Improving the MR Imaging Sensitivity of Upconversion Nanoparticles by an Internal and External Incorporation of the Gd(3+) Strategy for in Vivo Tumor-Targeted Imaging

Trend of albumin nanoparticles in oncology: a bibliometric analysis of research progress and prospects

Background

Delivery systems based on albumin nanoparticles (NPs) have recently garnered substantial interest in anti-tumor drug development. However, systematic bibliometric analyses in this field remain lacking. This study aimed to analyze the current research status, hotspots, and frontiers in the application of albumin NPs in the field of oncology from a bibliometric perspective.

Methods

Using the Web of Science Core Collection (WOSCC) as the data source, retrieved articles were analyzed using software, such as VOSviewer 1.6.18 and CiteSpace 6.1.6, and the relevant visualization maps were plotted.

Results

From 1 January 2000, to 15 April 2024, 2,262 institutions from 67 countries/regions published 1,624 articles related to the application of albumin NPs in the field of oncology. The USA was a leader in this field and held a formidable academic reputation. The most productive institution was the Chinese Academy of Sciences. The most productive author was Youn YS, whereas Kratz F was the most frequently co-cited author. The most productive journal was the International Journal of Nanomedicine, whereas the Journal of Controlled Release was the most co-cited journal. Future research hotspots and frontiers included "rapid and convenient synthesis methods predominated by self-assembly," "surface modification," "construction of multifunctional NPs for theranostics," "research on natural active ingredients mainly based on phenolic compounds," "combination therapy," and "clinical applications."

Conclusion

Based on our bibliometric analysis and summary, we obtained an overview of the research on albumin NPs in the field of oncology, identified the most influential countries, institutions, authors, journals, and citations, and discussed the current research hotspots and frontiers in this field. Our study may serve as an important reference for future research in this field.

Construction of a Functional Nucleic Acid-Based Artificial Vesicle-Encapsulated Composite Nanoparticle and Its Application in Retinoblastoma-Targeted Theranostics

Retinoblastoma (RB) is an aggressive tumor of the infant retina. However, the ineffective targeting of its theranostic agents results in poor imaging and therapeutic efficacy, which makes it difficult to identify and treat RB at an early stage. In order to improve the imaging and therapeutic efficacy, we constructed an RB-targeted artificial vesicle composite nanoparticle. In this study, the MnO2 nanosponge (hMNs) was used as the core to absorb two fluorophore-modified DNAzymes to form the Dual/hMNs nanoparticle; after loaded with the artificial vesicle derived from human red blood cells, the RB-targeted DNA aptamers were modified on the surface, thus forming the Apt-EG@Dual/hMNs complex nanoparticle. The DNA aptamer endows this nanoparticle to target the nucleolin-overexpressed RB cell membrane specifically and enters cells via endocytosis. The nanoparticle could release fluorophore-modified DNAzymes and supplies Mn2+ as a DNAzyme cofactor and a magnetic resonance imaging (MRI) agent. Subsequently, the DNAzymes can target two different mRNAs, thereby realizing fluorescence/MR bimodal imaging and dual-gene therapy. This study is expected to provide a reliable and valuable basis for ocular tumor theranostics.

Polyethyleneimine-Based Drug Delivery Systems for Cancer Theranostics

With the development of nanotechnology, various types of polymer-based drug delivery systems have been designed for biomedical applications. Polymer-based drug delivery systems with desirable biocompatibility can be efficiently delivered to tumor sites with passive or targeted effects and combined with other therapeutic and imaging agents for cancer theranostics. As an effective vehicle for drug and gene delivery, polyethyleneimine (PEI) has been extensively studied due to its rich surface amines and excellent water solubility. In this work, we summarize the surface modifications of PEI to enhance biocompatibility and functionalization. Additionally, the synthesis of PEI-based nanoparticles is discussed. We further review the applications of PEI-based drug delivery systems in cancer treatment, cancer imaging, and cancer theranostics. Finally, we thoroughly consider the outlook and challenges relating to PEI-based drug delivery systems.

