Development and Potential Theranostic Applications of a Self-Assembled Hybrid of Magnetic Nanoparticle Clusters with Polysaccharide Nanogels

Photodynamic therapy using hybrid nanoparticles comprising of upconversion nanoparticles and chlorin e6-bearing pullulan

With its minimal invasiveness, photodynamic therapy (PDT) is considered one of the most elegant modalities in cancer treatment. In this study, a facile hybrid nanoparticle was developed, composed of upconversion nanoparticles and chlorin e6-bearing pullulan, which can serve as a photosensitizer activated by a near-infrared red laser. Cell death induction in cancer cells was achieved through energy transfer from the near-infrared red laser emitted by the upconversion nanoparticles to chlorin e6. The therapeutic efficacy of our hybrid system surpassed that of the clinically available photosensitizer, Photofrin, and hybrid liposomes comprising upconversion nanoparticles and chlorin e6 were employed as control. Accumulation of our system in tumor tissue in tumor xenograft mice was primarily achieved through the enhanced permeability and retention (EPR) effect. The administered hybrids were excreted from each organ within 21 days after administration, minimizing the risk of undesirable side effects. Notably, our system exhibited 400 times higher PDT activity in tumor-bearing mice compared to the control groups. It also effectively inhibited metastasis.

Theranostic nanogels: multifunctional agents for simultaneous therapeutic delivery and diagnostic imaging

In recent years, there has been a growing interest in multifunctional theranostic agents capable of delivering therapeutic payloads while facilitating simultaneous diagnostic imaging of diseased sites. This approach offers a comprehensive strategy particularly valuable in dynamically evolving diseases like cancer, where combining therapy and diagnostics provides crucial insights for treatment planning. Nanoscale platforms, specifically nanogels, have emerged as promising candidates due to their stability, tunability, and multifunctionality as carriers. As a well-studied subgroup of soft polymeric nanoparticles, nanogels exhibit inherent advantages due to their size and chemical compositions, allowing for passive and active targeting of diseased tissues. Moreover, nanogels loaded with therapeutic and diagnostic agents can be designed to respond to specific stimuli at the disease site, enhancing their efficacy and specificity. This capability enables fine-tuning of theranostic platforms, garnering significant clinical interest as they can be tailored for personalized treatments. The ability to monitor tumor progression in response to treatment facilitates the adaptation of therapies according to individual patient responses, highlighting the importance of designing theranostic platforms to guide clinicians in making informed treatment decisions. Consequently, the integration of therapy and diagnostics using theranostic platforms continues to advance, offering intelligent solutions to address the challenges of complex diseases such as cancer. In this context, nanogels capable of delivering therapeutic payloads and simultaneously armed with diagnostic modalities have emerged as an attractive theranostic platform. This review focuses on advances made toward the fabrication and utilization of theranostic nanogels by highlighting examples from recent literature where their performances through a combination of therapeutic agents and imaging methods have been evaluated.

Reversible conjugation of biomembrane vesicles with magnetic nanoparticles using a self-assembled nanogel interface: single particle analysis using imaging flow cytometry

Nanoscale biomembrane vesicles such as liposomes and extracellular vesicles are promising materials for therapeutic delivery applications. However, modification processes that disrupt the biomembrane affect the performance of these systems. Non-covalent functionalization approaches that are facile and easily reversed by environmental triggers are therefore being widely investigated. In this study, liposomes were successfully hybridized with magnetic iron oxide particles using a cholesterol-modified pullulan nanogel interface. Both the magnetic nanoparticles and the hydrophobic core of the lipid bilayer interacted with the hydrophobic cholesteryl moieties, resulting in stable hybrids after simple mixing. Single particle analysis by imaging flow cytometry showed that the hybrid particles interacted in solution. Calcein loaded liposomes were not disrupted by the hybridization, showing that conjugation did not affect membrane stability. The hybrids could be magnetically separated and showed significantly enhanced uptake by HeLa cells when a magnetic field was applied. Differential scanning calorimetry revealed that the hybridization mechanism involved hydrophobic cholesteryl inserting into the biomembrane. Furthermore, exposure of the hybrids to fetal bovine serum proteins reversed the hybridization in a concentration dependent manner, indicating that the interaction was both reversible and controllable. This is the first example of reversible inorganic material conjugation with a biomembrane that has been confirmed by single particle analysis. Both the magnetic nanogel/liposome hybrids and the imaging flow cytometry analysis method have the potential to significantly contribute to therapeutic delivery and nanomaterial development.

