Functionalized nanomaterials: their use as contrast agents in bioimaging: mono- and multimodal approaches

Abstract

The successful development of nanomaterials illustrates the considerable interest in the development of new molecular probes for medical diagnosis and imaging. Substantial progress was made in synthesis protocol and characterization of these materials whereas toxicological issues are sometimes incomplete. Nanoparticle-based contrast agents tend to become efficient tools for enhancing medical diagnostics and surgery for a wide range of 2 imaging modalities. Multimodal nanoparticles (NPs) are much more efficient than conventional molecular-scale contrast agents. They provide new abilities for in vivo detection and enhanced targeting efficiencies through longer circulation times, designed clearance pathways, and multiple binding capacities. Properly protected, they can safely be used for the fabrication of various functional systems with targeting properties, reduced toxicity and proper removal from the body. This review mainly describes the advances in the development of mono-to multimodal NPs and their in vitro and in vivo relevant biomedical applications ranging from imaging and tracking to cancer treatment. Besides specific applications for classical imaging, (MRI, PET, CT, US, PAI) are also mentioned less common imaging techniques such as terahertz molecular imaging (THMI) or ion beam analysis (IBA).Perspectives on multimodal theranostic NPs and their potential for clinical advances are also mentioned.

Radiolabeled Nanoparticles for In Vivo Tumor PET Imaging

“…They are usually coated with dextran or polyethylene glycol (PEG), [16][17][18][19][20] and can mainly be divided into magnetic (μm), superparamagnetic (several hundred nm) and ultrasmall paramagnetic (<50 nm) iron oxide based on size. 21 IO-NPs are an important category in the field of biomaterials and biomedicine, especially used as contrast agents in MRI.…”

Silver and Gadolinium Ions Co-substituted Hydroxyapatite Nanoparticles as Bimodal Contrast Agent for Medical Imaging

“…MRI is a non-ionizing imaging method that offers a high soft tissue contrast and provides high spatial resolution. This technique is based on measuring water proton relaxation states under a magnetic field [5,13]. Gadolinium (III) or Gd 3+ ion is a commonly used positive contrast for MRI by enhancing the T1 relaxation in T1 weighed images.…”

“…Gd 3+ ion has been incorporated into silica, carbon nanotubes etc., to provide brighter MR signal [14,15]. CT is the most powerful imaging technique employing X-ray ionization and found to be very ideal for hard tissue imaging [5]. Iodinated nanoparticles, gold nanoparticles, iron oxide nanoparticles etc., are popular nanoparticulate contrast agents studied for CT/X-ray imaging [5].…”

“…Studies are being carried out to combine different modes of imaging by developing a single contrast agent based on polymers, liposomes and inorganic nanoparticles like hydroxyapatite (HA) [3,4]. Some of the ideal properties required for a contrast agent include colloidal stability independent of pH and temperature variations, high selectivity and sensitivity, sufficient blood circulation time and easy renal clearance [5,6]. Multimodal contrast agents based on inorganic nanoparticles have attracted considerable attention due to their small tunable size and attractive physical and chemical properties including bio-functionalization, prolonged circulating half-life, passive accumulation at tumor site through enhanced permeation and retention (EPR) effect [5].…”

“…Some of the ideal properties required for a contrast agent include colloidal stability independent of pH and temperature variations, high selectivity and sensitivity, sufficient blood circulation time and easy renal clearance [5,6]. Multimodal contrast agents based on inorganic nanoparticles have attracted considerable attention due to their small tunable size and attractive physical and chemical properties including bio-functionalization, prolonged circulating half-life, passive accumulation at tumor site through enhanced permeation and retention (EPR) effect [5]. The nanoparticulate contrast agents have been reported to provide enhanced signal sensitivity and impart information at the cellular levels [7].…”