Bioimaging with Upconversion Nanoparticles

Bioimaging enables the spatiotemporal visualization of biological processes at various scales empowered by a range of different imaging modalities and contrast agents. Upconversion nanoparticles (UCNPs) represent a distinct type of such contrast agents with the potential to transform bioimaging due to their unique optical properties and functional design flexibilities. This review explores and discusses the opportunities, challenges, and limitations that UCNPs exhibit as bioimaging probes and highlights applications with spatial dimensions ranging from the single nanoparticle level to cellular, tissue, and whole animal imaging. We further summarized recent advancements in bioimaging applications enabled by UCNPs, including super-resolution techniques and multimodal imaging methods, and provide a perspective on the future potential of UCNP-based technologies in bioimaging research and clinical translation. This review may provide a valuable resource for researchers interested in exploring and applying UCNP-based bioimaging technologies.

Integration of Au Nanosheets and GdOF:Yb,Er for NIR-I and NIR-II Light-Activated Synergistic Theranostics

The local hyperthermia (>41 °C) effect of photothermal therapy (PTT) is significantly limited by the efficiency of PTT agents to convert laser energy to heat, and such oncotherapy, similar to conventional chemotherapy, invariably encounters the challenge of nonspecific application. Undue reliance on oxygen sources still poses particular difficulties in photodynamic therapy (PDT) for deep-level clinical applications. Considering these therapeutic issues, in this study, we constructed a versatile but unique nanosystem by encapsulating Au nanosheets in codoped gadolinium oxyfluoride (GdOF):Yb,Er spheres, followed by decoration of a chemotherapeutic drug (doxorubicin), photosensitizer (rose Bengal, RB), and targeted agent (folic acid). This allowed the incorporation of cancer treatment and real-time curative efficacy monitoring into one single theranostic nanoplatform. Benefiting from the dual contribution of the strong absorptions in the NIR-I and NIR-II regions, relevant photothermal-conversion efficiency (η) values pertaining to that final product were 39.2% at 1064 nm irradiation and 35.7% at 980 nm illumination. The fluorescence resonance energy transfer that occurred in the up-converted GdOF:Yb,Er to RB contributed to the high PDT efficacy. Combined with a micromeric acid-responsive drug release in a targeted tumor microenvironment, high-performance synergistic therapy was realized. In addition, up-conversion fluorescence imaging and computed tomography imaging accompanied by multimodal magnetic resonance imaging were simultaneously achieved owing to the doped lanthanide ions and the encapsulated Au nanosheets. Our designed oncotherapy nanosystem provides an alternative strategy to acquire ideal theranostic effects.

Insight into the mechanism of intense NIR-to-red upconversion luminescence in Er3+ doped and Er3+–Yb3+ co-doped SrF2 nanoparticles

SrF₂:Yb³⁺,Er³⁺ NPs were synthesized by the hydrothermal method and their luminescence mechanism was discussed in detail, which provided a theoretical basis for further understanding the properties of the materials.

Self-Assembly Fabrication of Honeycomb-like Magnetic-Fluorescent Fe3O4-QDs Nanocomposites for Bimodal Imaging

Magnetic-fluorescent nanocomposites have a tremendous potential in biomedicine realms as a revolutionary dual-modality probe tool for more accurate medical detection. However, complicated and inefficient postprocesses pose obstacles to obtaining high-quality magnetic-fluorescent nanocomposites. Thus, the fabrication of magnetic-fluorescent functional nanocomposites via a simple, effective, and ideal method remains a challenge and is still waiting to be tapped. The new synthesis approaches are becoming impending demands and probably enable us to address these above-mentioned problems. In this contribution, we present a novel self-assembly synthesis route for the construction of magnetic-fluorescent bimodal imaging nanocomposites rather than adopting sophisticated postpreparative processes. The Fe₃O₄ and quatum dots (QDs) nanocomposites were cross-linked fleetly by cerium(III) ion driven coordination bonds in which the cerium(III) ions served as the cross-connecting node and the carboxylate groups acted as bridging ligands. The potential application for dual-modality imaging capability was validated on tumor-bearing mice. This ingenious strategy was extremely efficient and handy for the magnetic-fluorescent Fe₃O₄-QDs nanocomposite construction. Significantly, our cerium(III) ion driven self-assembly method probably has a wide applicability for nanoparticles and organic molecules containing carboxyl groups but extensive explorations are still necessary.

