Submit to Nanomaterials Review for Nanomaterials Propose a Special Issue

Journal Browser

► Journal Browser

Nanomaterials for Contrast Agent and Biomedical Imaging

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Biology and Medicines".

Deadline for manuscript submissions: closed (27 May 2021) | Viewed by 43463

Share This Special Issue

Special Issue Editor

Dr. Pasquina Marzola

E-Mail Website
Guest Editor

Department of Computer Science, School of Science and Engineering, University of Verona, Verona, Italy
Interests: magnetic resonance imaging, nanotechnology in diagnosis and therapy, contrast agents, cellular and molecular imaging

Special Issue Information

Dear colleagues,

A key focus of nanotechnology for biomedical application is the use of nanomaterials as Contrast Agents (CA) for anatomical and functional imaging. Nanosized CA have been developed for virtually any of the Biomedical Imaging modalities nowadays available in both clinical and preclinical fields. By exploiting the potential of nanotechnology, researchers have designed nanomaterials containing probes for different imaging modalities (multimodal CA) and targeting moieties, such as peptides or antibodies, which in principle could improve the specificity of the CA.

Due to the presence of large fenestrations in the endothelium of tumour blood vessels, nanomaterials may extravasate more easily in cancerous than in healthy tissues with a consequent accumulation of the CA in the tumour. For the above reason, nanomaterials are excellent candidates for tumour diagnosis, although massive capture in the reticuloendothelial system strongly limits the percentage of the injected dose that actually reaches tumour tissue.

Despite a limited cost/benefit ratio and some safety concerns which have prevented until now the clinical development and widespread use of nanomaterials as CA and biomedical imaging tools, this is a flourishing and original research field. The aim of this special number of “Nanomaterials” is to provide an overview of the most recent and promising developments in this topic.

Dr. Pasquina Marzola
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Nanoparticles
Nanomaterials
Contrast Agents
Multimodal Imaging

Published Papers (14 papers)

Download All Papers

Research

Jump to: Review

12 pages, 1947 KiB

Open AccessArticle

Gold-Conjugated Nanobodies for Targeted Imaging Using High-Resolution Secondary Ion Mass Spectrometry

by Paola Agüi-Gonzalez, Tal M. Dankovich, Silvio O. Rizzoli and Nhu T. N. Phan

Nanomaterials 2021, 11(7), 1797; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11071797 - 10 Jul 2021

Cited by 6 | Viewed by 3052

Abstract

Nanoscale imaging with the ability to identify cellular organelles and protein complexes has been a highly challenging subject in the secondary ion mass spectrometry (SIMS) of biological samples. This is because only a few isotopic tags can be used successfully to target specific proteins or organelles. To address this, we generated gold nanoprobes, in which gold nanoparticles are conjugated to nanobodies. The nanoprobes were well suited for specific molecular imaging using NanoSIMS at subcellular resolution. They were demonstrated to be highly selective to different proteins of interest and sufficiently sensitive for SIMS detection. The nanoprobes offer the possibility of correlating the investigation of cellular isotopic turnover to the positions of specific proteins and organelles, thereby enabling an understanding of functional and structural relations that are currently obscure. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

11 pages, 679 KiB

Open AccessArticle

Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with ^99mTc and ⁶⁸Ga

by Manuela Marenco, Letizia Canziani, Gianluca De Matteis, Giorgio Cavenaghi, Carlo Aprile and Lorenzo Lodola

Nanomaterials 2021, 11(7), 1776; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11071776 - 08 Jul 2021

Cited by 7 | Viewed by 2117

Abstract

Nanoparticles of Human Serum Albumin (NC) labelled with ^99mTc are widely used in Nuclear Medicine and represent the gold-standard for the intraoperative detection of the sentinel lymph node in many kinds of cancer, mainly breast cancer and melanoma. A significant amount of radionuclides can be incorporated into the HSA particle, due to the multiple binding sites, and HSA-based nanocolloid catabolism is a fast and easy process that results in innocuous degradation products. NCs labelled with different isotopes represent an interesting radiopharmaceutical for extending diagnostic accuracy and surgical outcome, but the knowledge of the chemical bond between NCs and isotopes has not been fully elucidated, including information on its strength and specificity. The aim of this study is to investigate and compare the physicochemical characteristics of the bond between NCs and ^99mTc and ⁶⁸Ga isotopes. Commercial kits of HSA-based nanocolloid particles (NanoAlbumon^®) were used. For this purpose, we have primarily studied the kinetic orders of NC radiolabelling. Langmuir isotherms and pH effect on radiolabelling were tested and the stability of the radiometal complex was verified through competition reactions carried out in presence of different ligands. The future goal of our research is the development of inexpensive and instant kits, easily labelled with a wide spectrum of diagnostic and therapeutic isotopes, thus facilitating the availability of versatile and multipurpose radiopharmaceuticals. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

