Poly(acrylic acid) modified lanthanide-doped GdVO4 hollow spheres for up-conversion cell imaging, MRI and pH-dependent drug release

Modulation of proteins by rare earth elements as a biotechnological tool

Although rare earth element (REE) complexes are often utilized in bioimaging due to their photo- and redox stability, magnetic and optical characteristics, they are also applied for pharmaceutical applications due to their interaction with macromolecules namely proteins. The possible implications induced by REEs through modification in the function or regulatory activity of the proteins trigger a variety of applications for these elements in biomedicine and biotechnology. Lanthanide complexes have particularly been applied as anti-biofilm agents, cancer inhibitors, potential inflammation inhibitors, metabolic elicitors, and helper agents in the cultivation of unculturable strains, drug delivery, tissue engineering, photodynamic, and radiation therapy. This paper overviews emerging applications of REEs in biotechnology, especially in biomedical imaging, tumor diagnosis, and treatment along with their potential toxic effects. Although significant advances in applying REEs have been made, there is a lack of comprehensive studies to identify the potential of all REEs in biotechnology since only four elements, Eu, Ce, Gd, and La, among 17 REEs have been mostly investigated. However, in depth research on ecotoxicology, environmental behavior, and biological functions of REEs in the health and disease status of living organisms is required to fill the vital gaps in our understanding of REEs applications.

Recent development of pH-responsive theranostic nanoplatforms for magnetic resonance imaging-guided cancer therapy

The acidic characteristic of the tumor site is one of the most well-known features and provides a series of opportunities for cancer-specific theranostic strategies. In this regard, pH-responsive theranostic nanoplatforms that integrate diagnostic and therapeutic capabilities are highly developed. The fluidity of the tumor microenvironment (TME), with its temporal and spatial heterogeneities, makes noninvasive molecular magnetic resonance imaging (MRI) technology very desirable for imaging TME constituents and developing MRI-guided theranostic nanoplatforms for tumor-specific treatments. Therefore, various MRI-based theranostic strategies which employ assorted therapeutic modes have been drawn up for more efficient cancer therapy through the raised local concentration of therapeutic agents in pathological tissues. In this review, we summarize the pH-responsive mechanisms of organic components (including polymers, biological molecules, and organosilicas) as well as inorganic components (including metal coordination compounds, metal oxides, and metal salts) of theranostic nanoplatforms. Furthermore, we review the designs and applications of pH-responsive theranostic nanoplatforms for the diagnosis and treatment of cancer. In addition, the challenges and prospects in developing theranostic nanoplatforms with pH-responsiveness for cancer diagnosis and therapy are discussed.

Highly Sensitive Lanthanide-Doped Nanoparticles-Based Point-of-Care Diagnosis of Human Cardiac Troponin I

Introduction

Methods

Results

Conclusion

Extensive tailoring of REPO4 and REVO4 crystallites via solution processing and luminescence

This article highlighted the recent achievements in crystal engineering of REPO4 and REVO4via solution processing, with an emphasis on solution chemistry, the role of chelate ion, crystallization mechanism and luminescence properties.

Vanadium-based nanomaterials for cancer diagnosis and treatment

In the past few decades, various vanadium compounds have displayed potential in cancer treatment. However, fast clearness in the body and possible toxicity of vanadium compounds has hindered their further development. Vanadium-based nanomaterials not only overcome these limitations, but take advantage of the internal properties of vanadium in photics and magnetics, which enable them as a multimodal platform for cancer diagnosis and treatment. In this paper, we first introduced the basic biological and pharmacological functions of vanadium compounds in treating cancer. Then, the synthesis routes of three vanadium-based nanomaterials were discussed, including vanadium oxides, 2D vanadium sulfides, carbides and nitrides: V_mX_n (X = S, C, N) and water-insoluble vanadium salts. Finally, we highlighted the applications of these vanadium-based nanomaterials as tumor therapeutic and diagnostic agents.