Bioactive Core-Shell CaF2 Upconversion Nanostructure for Promotion and Visualization of Engineered Bone Reconstruction

Inorganic ion metabolism plays significant roles in various life processes including signal transduction, substance exchange, and cellular constructions. Regulation and monitoring of ion metabolism offer great promise to modulate biological activities and provide insights into related mechanisms. Here, a synergistic nanodepot based on a bioactive core-shell CaF₂ upconversion nanostructure that integrates multiple mineral ions for metabolic regulation was built for the acceleration and monitoring of the biomineralization process. Multiple mineral ions released from the nanodepots can accelerate the growth of inorganic crystals and enhance the production of organic matrixes, synergistically facilitating the regeneration of bone defects in vivo. During the process, such a nanodepot can be constructed to specifically recognize osteoblasts for the monitoring of biomineralization. This nanoprobe represents an efficient strategy to promote and monitor biomineralization-related metabolic activities with applications in fundamental research, disease diagnosis, and regenerative medicine.

Recent progress in the development of upconversion nanomaterials in bioimaging and disease treatment

Multifunctional lanthanide-based upconversion nanoparticles (UCNPs), which feature efficiently convert low-energy photons into high-energy photons, have attracted considerable attention in the domain of materials science and biomedical applications. Due to their unique photophysical properties, including light-emitting stability, excellent upconversion luminescence efficiency, low autofluorescence, and high detection sensitivity, and high penetration depth in samples, UCNPs have been widely applied in biomedical applications, such as biosensing, imaging and theranostics. In this review, we briefly introduced the major components of UCNPs and the luminescence mechanism. Then, we compared several common design synthesis strategies and presented their advantages and disadvantages. Several examples of the functionalization of UCNPs were given. Next, we detailed their biological applications in bioimaging and disease treatment, particularly drug delivery and photodynamic therapy, including antibacterial photodynamic therapy. Finally, the future practical applications in materials science and biomedical fields, as well as the remaining challenges to UCNPs application, were described. This review provides useful practical information and insights for the research on and application of UCNPs in the field of cancer.

The Transition from Metal-Based to Metal-Free Contrast Agents for T1 Magnetic Resonance Imaging Enhancement

Magnetic resonance imaging (MRI) has received significant attention as the noninvasive diagnostic technique for complex diseases. Image-guided therapeutic strategy for diseases such as cancer has also been at the front line of biomedical research, thanks to the innovative MRI, enhanced by the prior delivery of contrast agents (CAs) into patients' bodies through injection. These CAs have contributed a great deal to the clinical utility of MRI but have been based on metal-containing compounds such as gadolinium, manganese, and iron oxide. Some of these CAs have led to cytotoxicities such as the incurable Nephrogenic Systemic Fibrosis (NSF), resulting in their removal from the market. On the other hand, CAs based on organic nitroxide radicals, by virtue of their structural composition, are metal free and without the aforementioned drawbacks. They also have improved biocompatibility, ease of functionalization, and long blood circulation times, and have been proven to offer tissue contrast enhancement with longitudinal relaxivities comparable with those for the metal-containing CAs. Thus, this Review highlights the recent progress in metal-based CAs and their shortcomings. In addition, the remarkable goals achieved by the organic nitroxide radical CAs in the enhancement of MR images have also been discussed extensively. The focal point of this Review is to emphasize or demonstrate the crucial need for transition into the use of organic nitroxide radicals-metal-free CAs-as against the metal-containing CAs, with the aim of achieving safer application of MRI for early disease diagnosis and image-guided therapy.

An l-cysteine-mediated iodide-catalyzed reaction for the detection of I−

In this study, a highly selective and eco-friendly fluorescent sensor consisting of upconversion (UCNPs) and gold nanoparticles (AuNPs) was developed for the detection of iodide (I⁻).

Upconversion nanocrystal 'armoured' silica fibres with superior photoluminescence for miRNA detection

We have fabricated a flexible membrane, consisting of SiO2 nanofibres armoured with upconversion nanoparticles, exhibiting intense photoluminescence. These assemblies were subsequently grafted with molecular beacons to produce a biosensor suitable for the detection of specific microRNA and with applications in early cancer detection and point-of-care diagnosis.