10 pages, 19189 KiB

Open AccessArticle

Dark Field and Coherent Anti-Stokes Raman (DF-CARS) Imaging of Cell Uptake of Core-Shell, Magnetic-Plasmonic Nanoparticles

by Grace Brennan, Sally Ryan, Tewfik Soulimane, Syed A. M. Tofail and Christophe Silien

Nanomaterials 2021, 11(3), 685; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11030685 - 09 Mar 2021

Cited by 1 | Viewed by 1993

Abstract

Magnetic-plasmonic, Fe₃O₄-Au, core-shell nanoparticles are popular in many applications, most notably in therapeutics and diagnostics, and thus, the imaging of these nanostructures in biological samples is of high importance. These nanostructures are typically imaged in biological material by dark field scatter imaging, which requires an even distribution of nanostructures in the sample and, therefore, high nanoparticle doses, potentially leading to toxicology issues. Herein, we explore the nonlinear optical properties of magnetic nanoparticles coated with various thicknesses of gold using the open aperture z-scan technique to determine the nonlinear optical properties and moreover, predict the efficacy of the nanostructures in nonlinear imaging. We find that the magnetic nanoparticles coated with gold nanoseeds and thinner gold shells (ca. 4 nm) show the largest nonlinear absorption coefficient β and imaginary part of the third-order susceptibility Im χ⁽³⁾, suggesting that these nanostructures would be suitable contrast agents. Next, we combine laser dark field microscopy and epi-detected coherent anti-Stokes Raman (CARS) microscopy to image the uptake of magnetic-plasmonic nanoparticles in human pancreatic cancer cells. We show the epi-detected CARS technique is suitable for imaging of the magnetic-plasmonic nanoparticles without requiring a dense distribution of nanoparticles. This technique achieves superior nanoparticle contrasting over both epi-detected backscatter imaging and transmission dark field imaging, while also attaining label-free chemical contrasting of the cell. Lastly, we show the high biocompatibility of the Fe₃O₄ nanoparticles with ca. 4-nm thick Au shell at concentrations of 10–100 µg/mL. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

21 pages, 4709 KiB

Open AccessArticle

Colloidally Stable P(DMA-AGME)-Ale-Coated Gd(Tb)F₃:Tb³⁺(Gd³⁺),Yb³⁺,Nd³⁺ Nanoparticles as a Multimodal Contrast Agent for Down- and Upconversion Luminescence, Magnetic Resonance Imaging, and Computed Tomography

by Oleksandr Shapoval, Viktoriia Oleksa, Miroslav Šlouf, Volodymyr Lobaz, Olga Trhlíková, Marcela Filipová, Olga Janoušková, Hana Engstová, Jan Pankrác, Adam Modrý, Vít Herynek, Petr Ježek, Luděk Šefc and Daniel Horák

Nanomaterials 2021, 11(1), 230; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11010230 - 16 Jan 2021

Cited by 13 | Viewed by 3192

Abstract

Multimodal imaging, integrating several modalities including down- and up-conversion luminescence, T₁- and T₂(T₂*)-weighted MRI, and CT contrasting in one system, is very promising for improved diagnosis of severe medical disorders. To reach the goal, it is necessary to develop suitable nanoparticles that are highly colloidally stable in biologically relevant media. Here, hydrophilic poly(N,N-dimethylacrylamide-N-acryloylglycine methyl ester)-alendronate-[P(DMA-AGME)-Ale]-coated Gd(Tb)F₃:Tb³⁺(Gd³⁺),Yb³⁺,Nd³⁺ nanoparticles were synthesized by a coprecipitation method in ethylene glycol (EG) followed by coating with the polymer. The particles were tho-roughly characterized by a dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray energy dispersive spectroscopy (EDAX), selected area electron diffraction (SAED), elemental ana-lysis and fluorescence spectroscopy. Aqueous particle dispersions exhibited excellent colloidal stability in water and physiological buffers. In vitro toxicity assessments suggested no or only mild toxicity of the surface-engineered Gd(Tb)F₃:Tb³⁺(Gd³⁺),Yb³⁺,Nd³⁺ particles in a wide range of concentrations. Internalization of the particles by several types of cells, including HeLa, HF, HepG2, and INS, was confirmed by a down- and up-conversion confocal microscopy. Newly developed particles thus proved to be an efficient contrast agent for fluorescence imaging, T₁- and T₂(T₂*)-weighted magnetic resonance imaging (MRI), and computed tomography (CT). Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