Multifunctional bioactive Nd-Ca-Si glasses for fluorescence thermometry, photothermal therapy, and burn tissue repair

Photothermal therapy (PTT), an emerging tumor treatment technology, has attracted tremendous interest, but excessive heat will cause damage to surrounding healthy tissues. Therefore, in situ temperature monitoring during PTT is of great importance to determine optimal treatment temperature and repair heat-damaged normal tissues. Here, we report the preparation of multifunctional Nd-Ca-Si silicate glasses and glass/alginate composite hydrogels that not only have photothermal property but also emit fluorescence under 808-nm laser irradiation, and its fluorescence intensity is linearly correlated with in situ temperature. With this feature, optimal PTT temperature for effective tumor treatment with minimal normal tissue damage can be obtained. In addition, because of the bioactive silicate components, the composite hydrogel has bioactivity to repair heat damage caused by PTT. This implantable multifunctional material with unique temperature monitoring, photothermal function, and wound healing bioactivity can be used for localized thermal therapy.

Update on the development of molecular imaging and nanomedicine in China: Optical imaging

Molecular imaging has received increased attention worldwide, including in China, because it offers noninvasive characterization of widely diverse clinically significant pathologies. To achieve these goals, nanomedicine has evolved into a broad interdisciplinary field with flexible designs to accommodate and concentrate imaging and therapeutic payloads into pathological cells through selective binding to disease specific cell membrane biomarkers. This concept of personalized medicine reflects the vision of "magic bullets" proposed by German biochemist Paul Ehrlich over 100 years ago. As happening worldwide, Chinese scientists are contributing to this tsunami of science and technologies through impactful national programs and international research collaborations. This review provides a comprehensive update of Chinese innovations to address intractable unmet medical need in China and worldwide in the optical sciences. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging.

Application of rare earth-doped nanoparticles in biological imaging and tumor treatment

Rare earth-doped nanoparticles have been widely used in disease diagnosis, drug delivery, tumor therapy, and bioimaging. Among various bioimaging methods, the fluorescence imaging technology based on the rare earth-doped nanoparticles can visually display the cell activity and lesion evolution in living animals, which is a powerful tool in biological technology and has being widely applied in medical and biological fields. Especially in the band of near infrared (700–1700 nm), the emissions show the characteristics of deep penetration due to low absorption, low photon scattering, and low autofluorescence interference. Furthermore, the rare earth-doped nanoparticles can be endowed with the water solubility, biocompatibility, drug-loading ability, and the targeting ability for different tumors by surface functionalization. This confirms its potential in the cancer diagnosis and treatment. In this review, we summarized the recent progress in the application of rare earth-doped nanoparticles in the field of bioimaging and tumor treatment. The luminescent mechanism, properties, and structure design were also discussed.

Multifunctional Magnetic Resonance Imaging Probes

Magnetic resonance imaging is characterized by high spatial resolution and unsurpassed soft tissue discrimination. Development and characterization of both intrinsic and extrinsic magnetic resonance (MR) imaging probes in the last decade has further strengthened the pivotal role MR imaging holds in the assessment of cancer in preclinical and translational settings. Sophisticated chemical modifications of a variety of nanoparticulate probes hold the potential to deliver valuable multifunctional tools applicable in diagnostics and/or treatment in human oncology. MR imaging suffers from a lack of sensitivity achievable by, e.g., nuclear medicine imaging methods. Advantages of including additional functionality/functionalities in a probe suitable for MR imaging are thus numerous, comprising the addition of fundamentally different imaging information (diagnostics), drug delivery (therapy), or the combination of both (theranostics). In recent years, we have witnessed a plethora of preclinical multimodal or multifunctional imaging probes being published mainly as proof-of-principle studies, yet only a handful are readily applicable in clinical settings. This chapter summarizes recent innovations in the development of multifunctional MR imaging probes and discusses the suitability of these probes for clinical transfer.

In Vivo Tracking of Tissue Engineered Constructs

To date, the fields of biomaterials science and tissue engineering have shown great promise in creating bioartificial tissues and organs for use in a variety of regenerative medicine applications. With the emergence of new technologies such as additive biomanufacturing and 3D bioprinting, increasingly complex tissue constructs are being fabricated to fulfill the desired patient-specific requirements. Fundamental to the further advancement of this field is the design and development of imaging modalities that can enable visualization of the bioengineered constructs following implantation, at adequate spatial and temporal resolution and high penetration depths. These in vivo tracking techniques should introduce minimum toxicity, disruption, and destruction to treated tissues, while generating clinically relevant signal-to-noise ratios. This article reviews the imaging techniques that are currently being adopted in both research and clinical studies to track tissue engineering scaffolds in vivo, with special attention to 3D bioprinted tissue constructs.

