Theranostics Based on Magnetic Nanoparticles and Polymers: Intelligent Design for Efficient Diagnostics and Therapy

Key Insights on the Classification and Theranostic Applications of Magnetic Resonance Imaging Contrast Agents

Magnetic resonance imaging (MRI) is a non-invasive molecular imaging tool being extensively employed in clinical and biomedical research for the detection of a broad spectrum of diseases. This technique offers remarkable spatial resolution, good tissue penetration and a high soft tissue contrast. Contrast agents (CAs) have been regularly used in MRI tests to enhance the resolution of MR images and to visualize the diseased sites in the body. In the past years, considerable efforts have been devoted towards developing new theranostic MRI agents that can be tailored to integrate the targeting and therapeutic functions in a single agent. In this review, we have underlined the role of the MRI CAs in the developing field of 'theranostics' and their recent applications in the combined imaging and therapy of different types of tumors. In addition, this review also outlines the different categories of MRI CAs and their comprehensive classification based on different criteria such as chemical composition, relaxation mechanism and biodistribution with clinically relevant examples.

Theranostics: a multifaceted approach utilizing nano-biomaterials

Biomaterials play a vital role in targeting therapeutics. Over the years, several biomaterials have gained wide attention in the treatment and diagnosis of diseases. Scientists are trying to make more personalized treatments for different diseases, as well as discovering novel single agents that can be used for prognosis, medication administration, and keeping track of how a treatment works. Theranostics based on nano-biomaterials have higher sensitivity and specificity for disease management than conventional techniques. This review provides a concise overview of various biomaterials, including carbon-based materials like fullerenes, graphene, carbon nanotubes (CNTs), and carbon nanofibers, and their involvement in theranostics of different diseases. In addition, the involvement of imaging techniques for theranostics applications was overviewed. Theranostics is an emerging strategy that has great potential for enhancing the accuracy and efficacy of medicinal interventions. Despite the presence of obstacles such as disease heterogeneity, toxicity, reproducibility, uniformity, upscaling production, and regulatory hurdles, the field of medical research and development has great promise due to its ability to provide patients with personalised care, facilitate early identification, and enable focused treatment.

Polypropylene sulphide coating on magnetic nanoparticles as a novel platform for excellent biocompatible, stimuli-responsive smart magnetic nanocarriers for cancer therapeutics

Magnetic nanoparticle (MNP) delivery systems are promising for targeted drug delivery, imaging, and chemo-hyperthermia of cancer; however, their uses remain limited primarily due to their toxicity associated with reactive oxygen species (ROS) generation, targeted delivery, and biodegradation. Attempts employing polymer coatings to minimize the toxicity, along with other challenges, have had limited success. We designed a novel yet generic 'one-for-all' polypropylene sulphide (PPS) coated magnetic nano-delivery system (80 ± 15 nm) as a multi-faceted approach for significant biocompatibility improvement, loading of multiple drugs, ROS-responsive delivery, and combined chemo-hyperthermia therapy for biomedical applications. Three distinct MNP systems (15 ± 1 nm) were fabricated, coated with PPS polymer, and investigated to validate our hypothesis and design. Simultaneous degradation of MNPs and PPS coatings with ROS-scavenging characteristics boosted the biocompatibility of MNPs 2-3 times towards non-cancerous fibroblasts (NIH3T3) and human epithelial cells (HEK293). In an alternating magnetic field, PPS-MNPs (MnFe) had the strongest heating characteristics (SAR value of 240 W g^-1). PPS-MNP drug-loaded NPs were efficiently internalised into cells and released 80% of the drugs under tumor microenvironment-mimicking (pH 5-7, ROS) conditions, and demonstrated effective chemo-hyperthermia (45 °C) application for breast cancer cells with 95% cell death in combined treatment vs. 55% and 30% cell death in only hyperthermia and chemotherapy respectively.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Revealing the nature of optical activity in carbon dots produced from different chiral precursor molecules