12 pages, 4011 KiB

Open AccessArticle

Apoferritin Amyloid-Fibril Directed the In Situ Assembly and/or Synthesis of Optical and Magnetic Nanoparticles

by Rocío Jurado and Natividad Gálvez

Nanomaterials 2021, 11(1), 146; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11010146 - 08 Jan 2021

Cited by 8 | Viewed by 2137

Abstract

The coupling of proteins that can assemble, recognise or mineralise specific inorganic species is a promising strategy for the synthesis of nanoscale materials with a controllable morphology and functionality. Herein, we report that apoferritin protein amyloid fibrils (APO) have the ability to assemble and/or synthesise various metal and metal compound nanoparticles (NPs). As such, we prepared metal NP–protein hybrid bioconjugates with improved optical and magnetic properties by coupling diverse gold (AuNPs) and magnetic iron oxide nanoparticles (MNPs) to apoferritin amyloid fibrils and compared them to the well-known β-lactoglobulin (BLG) protein. In a second approach, we used of solvent-exposed metal-binding residues in APO amyloid fibrils as nanoreactors for the in situ synthesis of gold, silver (AgNPs) and palladium nanoparticles (PdNPs). Our results demonstrate, the versatile nature of the APO biotemplate and its high potential for preparing functional hybrid bionanomaterials. Specifically, the use of apoferritin fibrils as vectors to integrate magnetic MNPs or AuNPs is a promising synthetic strategy for the preparation of specific contrast agents for early in vivo detection using various bioimaging techniques. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

29 pages, 26171 KiB

Open AccessArticle

α_vβ₃-Specific Gold Nanoparticles for Fluorescence Imaging of Tumor Angiogenesis

by Marc Pretze, Valeska von Kiedrowski, Roswitha Runge, Robert Freudenberg, René Hübner, Güllü Davarci, Ralf Schirrmacher, Carmen Wängler and Björn Wängler

Nanomaterials 2021, 11(1), 138; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11010138 - 08 Jan 2021

Cited by 7 | Viewed by 2649

Abstract

This paper reports on the development of tumor-specific gold nanoparticles (AuNPs) as theranostic tools intended for target accumulation and the detection of tumor angiogenesis via optical imaging (OI) before therapy is performed, being initiated via an external X-ray irradiation source. The AuNPs were decorated with a near-infrared dye, and RGD peptides as the tumor targeting vector for α_vβ₃-integrin, which is overexpressed in tissue with high tumor angiogenesis. The AuNPs were evaluated in an optical imaging setting in vitro and in vivo exhibiting favorable diagnostic properties with regards to tumor cell accumulation, biodistribution, and clearance. Furthermore, the therapeutic properties of the AuNPs were evaluated in vitro on pUC19 DNA and on A431 cells concerning acute and long-term toxicity, indicating that these AuNPs could be useful as radiosensitizers in therapeutic concepts in the future. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

13 pages, 2658 KiB

Open AccessArticle

Imaging and Characterization of Sustained Gadolinium Nanoparticle Release from Next Generation Radiotherapy Biomaterial

by Romy Mueller, Michele Moreau, Sayeda Yasmin-Karim, Andrea Protti, Olivier Tillement, Ross Berbeco, Jürgen Hesser and Wilfred Ngwa

Nanomaterials 2020, 10(11), 2249; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10112249 - 13 Nov 2020