Flowability of Gel-Matrix and Magnetorheological Response for Carrageenan Magnetic Hydrogels

The relationship between rheological features in the absence of a magnetic field and magnetic response was investigated for κ-carrageenan magnetic hydrogels containing carbonyl iron particles. The concentration of carrageenan was varied from 1.0 to 5.0 wt%, while the concentration of carbonyl iron was kept at 70 wt%. The magnetic response revealed that the change in storage modulus ΔG' decreased inversely proportional to the carrageenan concentration. A characteristic strain γ1 where G' equals to G″ was seen in a strain range of 10-3. It was found that ΔG' was inversely proportional to the characteristic stress at γ1. Another characteristic strain γ2 where the loss tangent significantly increased was also analyzed. Similar to the behavior of γ1, ΔG' was inversely proportional to γ2. The characteristic stresses at γ1 and γ2 were distributed at 80-720 Pa and 40-310 Pa, respectively. It was revealed that a giant magnetorheology higher than 1 MPa can be observed when the characteristic stresses at γ1 and γ2 are below approximately 240 Pa and 110 Pa, respectively.

Magnetically Navigated Protein Transduction In Vivo using Iron Oxide-Nanogel Chaperone Hybrid

Systems for "protein transduction," intracellular delivery of functional proteins, are needed to address deliverability challenges of protein therapeutics. However, in vivo protein transduction remains challenging because of instability in serum, extracellular protease digestion and rapid excretion from the bloodstream. Here, a magnetically guided in vivo protein transduction using magnetic nanogel chaperone (MC) composed of iron oxide nanoparticles and a polysaccharide nanogel, a protein carrier inspired by "catch and release" mechanisms of molecular chaperones is demonstrated. The MC system enables efficient delivery of anti-cancer proteins, saporin and RNaseA, into cultured tumor lines and inhibits cell proliferation, mainly via apoptosis. Magnetic in vivo protein transduction via intravenous whole body administration is demonstrated in a fibrosarcoma model. By in vivo optical imaging, MC accumulated in tumor tissues under magnetic field three times more than without irradiation. With subcutaneous injection, saporin is delivered by MC to the cytoplasm in magnetically targeted tissues. In an oral cancer model, MC-delivered magnetically targeted saporin decreased tumor volume without significant body weight changes and no regrowth of tumor at 3 months after complete regression. Protein transduction with MC shows promise for cancer therapeutics and, potentially, for regenerative medicine and other biomedical applications.

Particle Size in Secondary Particle and Magnetic Response for Carrageenan Magnetic Hydrogels

The relation between the number of magnetic particles and the change in storage modulus induced by a magnetic field was investigated for weak hydrogels containing carbonyl iron, iron oxide, and barium ferrite particles with different diameters in primary particles while maintaining the magnetization of magnetic particles. The change in storage modulus exhibited a power dependency against the number of magnetic particles, which was nearly independent of the magnetic particles. The change in storage modulus was successfully scaled by the reduced number of magnetic particles using the diameter of secondary particles. Microphotographs revealed that iron oxide and barium ferrite particles form aggregations while carbonyl iron particles are well dispersed in carrageenan gels. The diameter of secondary particles determined by a relation between the change in storage modulus and the reduced number of magnetic particles showed similar values with those observed in microphotographs.