Carbon dots (CDs) are light-emitting nanoparticles that show great promise for applications in biology and medicine due to the ease of fabrication, biocompatibility, and attractive optical properties. Optical chirality, on the other hand, is an intrinsic feature inherent in many objects in nature, and it can play an important role in the formation of artificial complexes based on CDs that are implemented for enantiomer recognition, site-specific bonding, etc. We employed a one-step hydrothermal synthesis to produce chiral CDs from the commonly used precursors citric acid and ethylenediamine together with a set of different chiral precursors, namely, L-isomers of cysteine, glutathione, phenylglycine, and tryptophan. The resulting CDs consisted of O,N-doped (and also S-doped, in some cases) carbonized cores with surfaces rich in amide and hydroxyl groups; they exhibited high photoluminescence quantum yields reaching 57%, chiral optical signals in the UV and visible spectral regions, and two-photon absorption. Chiral signals of CDs were rather complex and originated from a combination of the chiral precursors attached to the CD surface, hybridization of lower-energy levels of chiral chromophores formed within CDs, and intrinsic chirality of the CD cores. Using DFT analysis, we showed how incorporation of the chiral precursors at the optical centers induced a strong response in their circular dichroism spectra. The optical characteristics of these CDs, which can easily be dispersed in solvents of different polarities, remained stable during pH changes in the environment and after UV exposure for more than 400 min, which opens a wide range of bio-applications.

Superparamagnetic iron oxide nanoparticles for magnetic hyperthermia: Recent advancements, molecular effects, and future directions in the omics era

Superparamagnetic iron oxide nanoparticles have attracted attention in the biomedical field thanks to their ability to prompt hyperthermia in response to an alternated magnetic field. Hyperthermia is well-known for inducing...

Development of Polymer-Based Nanoformulations for Glioblastoma Brain Cancer Therapy and Diagnosis: An Update

Brain cancers, mainly high-grade gliomas/glioblastoma, are characterized by uncontrolled proliferation and recurrence with an extremely poor prognosis. Despite various conventional treatment strategies, viz., resection, chemotherapy, and radiotherapy, the outcomes are still inefficient against glioblastoma. The blood–brain barrier is one of the major issues that affect the effective delivery of drugs to the brain for glioblastoma therapy. Various studies have been undergone in order to find novel therapeutic strategies for effective glioblastoma treatment. The advent of nanodiagnostics, i.e., imaging combined with therapies termed as nanotheranostics, can improve the therapeutic efficacy by determining the extent of tumour distribution prior to surgery as well as the response to a treatment regimen after surgery. Polymer nanoparticles gain tremendous attention due to their versatile nature for modification that allows precise targeting, diagnosis, and drug delivery to the brain with minimal adverse side effects. This review addresses the advancements of polymer nanoparticles in drug delivery, diagnosis, and therapy against brain cancer. The mechanisms of drug delivery to the brain of these systems and their future directions are also briefly discussed.

A Co-delivery System Based on a Dimeric Prodrug and Star-Shaped Polymeric Prodrug Micelles for Drug Delivery

Chemotherapy is one of the commonly used therapies for the treatment of malignant tumors. Insufficient drug-loading capacity is the major challenge for polymeric micelle-based drug delivery systems of chemotherapy. Here, the redox-responsive star-shaped polymeric prodrug (PSSP) and the dimeric prodrug of paclitaxel (PTX) were prepared. Then the dimeric prodrug of PTX (diPTX, diP) was loaded into the core of the star-shaped polymeric prodrug micelles of PSSP by hydrophobic interaction forming the redox-responsive prodrug micelles of diPTX@PSSP for intracellular drug release in tumor cells. The hydrodynamic diameter of diPTX@PSSP nanoparticles was 114.3 nm ± 2.1 (PDI = 0.219 ± 0.016), and the micelles had long-term colloidal stability and the drug-loading content (DLC) of diPTX and PTX is 16.7 and 46.9%, respectively. The prepared micelles could broke under the reductive microenvironment within tumor cells, as a result, the dimeric prodrug of diP and polymeric prodrug micelles of PSSP were rapidly disassembled, leading to the rapid release of intracellular drugs. In vitro release studies showed that under the condition of reduced glutathione (GSH) (10 mM), the release of PTX was significantly accelerated with approximately 86.6% released within 21 h, and the released PTX in cytoplasm could promote the disintegration of microtubules and induce cell apoptosis. These results indicated that the new type of this reduction-sensitive nanodrug delivery system based on dimeric prodrug@polymeric prodrug micelles would be a promising technology in chemotherapy.

A Theoretical Analysis of Magnetic Particle Alignment in External Magnetic Fields Affected by Viscosity and Brownian Motion

The interaction of an external magnetic field with magnetic objects affects their response and is a fundamental property for many biomedical applications, including magnetic resonance and particle imaging, electromagnetic hyperthermia, and magnetic targeting and separation. Magnetic alignment and relaxation are widely studied in the context of these applications. In this study, we theoretically investigate the alignment dynamics of a rotational magnetic particle as an inverse process to Brownian relaxation. The selected external magnetic flux density ranges from 5μT to 5T. We found that the viscous torque for arbitrary rotating particles with a history term due to the inertia and friction of the surrounding ambient water has a significant effect in strong magnetic fields (range 1–5T). In this range, oscillatory behavior due to the inertial torque of the particle also occurs, and the stochastic Brownian torque diminishes. In contrast, for weak fields (range 5–50μT), the history term of the viscous torque and the inertial torque can be neglected, and the stochastic Brownian torque induced by random collisions of the surrounding fluid molecules becomes dominant. These results contribute to a better understanding of the molecular mechanisms of magnetic particle alignment in external magnetic fields and have important implications in a variety of biomedical applications.