Cited by 12 | Viewed by 2575

Abstract

Smart radiotherapy biomaterials (SRBs) present a new opportunity to enhance image-guided radiotherapy while replacing routinely used inert radiotherapy biomaterials like fiducials. In this study the potential of SRBs loaded with gadolinium-based nanoparticles (GdNPs) is investigated for magnetic resonance imaging (MRI) contrast. GdNP release from SRB is quantified and modelled for accurate prediction. SRBs were manufactured similar to fiducials, with a cylindrical shell consisting of poly(lactic-co-glycolic) acid (PLGA) and a core loaded with GdNPs. Magnetic resonance imaging (MRI) contrast was investigated at 7T in vitro (in agar) and in vivo in subcutaneous tumors grown with the LLC1 lung cancer cell line in C57/BL6 mice. GdNPs were quantified in-phantom and in tumor and their release was modelled by the Weibull distribution. Gd concentration was linearly fitted to the R₁ relaxation rate with a detection limit of 0.004 mmol/L and high confidence level (R² = 0.9843). GdNP loaded SRBs in tumor were clearly visible up to at least 14 days post-implantation. Signal decrease during this time showed GdNP release in vivo, which was calculated as 3.86 ± 0.34 µg GdNPs release into the tumor. This study demonstrates potential and feasibility for SRBs with MRI-contrast, and sensitive GdNP quantification and release from SRBs in a preclinical animal model. The feasibility of monitoring nanoparticle (NP) concentration during treatment, allowing dynamic quantitative treatment planning, is also discussed. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

15 pages, 8468 KiB

Open AccessArticle

Fluorescent, Prussian Blue-Based Biocompatible Nanoparticle System for Multimodal Imaging Contrast

by László Forgách, Nikolett Hegedűs, Ildikó Horváth, Bálint Kiss, Noémi Kovács, Zoltán Varga, Géza Jakab, Tibor Kovács, Parasuraman Padmanabhan, Krisztián Szigeti and Domokos Máthé

Nanomaterials 2020, 10(9), 1732; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10091732 - 31 Aug 2020

Cited by 6 | Viewed by 3899

Abstract

(1) Background. The main goal of this work was to develop a fluorescent dye-labelling technique for our previously described nanosized platform, citrate-coated Prussian blue (PB) nanoparticles (PBNPs). In addition, characteristics and stability of the PB nanoparticles labelled with fluorescent dyes were determined. (2) Methods. We adsorbed the fluorescent dyes Eosin Y and Rhodamine B and methylene blue (MB) to PB-nanoparticle systems. The physicochemical properties of these fluorescent dye-labeled PBNPs (iron(II);iron(III);octadecacyanide) were determined using atomic force microscopy, dynamic light scattering, zeta potential measurements, scanning- and transmission electron microscopy, X-ray diffraction, and Fourier-transformation infrared spectroscopy. A methylene-blue (MB) labelled, polyethylene-glycol stabilized PBNP platform was selected for further assessment of in vivo distribution and fluorescent imaging after intravenous administration in mice. (3) Results. The MB-labelled particles emitted a strong fluorescent signal at 662 nm. We found that the fluorescent light emission and steric stabilization made this PBNP-MB particle platform applicable for in vivo optical imaging. (4) Conclusion. We successfully produced a fluorescent and stable, Prussian blue-based nanosystem. The particles can be used as a platform for imaging contrast enhancement. In vivo stability and biodistribution studies revealed new aspects of the use of PBNPs. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

18 pages, 2184 KiB

Open AccessArticle

Magneto-Liposomes as MRI Contrast Agents: A Systematic Study of Different Liposomal Formulations

by Nina Kostevšek, Calvin C. L. Cheung, Igor Serša, Mateja Erdani Kreft, Ilaria Monaco, Mauro Comes Franchini, Janja Vidmar and Wafa T. Al-Jamal

Nanomaterials 2020, 10(5), 889; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10050889 - 06 May 2020

Cited by 27 | Viewed by 3649

Abstract

The majority of the clinically approved iron oxide nanoparticles (IO NPs) used as contrast agents for magnetic resonance imaging (MRI) have been withdrawn from the market either due to safety concerns or lack of profits. To address this challenge, liposomes have been used to prepare IO-based T₂ contrast agents. We studied the influence of different phospholipids on the relaxivity (r₂) values of magneto-liposomes (MLs) containing magnetic NPs in the bilayer, where a strong correlation between the bilayer fluidity and r₂ is clearly shown. Embedding 5-nm IO NPs in the lipid bilayer leads to a significant improvement in their relaxivity, where r₂ values range from 153 ± 5 s⁻¹ mM⁻¹ for DPPC/cholesterol/DSPE-PEG (96/50/4) up to 673 ± 12 s⁻¹ mM⁻¹ for DOPC/DSPE-PEG (96/4), compared to “free” IO NPs with an r₂ value of 16 s⁻¹ mM⁻¹, measured at 9.4 T MRI scanner. In vitro MRI measurements, together with the ICP-MS analysis, revealed MLs as highly selective contrast agents that were preferentially taken up by cancerous T24 cells, which led to an improvement in the contrast and an easier distinction between the healthy and the cancerous cells. A careful selection of the lipid bilayer to prepare MLs could offer efficient MRI contrast agents, even at very low IO NP concentrations. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