Large Hollow Cavity Luminous Nanoparticles with Near-Infrared Persistent Luminescence and Tunable Sizes for Tumor Afterglow Imaging and Chemo-/Photodynamic Therapies

Persistent luminous nanoparticles (PLNPs) have been capturing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits ( e.g., zero-autofluorescence background, high signal-to-noise ratio). Although there are quite some synthetic methodologies to synthesize PLNPs, those for constructing functional structured PLNPs remain largely unexplored. Herein we report the design principle, synthesis route, and proof-of-concept applications of hollow structured PLNPs with near-infrared (NIR) persistent luminescence, namely afterglow, and tunable sizes for tumor afterglow imaging and chemical/photodynamic therapies. The design principle leverages on the crystallization of the immobilized parent ions on the purgeable carbon spheres. This strategy provides large and size-tunable hollow cavities to PLNPs after calcination. Building on the hollow cavity of PLNPs, high chemical drug (DOX) or photosensitizer (Si-Pc) loading can be achieved. The DOX/Si-Pc-loaded hollow PLNPs exhibit efficient tumor suppression based on the features of large cavity and afterglow of PLNPs. These hollow structured PLNPs, like traditional solid PLNPs, are quite stable and can be repeatedly activated, and particularly can selectively target tumor lesion, permitting rechargeable afterglow imaging in living mice. Our research supplies a strategy to synthesize hollow structured PLNPs, and hopefully it could inspire other innovative structures for cancer theranostics.

Theranostic micelles based on upconversion nanoparticles for dual-modality imaging and photodynamic therapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is frequently metastatic once diagnosed and less likely to respond to curative surgery, emphasizing the need for the development of more sensitive and effective diagnostic and therapeutic strategies. Epithelial cell adhesion molecule (EpCAM) is deemed as the biomarker of cancer stem cells (CSCs), which are mainly responsible for the recurrence, metastasis and prognosis of HCC. In this study, we discuss the use of mitoxantrone (MX), an antitumor drug and a photosensitizer, for designing upconversion nanoparticle-based micelles grafted with the anti-EpCAM antibody, for dual-modality magnetic resonance/upconversion luminescence (MR/UCL)-guided synergetic chemotherapy and photodynamic therapy (PDT). The obtained micelles exhibit good biocompatibility, high specificity to HCC cells and superior fluorescent/magnetic properties in vitro. In vivo results demonstrate that the targeted micelles exhibited much better MR/UCL imaging qualities compared to the nontargeted micelles after the intravenous injection. More importantly, PEGylated UCNP micelles loaded with MX and grafted with anti-EpCAM antibody, denoted as anti-EpCAM-UPGs-MX, showcased the most effective synergetic antitumor efficacy compared with other treatment groups both in vitro and vivo. The remarkable antitumor effect, coupled with superior simultaneous dual-modality MR/UCL imaging as well as good biocompatibility and negligible toxicity, makes the UPG micelles promising for future translational research in HCC diagnosis and therapy.

A unique nanogel-based platform for enhanced dual mode tumor MR/CT imaging

Alginate nanogels loaded with gold nanoparticles and gadolinium can be synthesized via a nanoparticle-crosslinking approach for enhanced tumor MR/CT imaging.

Strategies for Preparing Albumin-based Nanoparticles for Multifunctional Bioimaging and Drug Delivery

Biosafety is the primary concern in clinical translation of nanomedicine. As an intrinsic ingredient of human blood without immunogenicity and encouraged by its successful clinical application in Abraxane, albumin has been regarded as a promising material to produce nanoparticles for bioimaging and drug delivery. The strategies for synthesizing albumin-based nanoparticles could be generally categorized into five classes: template, nanocarrier, scaffold, stabilizer and albumin-polymer conjugate. This review introduces approaches utilizing albumin in the preparation of nanoparticles and thereby provides scientists with knowledge of goal-driven design on albumin-based nanomedicine.

Production of a fluorescence resonance energy transfer (FRET) biosensor membrane for microRNA detection

MicroRNAs (miRNAs) play a key role in regulating gene expression but can be associated with abnormalities linked to carcinogenesis and tumor progression. Hence there is increasing interest in developing methods to detect these non-coding RNA molecules in the human circulation system. Here, a novel FRET miRNA-195 targeting biosensor, based on silica nanofibers incorporated with rare earth-doped calcium fluoride particles (CaF₂:Yb,Ho@SiO₂) and gold nanoparticles (AuNPs), is reported. The formation of a sandwich structure, as a result of co-hybridization of the target miRNA which is captured by oligonucleotides conjugated at the surface of CaF₂:Yb,Ho@SiO₂ fibers and AuNPs, brings the nanofibers and AuNPs in close proximity and triggers the FRET effect. The intensity ratio of green to red emission, I₅₄₁/I₆₅₀, was found to decrease linearly upon increasing the concentration of the target miRNA and this can be utilized as a standard curve for quantitative determination of miRNA concentration. This assay offers a simple and convenient method for miRNA quantification, with the potential for rapid and early clinical diagnosis of diseases such as breast cancer.