Lanthanide-Doped Photoluminescence Hollow Structures: Recent Advances and Applications

Lanthanide-doped nanomaterials have attracted significant attention for their preeminent properties and widespread applications. Due to the unique characteristic, the lanthanide-doped photoluminescence materials with hollow structures may provide advantages including enhanced light harvesting, intensified electric field density, improved luminescent property, and larger drug loading capacity. Herein, the synthesis, properties, and applications of lanthanide-doped photoluminescence hollow structures (LPHSs) are comprehensively reviewed. First, different strategies for the engineered synthesis of LPHSs are described in detail, which contain hard, soft, self-templating methods and other techniques. Thereafter, the relationship between their structure features and photoluminescence properties is discussed. Then, niche applications including biomedicines, bioimaging, therapy, and energy storage/conversion are focused on and superiorities of LPHSs for these applications are particularly highlighted. Finally, keen insights into the challenges and personal prospects for the future development of the LPHSs are provided.

Upconverting LuVO4:Nd3+/Yb3+/Er3+@SiO2@Cu2S Hollow Nanoplatforms for Self-monitored Photothermal Ablation

Self-monitored photothermal therapy (PTT) with minimal collateral damages has emerged as a challenging strategy for antibacterial and cancer treatments, which could be fulfilled via the rational integration of luminescent thermometry and photothermal ablation within a single upconverting (UC) nanoplatform. Herein, 808 nm light-driven dual-functional nanoplatforms LuVO₄:Nd³⁺/Yb³⁺/Er³⁺@SiO₂@Cu₂S were successfully developed using olivelike LuVO₄:Nd³⁺/Yb³⁺/Er³⁺ hollow nanoparticles as the thermal-sensing core and ultrasmall Cu₂S nanoparticles as the photothermal satellite. Irradiated by 808 nm laser, thermal-sensing behaviors of samples were evaluated based on the high-purity Er³⁺ green emissions, while the surface-attached Cu₂S exhibited superior photothermal effects due to the efficient absorption of incident laser and near-infrared emissions from the luminescent core. The feasibility of bifunctional samples acting as self-monitored photothermal agents in subtissues and antibacterial agents against drug-resistant bacteria was separately assessed. Results provide deeper insights into the desirable design of 808 nm-driven multifunctional nanoplatforms with intense UC emission, sensitive thermometry, and effective photothermal conversion toward self-monitored PTT with high therapeutic accuracy.

A gold nanoflower-based traceable drug delivery system for intracellular SERS imaging-guided targeted chemo-phototherapy

Accurate and effective drug delivery in tumor cells significantly improves the curative effect with high drug delivery efficiency, low toxicity and side effects and has become an urgent demand for anticancer therapy. In this paper, a novel traceable and targeted drug delivery nanosystem (i.e. AuNF-nanocarriers) with high drug encapsulation and pH-controlled release was prepared based on gold nanoflowers (AuNFs) for efficient intracellular SERS imaging-guided chemo-phototherapy. SERS-active flower-like gold nanoparticles with large surface area were synthesized first and then modified with Raman and RGD molecules in sequence to prepare bright, traceable and targeted SERS tags of A549 human lung cancer cells. Furthermore, thiolated-PAA (PAA-SH) was synthesized and utilized for the first time to modify the SERS tags with a layer of negative charges for efficient pH-dependent loading and release of the anticancer drug doxorubicin. Based on the A549 human lung cancer cell model, the availability of the proposed AuNF-nanocarriers for efficient intracellular SERS imaging-guided chemo-phototherapy was studied and the results indicate that the AuNF-based drug delivery system exhibited attractive characteristics such as good stability, efficiency and pH-controlled drug loading and release, traceable and targeted delivery, as well as SERS imaging and chemo-phototherapy functions, and shows great potential for powerful SERS-imaging and as a theranostic candidate for precision nanomedicine that could achieve sensitive and accurate tumor detection and therapy.