11 pages, 5094 KiB

Open AccessArticle

Porous Si Microparticles Infiltrated with Magnetic Nanospheres

by Elena Chistè, Gloria Ischia, Marco Gerosa, Pasquina Marzola, Marina Scarpa and Nicola Daldosso

Nanomaterials 2020, 10(3), 463; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10030463 - 04 Mar 2020

Viewed by 2495

Abstract

Porous silicon (pSi) microparticles obtained by porosification of crystalline silicon wafers have unique optical properties that, together with biodegradability, biocompatibility and absence of immunogenicity, are fundamental characteristics to candidate them as tracers in optical imaging techniques and as drug carriers. In this work, we focus on the possibility to track down the pSi microparticles also by MRI (magnetic resonance imaging), thus realizing a comprehensive tool for theranostic applications, i.e., the combination of therapy and diagnostics. We have developed and tested an easy, quick and low-cost protocol to infiltrate the COOH-functionalized pSi microparticles pores (tens of nanometers about) with magnetic nanospheres (SPIONs—Super Paramagnetic Iron Oxide Nanoparticles, about 5–7 nm) and allow an electrostatic interaction. The structural properties and the elemental composition were investigated by electron microscopy techniques coupled to elemental analysis to demonstrate the effective attachment of the SPIONs along the pores’ surface of the pSi microparticles. The magnetic properties were investigated under an external magnetic field to determine the relaxivity properties of the material and resulting in an alteration of the relaxivity of water due to the SPIONs presence, clearly demonstrating the effectiveness of the easy functionalization protocol proposed. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

17 pages, 4892 KiB

Open AccessArticle

MPI Phantom Study with A High-Performing Multicore Tracer Made by Coprecipitation

by Harald Kratz, Azadeh Mohtashamdolatshahi, Dietmar Eberbeck, Olaf Kosch, Ralf Hauptmann, Frank Wiekhorst, Matthias Taupitz, Bernd Hamm and Jörg Schnorr

Nanomaterials 2019, 9(10), 1466; https://0-doi-org.brum.beds.ac.uk/10.3390/nano9101466 - 16 Oct 2019

Cited by 18 | Viewed by 3441

Abstract

Magnetic particle imaging (MPI) is a new imaging technique that detects the spatial distribution of magnetic nanoparticles (MNP) with the option of high temporal resolution. MPI relies on particular MNP as tracers with tailored characteristics for improvement of sensitivity and image resolution. For this reason, we developed optimized multicore particles (MCP 3) made by coprecipitation via synthesis of green rust and subsequent oxidation to iron oxide cores consisting of a magnetite/maghemite mixed phase. MCP 3 shows high saturation magnetization close to that of bulk maghemite and provides excellent magnetic particle spectroscopy properties which are superior to Resovist^® and any other up to now published MPI tracers made by coprecipitation. To evaluate the MPI characteristics of MCP 3 two kinds of tube phantoms were prepared and investigated to assess sensitivity, spatial resolution, artifact severity, and selectivity. Resovist^® was used as standard of comparison. For image reconstruction, the regularization factor was optimized, and the resulting images were investigated in terms of quantifying of volumes and iron content. Our results demonstrate the superiority of MCP 3 over Resovist^® for all investigated MPI characteristics and suggest that MCP 3 is promising for future experimental in vivo studies. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

Review

Jump to: Research

16 pages, 2877 KiB

Open AccessReview

Iron Oxide Nanoparticles as Theranostic Agents in Cancer Immunotherapy

by Rossella Canese, Federica Vurro and Pasquina Marzola

Nanomaterials 2021, 11(8), 1950; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11081950 - 29 Jul 2021

