Bimodal Nd-Doped LuVO4 Nanoprobes Functionalized with Polyacrilic Acid for X-Ray Computed Tomography and NIR Luminescent Imaging

NIR-I Dye-Based Probe: A New Window for Bimodal Tumor Theranostics

Near-infrared (NIR, 650–1700 nm) bioimaging has emerged as a powerful strategy in tumor diagnosis. In particular, NIR-I fluorescence imaging (650–950 nm) has drawn more attention, benefiting from the high quantum yield and good biocompatibility. Since their biomedical applications are slightly limited by their relatively low penetration depth, NIR-I fluorescence imaging probes have been under extensive development in recent years. This review summarizes the particular application of the NIR-I fluorescent dye-contained bimodal probes, with emphasis on related nanoprobes. These probes have enabled us to overcome the drawbacks of individual imaging modalities as well as achieve synergistic imaging. Meanwhile, the application of these NIR-I fluorescence-based bimodal probes for cancer theranostics is highlighted.

Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

Investigation of Polyacrylic Acid Toxicity in Human Breast Cancer (MCF-7) and Mouse Fibroblast (L-929) Cell Lines

In recent years, biopolymers have been widely used in various fields of medicine. Before using any polymer, its biocompatibility should be examined. Polyacrylic acid (PAA), a polyelectrolyte, is known to be used as an adjuvant effect in immunology, anti-thrombogenic effect in medical experiments, and as a carrier in drug delivery systems. Although there are studies on various conjugates and nanoparticles of PAA, studies on its toxicity alone are limited. Determination of toxicity in biopolymer studies is extremely important. Cultures of various cells are used for toxicity analyses. This study aimed to investigate the toxicity of PAA in human breast cancer (MCF-7) and mouse fibroblast (L-929) cell lines by various methods. Cell culture, 3-(4,5-dimethyltriazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), trypan blue and 4,6-diamidino 2 phenylindole (DAPI) methods were used in the study. The half-maximal effective concentration (EC50) value of PAA was 6.6 mg/ml in MCF 7 cells and 1.8 mg/ ml in L-929 cells. Apoptosis was observed in cells on the increasing PAA concentration with DAPI. With these results, the cytotoxic properties of PAA were determined in vitro. Accordingly, the biocompatibility of polymers to be used in modeling should be supported by in vitro and in vivo studies.

Three-term conjugate gradient method for X-ray luminescence computed tomography

X-ray luminescence computed tomography (XLCT) has become an emerging hybrid molecular imaging technology with high detection sensitivity and low cost. However, the inverse problem of reconstruction has severe ill-posed consequences. The original regularization algorithm needs to take much time to solve the problem. To reduce the cost of time, a three-term conjugate gradient (TTCG) algorithm is proposed for XLCT. Useful truncation information is added to the descent direction to find the optimal solution quickly in our proposed algorithm. Both numerical simulation experiments and real experiments are carried out to verify the performance of the algorithm. Experimental results show that the presented algorithm can effectively speed up the reconstruction process.

Ultra-small gold nanoparticles self-assembled by gadolinium ions for enhanced photothermal/photodynamic liver cancer therapy

Gold nanomaterials are widely used in biomedical research as drug delivery systems, imaging agents and therapeutic materials owing to their unique physicochemical properties and high biocompatibility. In this study, we prepared ultra-small gold nanoparticles (AuNPs) and induced them with gadolinium ions to form a spherical self-assembly. The nanoparticles were coupled with matrix metalloproteinase-2 (MMP-2) and loaded with the photosensitive drug IR820 for photothermal/photodynamic combination therapy of liver cancer. The formed nanoprobes were metabolised in vivo via degradation under dual-mode real-time imaging because of their acid response degradation characteristics. In addition, the nanoprobe showed excellent tumour-targeting ability due to the presence of surface-modified MMP-2. In vivo treatment experiments revealed that the nanoprobes achieved enhanced photodynamic/photothermal combination therapy under laser irradiation and significantly inhibited tumour growth. Therefore, the nanoprobes have great potential for anti-tumour therapy guided by dual-mode real-time imaging of liver cancer.

Dysprosium and Holmium Vanadate Nanoprobes as High-Performance Contrast Agents for High-Field Magnetic Resonance and Computed Tomography Imaging

We describe a wet chemical method for the synthesis of uniform and well-dispersed dysprosium vanadate (DyVO₄) and holmium vanadate (HoVO₄) nanoparticles with an almost spherical shape and a mean size of ∼60 nm and their functionalization with poly(acrylic acid). The transverse magnetic relaxivity of both systems at 9.4 T is analyzed on the basis of magnetic susceptibility and magnetization measurements in order to evaluate their potential for application as high-field MRI contrast agents. In addition, the X-ray attenuation properties of these systems are also studied to determine their capabilities as computed tomography contrast agent. Finally, the colloidal stability under physiological pH conditions and the cytotoxicity of the functionalized NPs are also addressed to assess their suitability for bioimaging applications.