A novel strategy for thermometry based on the temperature-induced red shift of the charge transfer band edge

We report a novel strategy for optical temperature sensing using the temperature-induced red shift of the charge transfer band (CTB) edge of the VO₄^3- groups in GdVO₄:5% Sm³⁺. Excitation spectra were recorded at a series of temperatures ranging from 300 to 480 K. It is demonstrated that an excitation intensity of around 360 nm corresponding to the tail of the CTB and an excitation intensity of 407.6 nm corresponding to the ⁶H_5/2 → ⁴F_7/2 transition of Sm³⁺ exhibit opposite temperature dependence. Based on this, the relative sensitivity was obtained to be 3313/T² in our investigated temperature range, which is remarkable progress compared with the optical temperature sensors reported previously. We believe that this work broadens the pathway for the design of highly sensitive temperature sensing materials.

Multifunctional GdVO4:Eu core–shell nanoparticles containing 225Ac for targeted alpha therapy and molecular imaging

Development of actinium-225 doped Gd_0.8Eu_0.2VO₄ core–shell nanoparticles as multifunctional platforms for multimodal molecular imaging and targeted radionuclide therapy.

Fabrication of pH-responsive PLGA(UCNPs/DOX) nanocapsules with upconversion luminescence for drug delivery

The integration of anticancer drugs and inorganic nanocrystals in polymer nanocapsules is a widely used strategy to improve their functionality, stability and sustained release. However, the complexity in the preparation of functional nanocapsules and their reproducibility still challenge these promising drug carriers in clinical application. Here we introduce a simple one-step self-assembly strategy to prepare multifunctional nanocapsules based on simultaneous poly (DL-lactic-co-glycolic acid) (PLGA) encapsulation of antitumor drug doxorubicin hydrochloride (DOX) and NaYF4:Yb,Er@NaGdF4 upconversion nanoparticles (UCNPs) for cancer cell imaging and drug delivery. The obtained PLGA(UCNPs/DOX) nanocapsules with a small size of ≈150 nm possessed bright upconversion fluorescence and could act as T 1- weighted contrast agents for magnetic resonance imaging (MRI). Moreover, the PLGA(UCNPs/DOX) nanocapsules exhibited pH-responsive drug releasing behavior, causing the loaded DOX easily releasing at cancer cells, and an obvious cytotoxicity via MTT assay. The endocytosis process of PLGA (UCNPs/DOX) nanocapsules is evaluated using optical microscopy and upconversion fluorescence microscopy. These results demonstrated that the developed PLGA nanocapsules could serve as multifunctional drug delivery systems for cancer imaging and therapy.

Sensing temperature via downshifting emissions of lanthanide-doped metal oxides and salts. A review

Temperature is important because it has an effect on even the tiniest elements of daily life and is involved in a broad spectrum of human activities. That is why it is the most commonly measured physical quantity. Traditional temperature measurements encounter difficulties when used in some emerging technologies and environments, such as nanotechnology and biomedicine. The problem may be alleviated using optical techniques, one of which is luminescence thermometry. This paper reviews the state of luminescence thermometry and presents different temperature read-out schemes with an emphasis on those utilizing the downshifting emission of lanthanide-doped metal oxides and salts. The read-out schemes for temperature include those based on measurements of spectral characteristics of luminescence (band positions and shapes, emission intensity and ratio of emission intensities), and those based on measurements of the temporal behavior of luminescence (lifetimes and rise times). This review (with 140 references) gives the basics of the fundamental principles and theory that underlie the methods presented, and describes the methodology for the estimation of their performance. The major part of the text is devoted to those lanthanide-doped metal oxides and salts that are used as temperature probes, and to the comparison of their performance and characteristics.