Gadolinium-based nanoscale MRI contrast agents for tumor imaging

Gadolinium-based nanoscale magnetic resonance imaging (MRI) contrast agents (CAs) have gained significant momentum as a promising nanoplatform for detecting tumor tissue in medical diagnosis, due to their favorable capability of enhancing the longitudinal relaxivity (r₁) of individual gadolinium ions, delivering to the region of interest a large number of gadolinium ions, and incorporating different functionalities. This mini-review highlights the latest developments and applications, and simultaneously gives some perspectives for their future development.

Nanoparticle Functionalization and Its Potentials for Molecular Imaging

Functionalization enhances the properties and characteristics of nanoparticles through surface modification, and enables them to play a major role in the field of medicine. In molecular imaging, quality functional images are required with proper differentiation which can be seen with high contrast to obtain viable information. This review article discusses how functionalization enhances molecular imaging and enables multimodal imaging by which images with combination of functions particular to each modality can be obtained. This also explains how nanoparticles interacting at molecular level, when functionalized with molecules can target the cells of interest or substances with high specificity, reducing background signal and allowing simultaneous therapies to be carried out while imaging. Functionalization allows imaging for a prolonged period and enables to track the cells over a period of time. Recent researches and progress in functionalizing the nanoparticles to specifically enhance bioimaging with different modalities and their applications are reviewed in this article.

Renal Clearable Ag Nanodots for in Vivo Computer Tomography Imaging and Photothermal Therapy

Albumin-stabilized Ag nanodots (ANDs) are prepared by a one-step biomineralization method. The highly crystallized nanodots have ultrasmall sizes (approximately 5.8 nm) and robust X-ray attenuation (5.7313 HU per mM Ag). The unlabeled ANDs are directly excreted from the body via the urine after in vivo X-ray computer tomography (CT) imaging application. ANDs could be used as CT imaging agents and effective photothermal therapy agents. Tumor growth inhibition reaches 90.2% after photothermal treatment with ANDs. ANDs are promising tools for in vivo CT imaging and clearable near-infrared-triggered theranostic agents.

Green Synthesis of Sub-10 nm Gadolinium-Based Nanoparticles for Sparkling Kidneys, Tumor, and Angiogenesis of Tumor-Bearing Mice in Magnetic Resonance Imaging

Gadolinium (Gd)-based nanoparticles are known for their high potential in magnetic resonance imaging (MRI). However, further MRI applications of these nanoparticles are hampered by their relatively large sizes resulting in poor organ/tumor targeting. In this study, ultrafine sub-10 nm and biocompatible Gd-based nanoparticles are synthesized in a bioinspired, environmentally benign, and straightforward fashion. This novel green synthetic strategy is developed for growing dextran-coated Gd-based nanoparticles (GdNPs@Dex). The as-prepared GdNPs@Dex is not only biocompatible but also stable with a sub-10 nm size. It exhibits higher longitudinal and transverse relaxivities in water (r₁ and r₂ values of 5.43 and 7.502 s^-1 × 10^-3 m^-1 of Gd³⁺ , respectively) than those measured for Gd-DTPA solution (r₁ and r₂ values of 3.42 and 3.86 s^-1 × 10^-3 m^-1 of Gd³⁺ , respectively). In vivo dynamic T₁ -weighted MRI in tumor-bearing mice shows GdNPs@Dex can selectively target kidneys and tumor, in addition to liver and spleen. GdNPs@Dex is found particularly capable for determining the tumor boundary with clearly enhanced tumor angiogenesis. GdNPs@Dex is also found cleared from body gradually mainly via hepatobiliary and renal processing with no obvious systemic toxicity. With this green synthesis strategy, the sub-10 nm GdNPs@Dex presents promising potentials for translational biomedical imaging applications.