Smart Organic-Inorganic Nanogels for Activatable Theranostics

Intelligent polymeric nanogels, with the rationally designed stimuli-responsive drug delivery and controlled drug release, have attracted considerable attention as an ideal nanoplatform for activatable therapy. On the other hand, functional inorganic nanomaterials are widely used as medical imaging agents due to their unique magnetic or optical properties. The construction of stimuli-responsive polymeric nanogels incorporating with functional inorganic nanomaterials inherits the excellent properties of both polymers and inorganic nanomaterials, consequently, the resulted organic-inorganic hybrid nanogels naturally exhibit stimuli-responsive multi-functionalities for both imaging and therapy. In this review, we summarize the recent advances of stimuli-responsive organic-inorganic hybrid nanogels. Firstly, we discuss the physical and chemical methods thus far developed for the integration of polymeric nanogels and inorganic nanomaterials, and then we show the typical examples of activatable theranostic applications using organic-inorganic hybrid nanogels. In the end, the existing challenges and future directions are briefly discussed.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

Nanogels: An overview of properties, biomedical applications and obstacles to clinical translation

Nanogels have emerged as a versatile hydrophilic platform for encapsulation of guest molecules with a capability to respond to external stimuli that can be used for a multitude of applications. These are soft materials capable of holding small molecular therapeutics, biomacromolecules, and inorganic nanoparticles within their crosslinked networks, which allows them to find applications for therapy as well as imaging of a variety of disease conditions. Their stimuli-responsive behavior can be easily controlled by selection of constituent polymer and crosslinker components to achieve a desired response at the site of action, which imparts nanogels the ability to participate actively in the intended function of the carrier system rather than being passive carriers of their cargo. These properties not only enhance the functionality of the carrier system but also help in overcoming many of the challenges associated with the delivery of cargo molecules, and this review aims to highlight the distinct and unique capabilities of nanogels as carrier systems for the delivery of an array of cargo molecules over other nanomaterials. Despite their obvious usefulness, nanogels are still not a commonplace occurrence in clinical practice. We have also made an attempt to highlight some of the major challenges that need to be overcome to advance nanogels further in the field of biomedical applications.

Magnetically Guided Protein Transduction by Hybrid Nanogel Chaperones with Iron Oxide Nanoparticles

Protein pharmaceuticals show great therapeutic promise, but effective intracellular delivery remains challenging. To address the need for efficient protein transduction systems, we used a magnetic nanogel chaperone (MC): a hybrid of a polysaccharide nanogel, a protein carrier with molecular chaperone-like properties, and iron oxide nanoparticles, enabling magnetically guided delivery. The MC complexed with model proteins, such as BSA and insulin, and was not cytotoxic. Cargo proteins were delivered to the target HeLa cell cytosol using a magnetic field to promote movement of the protein complex toward the cells. Delivery was confirmed by fluorescence microscopy and flow cytometry. Delivered β-galactosidase, inactive within the MC complex, became enzymatically active within cells to convert a prodrug. Thus, cargo proteins were released from MC complexes through exchange interactions with cytosolic proteins. The MC is a promising tool for realizing the therapeutic potential of proteins.

In Situ Synthesis of Magnetic Field-Responsive Hemicellulose Hydrogels for Drug Delivery

A one-pot synthetic methodology for fabricating stimuli-responsive hemicellulose-based hydrogels was developed that consists of the in situ formation of magnetic iron oxide (Fe₃O₄) nanoparticles during the covalent cross-linking of O-acetyl-galactoglucomannan (AcGGM). The Fe₃O₄ nanoparticle content controlled the thermal stability, macrostructure, swelling behavior, and magnetization of the hybrid hydrogels. In addition, the magnetic field-responsive hemicellulose hydrogels (MFRHHs) exhibited excellent adsorption and controlled release profiles with bovine serum albumin (BSA) as the model drug. Therefore, the MFRHHs have great potential to be utilized in the biomedical field for tissue engineering applications, controlled drug delivery, and magnetically assisted bioseparation. Magnetic field-responsive hemicellulose hydrogels, prepared using a straightforward one-step process, expand the applications of biomass-derived polysaccharides by combining the renewability of hemicellulose and the magnetism of Fe₃O₄ nanoparticles.

Controlled radical polymerization of styrene with magnetic iron oxides prepared through hydrothermal, bioinspired, and bacterial processes

Controlled/living radical polymerization of styrene proceeded with the use of magnetic iron oxide (Fe₃O₄) prepared through various processes.