Current Advances in Lanthanide-Doped Upconversion Nanostructures for Detection and Bioapplication

Along with the development of science and technology, lanthanide-doped upconversion nanostructures as a new type of materials have taken their place in the field of nanomaterials. Upconversion luminescence is a nonlinear optical phenomenon, which absorbs two or more photons and emits one photon. Compared with traditional luminescence materials, upconversion nanostructures have many advantages, such as weak background interference, long lifetime, low excitation energy, and strong tissue penetration. These interesting nanostructures can be applied in anticounterfeit, solar cell, detection, bioimaging, therapy, and so on. This review is focused on the current advances in lanthanide-doped upconversion nanostructures, covering not only basic luminescence mechanism, synthesis, and modification methods but also the design and fabrication of upconversion nanostructures, like core-shell nanoparticles or nanocomposites. At last, this review emphasizes the application of upconversion nanostructure in detection and bioimaging and therapy. Learning more about the advances of upconversion nanostructures can help us better exploit their excellent performance and use them in practice.

Spectroscopic, structural and in vitro cytotoxicity evaluation of luminescent, lanthanide doped core@shell nanomaterials GdVO4:Eu(3+)5%@SiO2@NH2

The luminescent GdVO4:Eu(3+)5%@SiO2@NH2 core@shell nanomaterials were obtained via co-precipitation method, followed by hydrolysis and co-condensation of silane derivatives: tetraethyl orthosilicate and 3-aminopropyltriethoxysilane. Their effect on human erythrocytes sedimentation and on proliferation of human lung microvascular endothelial cells was examined and discussed. The luminescent nanoparticles were synthesized in the presence of polyacrylic acid or glycerin in order to minimalize the agglomeration and excessive growth of nanostructures. Surface coating with amine functionalized silica shell improved their biocompatibility, facilitated further organic conjugation and protected the internal core. Magnetic measurements revealed an enhanced T1-relaxivity for the synthesized GdVO4:Eu(3+)5% nanostructures. Structure, morphology and average grain size of the obtained nanomaterials were determined by X-ray diffraction, transmission electron microscopy and dynamic light scattering analysis. The qualitative elemental composition of the nanomaterials was established using energy-dispersive X-ray spectroscopy. The spectroscopic characteristic of red emitting core@shell nanophosphors was completed by measuring luminescence spectra and decays. The emission spectra revealed characteristic bands of Eu(3+) ions related to the transitions (5)D0-(7)F0,1,2,3,4 and (5)D1-(7)F1. The luminescence lifetimes consisted of two components, associated with the presence of Eu(3+) ions located at the surface of the crystallites and in the bulk.

Lanthanide-Doped Upconversion Nanoparticles: Emerging Intelligent Light-Activated Drug Delivery Systems

The development of drug delivery systems (DDSs) using near infrared (NIR) light and upconversion nanoparticles (UCNPs) has generated intensive interest over the past five years. These NIR-initiated DDSs not only offer a high degree of spatial and temporal determination of therapeutic release but also provide precise control over the released dosage. Furthermore, these nanoplatforms confer several advantages over conventional light-based DDSs-NIR offers better tissue penetration depth and a reduced risk of cellular photo-damage caused by exposure to light at high-energy wavelengths (e.g., ultraviolet light, <400 nm). The development of DDSs that can be activated by low intensity NIR illumination is highly desirable to avoid exposing living tissues to excessive heat that can limit the in vivo application of these DDSs. This encompasses research in three directions: (i) enhancing the quantum yield of the UCNPs; (ii) incorporation of photo-responsive materials with red-shifted absorptions into the UCNPs; and (iii) tuning the UCNPs excitation wavelength. This review focuses on recent advances in the development of NIR-initiated DDS, with emphasis on the use of photo-responsive compounds and polymeric materials conjugated onto UCNPs. The challenges that limit UCNPs clinical applications, alongside with the aforementioned techniques that have emerged to overcome these limitations, are highlighted.

Construction of pH-responsive and up-conversion luminescent NaYF₄:Yb³⁺/Er³⁺@SiO₂@PMAA nanocomposite for colon targeted drug delivery

Colon-targeted drug delivery system has attracted much interest because it can improve therapeutic efficacy and reduce the side effect in practical clinic. Herein, we constructed a multifunctional drug delivery system with colonic targeting and tracking by up-conversion (UC) luminescence based on core-shell structured NaYF4:Yb(3+)/Er(3+)@SiO2@PMAA nanocomposite. The resultant materials exhibited bright UC luminescence, pH-responsive property and excellent biocompatibility. The drug release behaviors in different pH environment were investigated using 5-aminosalicylic acid (5-ASA) as a model drug. The 5-ASA molecules release from NaYF4:Yb(3+)/Er(3+)@SiO2@PMAA nanocomposite exhibit a significant pH-responsive colon targeted property, i.e., a little amount of drug release in simulated gastric fluid (SGF, pH = 1.2) but a large amount of drug release in simulated colonic fluid (SCF, pH = 7.4) Moreover, the drug release process could be monitored by the change of UC emission intensity. These results implied that the multifunctional nanocomposite is a promising drug carrier for targeted release of 5-ASA in the colon.