Site-Specific Biomimetic Precision Chemistry of Bimodal Contrast Agent with Modular Peptides for Tumor-Targeted Imaging

Various biomimetic nanoparticles have been fabricated for cancer nanotheranostics with a diverse range of proteins. However, the operating mechanisms of these reactions are still unclear, especially on the interaction between metal ions and protein, the precise binding sites, and the existence format of nanoparticles. Assuming the shortening of the amino acids sequence into several, namely short peptides, it would be much easier to investigate the biomimetic reaction mechanism. In this study, a modular peptide, possessing Au³⁺ ion coordination motifs and a Gd³⁺ ion chelation sequence, is designed and synthesized. This peptide is experimentally found effective in site-specific biomimetic synthesis of paramagnetic fluorescent gold nanoclusters (pAuNCs) with a quantum yield of 6.8%, deep red emission at 676 nm, and potent relaxivity. The gel electrophoresis result declares that the two imaging motifs in pAuNCs are quite stable. In vivo fluorescence-magnetic resonance bimodal imaging show significant tumor enhancement by pAuNCs in tumor-bearing mice. In vivo biodistribution and toxicity studies reveal that pAuNCs can be gradually cleared from the body without damage. This study presents a modular peptide that can incubate multifunctional nanoparticles in a biomimetic fashion and hopefully provides a strategy for the investigation of the mechanism of protein-mediated biomimetic synthesis.

Size-tunable NaGdF4 nanoparticles as T2 contrast agents for high-field magnetic resonance imaging

It is important to get high-quality magnetic resonance images at high magnetic field (>3 T) for medical diagnoses.

Protein/peptide-templated biomimetic synthesis of inorganic nanoparticles for biomedical applications

Currently, protein/peptide-based biomimetic mineralization has been demonstrated to be an efficient and promising strategy for synthesis of inorganic/metal nanoparticles (NPs) for bioapplications.

Origin of Blue-Green Emission in α-Zn2P2O7 and Local Structure of Ln3+ Ion in α-Zn2P2O7:Ln3+ (Ln = Sm, Eu): Time-Resolved Photoluminescence, EXAFS, and DFT Measurements

Considering the fact that pyrophosphate-based hosts are in high demand for making highly efficient luminescence materials, we doped two visible lanthanide ions, viz. Sm³⁺ and Eu³⁺, in Zn₂P₂O₇. Interestingly, it was oberved that pure Zn₂P₂O₇ displayed blue-green dual emission on irradiation with ultraviolet light. Emission and lifetime spectroscopy shows the presence of defects in pyrophosphate samples which are responsible for such emission. DFT calculations clearly pinpointed that the electronic transitions between defect states located at just below the conduction band minimum (arises due to V_O¹⁺ and V_O²⁺ defects) and valence band maximum, as well as impurity states situated in the band gap, can lead to dual emission in the blue-green region, as is also indicated by emission and lifetime spectra. X-ray absorption near edge spectroscopy (XANES) shows the stabilization of europium as well as samarium ion in the +3 oxidation state in α-Zn₂P₂O₇. The fact that α-Zn₂P₂O₇ has two different coordination numbers for zinc ions, i.e. five- and six-coordinate, the study of dopant ion distribution in this particular matrix will be an important step in realizing a highly efficient europium- and samarium-based red-emitting phosphor. Time resolved photoluminescence (TRPL) shows that both of these ions are heterogeneously distributed between five- and six-coordinated Zn²⁺ sites and it is the six-coordinated Zn²⁺ site which is the most favorable for lanthanide ion doping. Extended X-ray absorption fine structure (EXAFS) measurements also suggested that a six-coordinated zinc ion is the preferred site occupied by trivalent lanthanide ions, which is in complete agreement with TRPL results. It was observed that there is almost complete transfer of photon energy from Zn₂P₂O₇ to Eu³⁺, whereas this transfer is inefficient and almost incomplete in case of Sm³⁺, which is indeed important information for the realization of pyrophosphate-based tunable phosphors.

