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In the present work, an attempt was made to engineer a mesoporous silica coated magnetic nanoparticles (MNF@mSiO 2 ) for twin mode contrast in magnetic resonance imaging (MRI) with reduced toxicity. Superparamagnetic manganese ferrite nanoparticles were synthesized with variable mesoporous silica shell thickness to control the water molecules interacting with metal oxide core. 178 nm was the optimum hydrodynamic diameter of mesoporous ferrite core-shell nanoparticles that showed maximum longitudinal relaxation time (T1) and transverse relaxation time (T2) in MRI due to the storage of water molecules in mesoporous silica coating. Besides the major role of mesoporous silica in controlling relaxivity, mesoporous silica shell also reduces the toxicity and enhances the bioavailability of superparamagnetic manganese ferrite nanoparticles. The in vitro toxicity assessment using HepG2 liver carcinoma cells shows that the mesoporous silica coating over ferrite nanoparticles could exert less toxicity compared to the uncoated particle.

Carbon-decorated ferrite nanodots (MNF@Cs) have been enhanced with superparamagnetism and higher fluorescence quantum yield by encapsulation with an alginate derivative to create a cost-effective and less toxic multimodal contrast agent for replacing the conventional heavy metal Gd-containing contrast agent used in MR imaging. The novel surface-engineered particles (MNF@C-OSAs), devoid of labels, can simultaneously provide both longitudinal and transverse relaxation-based magnetic resonance imaging (MRI) and fluorescence emission. According to the findings of in vitro studies, the calculated molar relaxivities and the molar radiant efficiencies are indicative of the multimodal efficacy of MNF@C-OSA as compared with MNF@C particles and conventional contrast agents used in medical imaging. MNF@C-OSAs were shown to be significantly biocompatible and negligibly toxic when assessed against A549 cells and zebrafish embryos, indicating their potential for use as theranostic agents. [ABSTRACT FROM AUTHOR]

The advancements in nanotechnology have quickly developed a new subject with vast applications of nanostructured materials in medicine and pharmaceuticals. The enormous surface-to-volume ratio, ease of surface modification, outstanding biocompatibility, and, in the case of mesoporous nanoparticles, the tunable pore size make the silica nanoparticles (SNPs) a promising candidate for nano-based medical applications. The preparation of SNPs and their contemporary usage as drug carriers, contrast agents for imaging, carrier of photosensitizers (PS) in photodynamic, as well as photothermal treatments are intensely discussed in this review. Furthermore, the potential harmful responses of silica nanoparticles are reviewed using data obtained from in vitro and in vivo experiments conducted by several studies. Moreover, we showcase the engineering of SNPs for the theranostic applications that can address several intrinsic limitations of conventional therapeutics and diagnostics. In the end, a personal perspective was outlined to state SNPs' current status and future directions, focusing on SNPs' significant potentiality and opportunities. [ABSTRACT FROM AUTHOR]

Biological events can be mapped in real-time using fluorescent images at high spatial resolution through the use of a powerful tool called fluorescence, and it is necessary to have ultra-bright fluorescent probes. The detrimental effects associated with the existing fluorescence imaging probes and contrast agents are the primary reason behind the greater involvement of nanotechnology. Developing advanced particles at the molecular and supramolecular levels is the only way to address the constraints underlying the current scenario. Nanosized structures dominate in multiple fields, especially in nanotheranostics, due to their higher quantum yield, negligible photobleaching, excellent biocompatibility, tunable optical properties, and improved circulation half-lives. Nanofluorophores, which are nanoparticles encapsulated or doped with fluorescent dyes, play a crucial role in fluorescence-based imaging modality by providing noninvasive realtime monitoring of the inner machinery of the anatomical and cellular structures. In addition to fluorescent inorganic and organic nanoparticles, there are labeled hydrophilic and hydrophobic nanostructures, semiconducting dots, carbon dots, as well as upconversion nanomaterials, etc., which are widely used in fluorescent imaging. A comprehensive literature survey has been provided in this review since intense studies are needed to clear the preclinic stage, thus opening up opportunities for future biomedical applications. [ABSTRACT FROM AUTHOR]

The domain of Janus nanoparticles (JNPs) has seen a surge in research and development during the last decade. JNPs are anisotropic composite innovations with remarkable characteristics that depict a peculiar class of particles, which integrate the features and functions of multiple materials into a single unit. Janus particles are superior prospects for several high-end applications due to their possible modifications by "click chemistry". JNPs offer new possibilities by combining the features of components. Janus nanoparticles can pack multiple pharmaceuticals and imaging contrast agents simultaneously since they have a distinct chemical configuration on different sides. As a result, they become ideal for administration and bioimaging at once. They have sparked interest due to their exceptional architecture and their potential implications in science and engineering, biological application, and most notably, theranostics. The emphasis of this review is on the latest advancement in the fabrication and implementation of innovative Janus nanoparticles, along with their spectacular performance in therapeutic delivery applications. [ABSTRACT FROM AUTHOR]

Medical imaging is currently revolutionizing the diagnosis and treatment of a variety of diseases. Several imaging modalities have been developed based on advances in science and engineering. The impact of these imaging tools has been further improved with the advent of various modern chemistries, leading to the development of contrast agents that serve further to localize the detection of diseased tissues. Several researchers are recently involved in engineering contrast agents that can generate contrast differences between tissues in multiple imaging modalities, enabling cross-referenced determination of anomalies. To establish these multimodal imaging agents, nanovectors have gained significance due to their key physicochemical properties. The major focus of this review is on the engineering strategies of nanovectors for multimodal medical imaging. The review conceives the basic principles, major parameters, and limitations of imaging modalities, namely, magnetic resonance imaging (MRI), computed tomography (CT), and fluorescence imaging at the beginning. Drawbacks of traditional contrast agents and the demand for new contrast agents are established. The importance of multimodal imaging and the need for a single contrast agent for these imaging applications are elaborated. Finally, the advantages, limitations, and design considerations of nanovectors based on magnetic and metallic nanoparticles with surface modifications to reduce toxicity and enable targeted delivery as multimodal imaging agents are also emphasized. [ABSTRACT FROM AUTHOR]