Polymeric nanocapsules: A review on design and production methods for pharmaceutical purpose

Polymeric nanocapsules have extensive application potential in medical, biological, and pharmaceutical fields, and, therefore, much research has been dedicated to their production. Indeed, production protocols and the materials used are decisive for obtaining the desired nanocapsules characteristics and biological performance. In addition to that, several technological strategies have been developed in the last decade to improve processing techniques and form more valuable nanocapsules. This review provides a guide to current methods for developing polymeric nanocapsules, reporting aspects to be considered when choosing appropriate materials, and discussing different ways to produce nanocapsules for superior performances.

Modified Indulines: From Dyestuffs to In Vivo Theranostic Agents

The efficient, versatile, and straightforward synthesis of the first N-alkyl analogues of induline 3B (8a and 8b) is reported. Thanks to the introduction of lipophilic substituents and their attractive photophysical properties (far-red emission and production of singlet oxygen), phenazinium 8b can be used as a theranostic agent and shows, at very low concentrations (100 nM), a remarkable ability to (i) image cells and zebrafish embryos with high quality under both mono- (514 nm) and biphotonic (790 and 810 nm) excitations, (ii) efficiently and quickly penetrate cancer cells rather than healthy fibroblasts, and (iii) induce a total or almost total cancer cell death in vitro and in vivo after illumination (λ_exc = 540-560 nm). The molecular structure of 8b is based on a triamino-phenazinium core only, with no need for additional components, highlighting the emergence of a minimalistic and versatile class of fluorescent probes for targeted photodynamic cancer therapy.

Hetero-Trifunctional Malonate-Based Nanotheranostic System for Targeted Breast Cancer Therapy

Designing multifunctional linkers is crucial for tricomponent theranostic targeted nanomedicine development as they are essential to enrich polymeric systems with different functional moieties. Herein, we have obtained a hetero-trifunctional linker from malonic acid and demonstrated its implication as an amphiphilic targeted nanotheranostic system (CB DX UN PG FL). We synthesized it with varying hydrophilic segment to fine-tune the hydrophobic/hydrophilic ratio to optimize its self-assembly. pH-responsive hydrazone-linked doxorubicin was conjugated to the backbone (UN PG FL) containing folate as a targeting ligand. Cobalt carbonyl complex was used for T₂-weighted magnetic resonance imaging (MRI). Electron micrographs of optimized molecule CB DX UN PG_(4 kDa) FL in an aqueous system have demonstrated about 50-60 nm-sized uniform micelles. The relaxivity study and the one-dimensional (1D) imaging experiments clearly revealed the effect of the nanotheranostics system on transverse relaxation (T₂) of water molecules, which validated the system as a T₂-weighted MRI contrast agent. The detailed in vitro biological studies validated the targeted delivery and anticancer potential of CB DX UN PG_(4 kDa) FL. Combining the data on transverse relaxation, folate mediated uptake, and anticancer activity, the designed molecule will have a significant impact on the development of targeted theranostic.

Magnetic Nanoparticle-Based Drug Delivery Approaches for Preventing and Treating Biofilms in Cystic Fibrosis

Biofilm-associated infections pose a huge burden on healthcare systems worldwide, with recurrent lung infections occurring due to the persistence of biofilm bacteria populations. In cystic fibrosis (CF), thick viscous mucus acts not only as a physical barrier, but also serves as a nidus for infection. Increased antibiotic resistance in the recent years indicates that current therapeutic strategies aimed at biofilm-associated infections are “failing”, emphasizing the need to develop new and improved drug delivery systems with higher efficacy and efficiency. Magnetic nanoparticles (MNPs) have unique and favourable properties encompassing biocompatibility, biodegradability, magnetic and heat-mediated characteristics, making them suitable drug carriers. Additionally, an external magnetic force can be applied to enhance drug delivery to target sites, acting as “nano-knives”, cutting through the bacterial biofilm layer and characteristically thick mucus in CF. In this review, we explore the multidisciplinary approach of using current and novel MNPs as vehicles of drug delivery. Although many of these offer exciting prospects for future biofilm therapeutics, there are also major challenges of this emerging field that need to be addressed.