive functions for prevention of breast cancer recurrence. The FVIOs can perfectly incorporate into the dynamic hydrogel networks with an extremely low concentration (0.6 mg mL^-1 ), 17 times lower than that of conventional superparamagnetic iron oxide nanoparticles with sufficient heating capacity. Such magnetic hydrogels exhibit high inductive heating and remarkable rheological properties simultaneously. Moreover, the self-healing, self-conformal ability, controlled release of loaded doxorubicin, biodegradation, and pH-responsiveness of the magnetic hydrogel project their efficient sustainable therapeutic ability. In vivo postoperative treatment has further demonstrated the high efficacy of FVIO-based magnetic hydrogels, as evidenced by the significant suppression of the local tumor recurrences compared to chemotherapy or hyperthermia alone. This unique magnetic hydrogel formulation with optimally adaptive functions shows strong potential in preventing relapses of various cancers.

Evolution of Magnetic Hyperthermia for Glioblastoma Multiforme Therapy

Glioblastoma multiforme (GBM) is the most common and aggressive type of glial tumor, and despite many recent advances, its prognosis remains dismal. Hence, new therapeutic approaches for successful GBM treatment are urgently required. Magnetic hyperthermia-mediated cancer therapy (MHCT), which is based on heating the tumor tissues using magnetic nanoparticles on exposure to an alternating magnetic field (AMF), has shown promising results in the preclinical studies conducted so far. The aim of this Review is to evaluate the progression of MHCT for GBM treatment and to determine its effectiveness on the treatment either alone or in combination with other adjuvant therapies. The preclinical studies presented MHCT as an effective treatment module for the reduction of tumor cell growth and increase in survival of the tumor models used. Over the years, much research has been done to prove MHCT alone as the missing notch for successful GBM therapy. However, very few combinatorial studies have been reported. Some of the clinical studies carried out so far depicted that MHCT could be applied safely while possessing minimal side effects. Finally, we believe that, in the future, advancements in magnetic nanosystems might contribute toward establishing MHCT as a potential treatment tool for glioma therapy.

Controlling deformations of gel-based composites by electromagnetic signals within the GHz frequency range

Using theoretical and computational modeling, we focus on dynamics of gels filled with uniformly dispersed ferromagnetic nanoparticles subjected to electromagnetic (EM) irradiation within the GHz frequency range. As a polymer matrix, we choose poly(N-isopropylacrylamide) gel, which has a low critical solution temperature and shrinks upon heating. When these composites are irradiated with a frequency close to the Ferro-Magnetic Resonance (FMR) frequency, the heating rate increases dramatically. The energy dissipation of EM signals within the magnetic nanoparticles results in the heating of the gel matrix. We show that the EM signal causes volume phase transitions, leading to large deformations of the sample for a range of system parameters. We propose a model that accounts for the dynamic coupling between the elastodynamics of the polymer gel and the FMR heating of magnetic nanoparticles. This coupling is nonlinear: when the system is heated, the gel shrinks during the volume phase transition, and the particle concentration increases, which in turn results in an increase of the heating rates as long as the concentration of nanoparticles does not exceed a critical value. We show that the system exhibits high selectivity to the frequency of the incident EM signal and can result in a large mechanical feedback in response to a small change in the applied signal. These results suggest the design of a new class of soft active gel-based materials remotely controlled by low power EM signals within the GHz frequency range.

Poly(N-isopropylacrylamide) and Copolymers: A Review on Recent Progresses in Biomedical Applications

The innate ability of poly(N-isopropylacrylamide) (PNIPAAm) thermo-responsive hydrogel to copolymerize and to graft synthetic polymers and biomolecules, in conjunction with the highly controlled methods of radical polymerization which are now available, have expedited the widespread number of papers published in the last decade-especially in the biomedical field. Therefore, PNIPAAm-based hydrogels are extensively investigated for applications on the controlled delivery of active molecules, in self-healing materials, tissue engineering, regenerative medicine, or in the smart encapsulation of cells. The most promising polymers for biodegradability enhancement of PNIPAAm hydrogels are probably poly(ethylene glycol) (PEG) and/or poly(ε-caprolactone) (PCL), whereas the biocompatibility is mostly achieved with biopolymers. Ultimately, advances in three-dimensional bioprinting technology would contribute to the design of new devices and medical tools with thermal stimuli response needs, fabricated with PNIPAAm hydrogels.

Recent Advances in Hydrogel-Based Drug Delivery for Melanoma Cancer Therapy: A Mini Review

The purpose of this study is to describe some of the latest advances in using hydrogels for cancer melanoma therapy. Hydrogel formulations of polymeric material from natural or synthetic sources combined with therapeutic agents have gained great attention in the recent years for treating various maladies. These formulations can be categorized according to the strategies that induce cancer cell death in melanoma. First of all, we should note that these formulations can only play a supporting role that releases bioactive agents against cancer cells rather than the main role. This strategy involves delivering the drug via transdermal pathways, resulting in the death of cancerous cells. Another strategy utilizes magnetic gel composites to combat melanoma via hyperthermia therapy. This review discusses both transdermal and hyperthermia therapies and the recent advances that have occurred in the field.

Facile fabrication of a magnetic self-healing poly(vinyl alcohol) composite hydrogel

This study proposes a simple method to fabricate a magnetic self-healing poly(vinyl alcohol) (ms-PVA) composite hydrogel.