Tunable photoluminescence and magnetic properties of Dy(3+) and Eu(3+) doped GdVO4 multifunctional phosphors

A series of Dy(3+) or/and Eu(3+) doped GdVO4 phosphors were successfully prepared by a simple hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the as-prepared samples are pure tetragonal phase GdVO4, taking on nanoparticles with an average size of 45 nm. Under ultraviolet (UV) light excitation, the individual Dy(3+) or Eu(3+) ion activated GdVO4 phosphors exhibit excellent emission properties in their respective regions. The mechanism of energy transfer from the VO4(3-) group and the charge transfer band (CTB) to Dy(3+) and Eu(3+) ions is proposed. Color-tunable emissions in GdVO4:Dy(3+),Eu(3+) phosphors are realized through adopting different excitation wavelengths or adjusting the appropriate concentration of Dy(3+) and Eu(3+) when excited by a single excitation wavelength. In addition, the as-prepared samples show paramagnetic properties at room temperature. This kind of multifunctional color-tunable phosphor has great potential applications in the fields of photoelectronic devices and biomedical sciences.

Syntheses and biomedical applications of hollow micro-/nano-spheres with large-through-holes

This review mainly discussed the syntheses and biomedical applications of hollow micro-/nano-spheres with large-through-holes in shells.

Facile synthesis of flower-shaped Au/GdVO4:Eu core/shell nanoparticles by using citrate as stabilizer and complexing agent

The synthesis of metal/rare-earth core/shell hetero-nanostructures through directly coating rare-earth compound onto the surface of Au nanocrystals.

Multifunctional Gd,Ce,Tb co-doped β-tricalcium phosphate porous nanospheres for sustained drug release and bioimaging

Uniform Gd,Ce,Tb co-doped β-TCP porous nanospheres are prepared by a solvothermal method using (CH₃O)₃PO as the organic phosphorus source and they demonstrate multifunctional bioapplications.

Personalizing Biomaterials for Precision Nanomedicine Considering the Local Tissue Microenvironment

New advances in (nano)biomaterial design coupled with the detailed study of tissue-biomaterial interactions can open a new chapter in personalized medicine, where biomaterials are chosen and designed to match specific tissue types and disease states. The notion of a "one size fits all" biomaterial no longer exists, as growing evidence points to the value of customizing material design to enhance (pre)clinical performance. The complex microenvironment in vivo at different tissue sites exhibits diverse cell types, tissue chemistry, tissue morphology, and mechanical stresses that are further altered by local pathology. This complex and dynamic environment may alter the implanted material's properties and in turn affect its in vivo performance. It is crucial, therefore, to carefully study tissue context and optimize biomaterials considering the implantation conditions. This practice would enable attaining predictable material performance and enhance clinical outcomes.

Defect-related luminescent mesoporous silica nanoparticles employed for novel detectable nanocarrier

Uniform and well-dispersed walnut kernel-like mesoporous silica nanoparticles (MSNs) with diameters about 100 nm have been synthesized by a templating sol-gel route. After an annealing process, the as-obtained sample (DLMSNs) inherits the well-defined morphology and good dispersion of MSNs, and exhibits bright white-blue luminescence, higher specific surface area and pore volume, and better biocompatibility. The drug loading and release profiles show that DLMSNs have high drug loading capacity, and exhibit an initial burst release followed by a slow sustained release process. Interestingly, the luminescence intensity of the DLMSNs-DOX system increases gradually with the increase of cumulative released DOX, which can be verified by the confocal laser scanning images. The drug carrier DLMSNs can potentially be applied as a luminescent probe for monitoring the drug release process. Moreover, the DLMSNs-DOX system exhibits potent anticancer effect against three kinds of cancer cells (HeLa, MCF-7, and A549 cells).