A Fibrous Localized Drug Delivery Platform with NIR-Triggered and Optically Monitored Drug Release

Implantable localized drug delivery systems (LDDSs) with intelligent functionalities have emerged as a powerful chemotherapeutic platform in curing cancer. Developing LDDSs with rationally controlled drug release and real-time monitoring functionalities holds promise for personalized therapeutic protocols but suffers daunting challenges. To overcome such challenges, a series of porous Yb(3+)/Er(3+) codoped CaTiO3 (CTO:Yb,Er) nanofibers, with specifically designed surface functionalization, were synthesized for doxorubicin (DOX) delivery. The content of DOX released could be optically monitored by increase in the intensity ratio of green to red emission (I550/I660) of upconversion photoluminescent nanofibers under 980 nm near-infrared (NIR) excitation owing to the fluorescence resonance energy transfer (FRET) effect between DOX molecules and the nanofibers. More importantly, the 808 nm NIR irradiation enabled markedly accelerated DOX release, confirming representative NIR-triggered drug release properties. In consequence, such CTO:Yb,Er nanofibers presented significantly enhanced in vitro anticancer efficacy under NIR irradiation. This study has thus inspired another promising fibrous LDDS platform with NIR-triggered and optics-monitored DOX releasing for personalized tumor chemotherapy.

PEGylated polyethylenimine-entrapped gold nanoparticles loaded with gadolinium for dual-mode CT/MR imaging applications

Aim: To synthesize and characterize cost-efficient polyethylenimine-entrapped gold nanoparticles loaded with gadolinium (Gd@Au PENPs) for dual-mode computed tomography (CT)/magnetic resonance (MR) imaging applications. Materials & methods: PEGylated PEI modified with gadolinium (Gd) chelator (DOTA) was used as a template to synthesize the Gd@Au PENPs and the particles were well characterized in terms of their physicochemical properties, cytotoxicity and performances in CT and MR imaging in vitro and in vivo. Results: The formed Gd@Au PENPs with low cytotoxicity can be used as a highly efficient contrast agent for dual-mode CT/MR imaging of blood pool and major organs of animals. Conclusion: The designed Gd@Au PENPs may be used as a versatile nanoplatform for dual-mode CT/MR imaging of different biological systems.

Upconversion Nanoparticles for Bioimaging and Regenerative Medicine

Nanomaterials are proving useful for regenerative medicine in combination with stem cell therapy. Nanoparticles (NPs) can be administrated and targeted to desired tissues or organs and subsequently be used in non-invasive real-time visualization and tracking of cells by means of different imaging techniques, can act as therapeutic agent nanocarriers, and can also serve as scaffolds to guide the growth of new tissue. NPs can be of different chemical nature, such as gold, iron oxide, cadmium selenide, and carbon, and have the potential to be used in regenerative medicine. However, there are still many issues to be solved, such as toxicity, stability, and resident time. Upconversion NPs have relevant properties such as (i) low toxicity, (ii) capability to absorb light in an optical region where absorption in tissues is minimal and penetration is optimal (note they can also be designed to emit in the near-infrared region), and (iii) they can be used in multiplexing and multimodal imaging. An overview on the potentiality of upconversion materials in regenerative medicine is given.

Paramagnetic albumin decorated CuInS2/ZnS QDs for CD133+ glioma bimodal MR/fluorescence targeted imaging

A sensitive, specific, accurate and biocompatible molecular nanoprobe is constructed, by rational design of the structure and an advanced surface engineering strategy, with MR/fluorescence imaging modalities for CD133⁺ glioma bimodal targeted imaging.

Upconversion Nanoparticles for Bioimaging and Regenerative Medicine

Nanomaterials are proving useful for regenerative medicine in combination with stem cell therapy. Nanoparticles (NPs) can be administrated and targeted to desired tissues or organs and subsequently be used in non-invasive real-time visualization and tracking of cells by means of different imaging techniques, can act as therapeutic agent nanocarriers, and can also serve as scaffolds to guide the growth of new tissue. NPs can be of different chemical nature, such as gold, iron oxide, cadmium selenide, and carbon, and have the potential to be used in regenerative medicine. However, there are still many issues to be solved, such as toxicity, stability, and resident time. Upconversion NPs have relevant properties such as (i) low toxicity, (ii) capability to absorb light in an optical region where absorption in tissues is minimal and penetration is optimal (note they can also be designed to emit in the near-infrared region), and (iii) they can be used in multiplexing and multimodal imaging. An overview on the potentiality of upconversion materials in regenerative medicine is given.