Cited by 16 | Viewed by 3409

Abstract

Starting from the mid-1990s, several iron oxide nanoparticles (NPs) were developed as MRI contrast agents. Since their sizes fall in the tenths of a nanometer range, after i.v. injection these NPs are preferentially captured by the reticuloendothelial system of the liver. They have therefore been proposed as liver-specific contrast agents. Even though their unfavorable cost/benefit ratio has led to their withdrawal from the market, innovative applications have recently prompted a renewal of interest in these NPs. One important and innovative application is as diagnostic agents in cancer immunotherapy, thanks to their ability to track tumor-associated macrophages (TAMs) in vivo. It is worth noting that iron oxide NPs may also have a therapeutic role, given their ability to alter macrophage polarization. This review is devoted to the most recent advances in applications of iron oxide NPs in tumor diagnosis and therapy. The intrinsic therapeutic effect of these NPs on tumor growth, their capability to alter macrophage polarization and their diagnostic potential are examined. Innovative strategies for NP-based drug delivery in tumors (e.g., magnetic resonance targeting) will also be described. Finally, the review looks at their role as tracers for innovative, and very promising, imaging techniques (magnetic particle imaging-MPI). Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Figure 1

30 pages, 5979 KiB

Open AccessReview

Photostability of Contrast Agents for Photoacoustics: The Case of Gold Nanorods

by Lucia Cavigli, Boris N. Khlebtsov, Sonia Centi, Nikolai G. Khlebtsov, Roberto Pini and Fulvio Ratto

Nanomaterials 2021, 11(1), 116; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11010116 - 06 Jan 2021

Cited by 19 | Viewed by 3726

Abstract

Plasmonic particles as gold nanorods have emerged as powerful contrast agents for critical applications as the photoacoustic imaging and photothermal ablation of cancer. However, their unique efficiency of photothermal conversion may turn into a practical disadvantage, and expose them to the risk of overheating and irreversible photodamage. Here, we outline the main ideas behind the technology of photoacoustic imaging and the use of relevant contrast agents, with a main focus on gold nanorods. We delve into the processes of premelting and reshaping of gold nanorods under illumination with optical pulses of a typical duration in the order of few ns, and we present different approaches to mitigate this issue. We undertake a retrospective classification of such approaches according to their underlying, often implicit, principles as: constraining the initial shape; or speeding up their thermal coupling to the environment by lowering their interfacial thermal resistance; or redistributing the input energy among more particles. We discuss advantages, disadvantages and contexts of practical interest where one solution may be more appropriate than the other. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures

Graphical abstract

24 pages, 2205 KiB

Open AccessReview

Nanoparticles for Cerenkov and Radioluminescent Light Enhancement for Imaging and Radiotherapy

by Federico Boschi and Antonello Enrico Spinelli

Nanomaterials 2020, 10(9), 1771; https://0-doi-org.brum.beds.ac.uk/10.3390/nano10091771 - 07 Sep 2020

Cited by 12 | Viewed by 3690

Abstract

Cerenkov luminescence imaging and Cerenkov photodynamic therapy have been developed in recent years to exploit the Cerenkov radiation (CR) generated by radioisotopes, frequently used in Nuclear Medicine, to diagnose and fight cancer lesions. For in vivo detection, the endpoint energy of the radioisotope and, thus, the total number of the emitted Cerenkov photons, represents a very important variable and explains why, for example, ⁶⁸Ga is better than ¹⁸F. However, it was also found that the scintillation process is an important mechanism for light production. Nanotechnology represents the most important field, providing nanosctructures which are able to shift the UV-blue emission into a more suitable wavelength, with reduced absorption, which is useful especially for in vivo imaging and therapy applications. Nanoparticles can be made, loaded or linked to fluorescent dyes to modify the optical properties of CR radiation. They also represent a useful platform for therapeutic agents, such as photosensitizer drugs for the production of reactive oxygen species (ROS). Generally, NPs can be spaced by CR sources; however, for in vivo imaging applications, NPs bound to or incorporating radioisotopes are the most interesting nanocomplexes thanks to their high degree of mutual colocalization and the reduced problem of false uptake detection. Moreover, the distance between the NPs and CR source is crucial for energy conversion. Here, we review the principal NPs proposed in the literature, discussing their properties and the main results obtained by the proponent experimental groups. Full article

(This article belongs to the Special Issue Nanomaterials for Contrast Agent and Biomedical Imaging)

► Show Figures