Lanthanide-doped luminescent nano-bioprobes for the detection of tumor markers

Sensitive and specific biodetection of tumor markers is essential for early-stage cancer diagnosis and therapy, and will ultimately increase the patient survival rate. As a new generation of luminescent bioprobes, lanthanide (Ln(3+))-doped inorganic luminescent nanoparticles have attracted considerable interest for a variety of biomedical applications due to their superior physicochemical properties. In this feature article, we provide a brief overview of the most recent advances in the development of Ln(3+)-doped luminescent nano-bioprobes and their promising applications for in vitro detection of tumor markers with an emphasis on the establishment of state-of-the-art assay techniques, such as heterogeneous time-resolved (TR) luminescent bioassay, dissolution-enhanced luminescent bioassay, upconversion (UC) luminescent bioassay, homogeneous TR Förster resonance energy transfer (TR-FRET) and UC-FRET bioassays. Some future prospects and efforts towards this emerging field are also envisioned.

One-step synthesis of gradient gadolinium ironhexacyanoferrate nanoparticles: a new particle design easily combining MRI contrast and photothermal therapy

A one-step synthesis of Prussian blue nanoparticles possessing a concentration gradient of Gd3+ counterions, g-Gd-PB, has been developed, and the potential for the particles to perform as both MRI positive contrast agents and photothermal therapy agents is demonstrated. The synthesis of potassium/gadolinium ironhexacyanoferrate is performed under increasing concentration of Gd3+ ions forming particles with a higher concentration of gadolinium toward the outer layers. The proton relaxivity (r1) measured for the particles is 12.3 mM(-1) s(-1), and T1 weighted images of phantoms containing the particles show their potential as MRI contrast agents. In addition, the Prussian blue host can rapidly and efficiently convert energy from near-IR light into thermal energy, allowing g-Gd-PB to be used as a photothermal therapy agent. The photothermal properties are demonstrated by measuring temperature changes of particle suspensions under irradiation and by photothermal ablation of CCRF-CEM cancer cells.

Current advances in lanthanide ion (Ln3+)-based upconversion nanomaterials for drug delivery

This review mainly focuses on the recent advances in various chemical syntheses of Ln³⁺-based upconversion nanomaterials, with special emphasis on their application in stimuli-response controlled drug release and subsequent therapy.

Nano- and micro-sized rare-earth carbonates and their use as precursors and sacrificial templates for the synthesis of new innovative materials

Rare-earth carbonate nano- and micro-materials are reviewed, focusing on factors that influence the morphology and luminescence, as well as their applications as precursors and sacrificial templates for other materials.

Nanoparticle conversion chemistry: Kirkendall effect, galvanic exchange, and anion exchange

Conversion chemistry is a rapidly maturing field, where chemical conversion of template nanoparticles (NPs) into new compositions is often accompanied by morphological changes, such as void formation. The principles and examples of three major classes of conversion chemical reactions are reviewed: the Kirkendall effect for metal NPs, galvanic exchange, and anion exchange, each of which can result in void formation in NPs. These reactions can be used to obtain complex structures that may not be attainable by other methods. During each kind of conversion chemical reaction, NPs undergo distinct chemical and morphological changes, and insights into the mechanisms of these reactions will allow for improved fine control and prediction of the structures of intermediates and products. Conversion of metal NPs into oxides, phosphides, sulphides, and selenides often occurs through the Kirkendall effect, where outward diffusion of metal atoms from the core is faster than inward diffusion of reactive species, resulting in void formation. In galvanic exchange reactions, metal NPs react with noble metal salts, where a redox reaction favours reduction and deposition of the noble metal (alloying) and oxidation and dissolution of the template metal (dealloying). In anion exchange reactions, addition of certain kinds of anions to solutions containing metal compound NPs drives anion exchange, which often results in significant morphological changes due to the large size of anions compared to cations. Conversion chemistry thus allows for the formation of NPs with complex compositions and structures, for which numerous applications are anticipated arising from their novel catalytic, electronic, optical, magnetic, and electrochemical properties.