Controlling trapping states on selective theranostic core@shell (NaYF4:Yb,Tm@TiO2-ZrO2) nanocomplexes for enhanced NIR-activated photodynamic therapy against breast cancer cells

Diagnosis and treatment status of inoperable locally advanced breast cancer and the application value of inorganic nanomaterials

Locally advanced breast cancer (LABC) is a heterogeneous group of breast cancer that accounts for 10-30% of breast cancer cases. Despite the ongoing development of current treatment methods, LABC remains a severe and complex public health concern around the world, thus prompting the urgent requirement for innovative diagnosis and treatment strategies. The primary treatment challenges are inoperable clinical status and ineffective local control methods. With the rapid advancement of nanotechnology, inorganic nanoparticles (INPs) exhibit a potential application prospect in diagnosing and treating breast cancer. Due to the unique inherent characteristics of INPs, different functions can be performed via appropriate modifications and constructions, thus making them suitable for different imaging technology strategies and treatment schemes. INPs can improve the efficacy of conventional local radiotherapy treatment. In the face of inoperable LABC, INPs have proposed new local therapeutic methods and fostered the evolution of novel strategies such as photothermal and photodynamic therapy, magnetothermal therapy, sonodynamic therapy, and multifunctional inorganic nanoplatform. This article reviews the advances of INPs in local accurate imaging and breast cancer treatment and offers insights to overcome the existing clinical difficulties in LABC management.

Photon Upconversion in Small Molecules

Upconversion (UC) is a process that describes the emission of shorter-wavelength light compared to that of the excitation source. Thus, UC is also referred to as anti-Stokes emission because the excitation wavelength is longer than the emission wavelength. UC materials are used in many fields, from electronics to medicine. The objective of using UC in medical research is to synthesize upconversion nanoparticles (UCNPs) composed of a lanthanide core with a coating of adsorbed dye that will generate fluorescence after excitation with near-infrared light to illuminate deep tissue. Emission occurs in the visible and UV range, and excitation mainly in the near-infrared spectrum. UC is observed for lanthanide ions due to the arrangement of their energy levels resulting from f-f electronic transitions. Organic compounds and transition metal ions are also able to form the UC process. Biocompatible UCNPs are designed to absorb infrared light and emit visible light in the UC process. Fluorescent dyes are adsorbed to UCNPs and employed in PDT to achieve deeper tissue effects upon irradiation with infrared light. Fluorescent UCNPs afford selectivity as they may be activated only by illumination of an area of diseased tissue, such as a tumor, with infrared light and are by themselves atoxic in the absence of infrared light. UCNP constructs can be monitored as to their location in the body and uptake by cancer cells, aiding in evaluation of exact doses required to treat the targeted cancer. In this paper, we review current research in UC studies and UCNP development.

Poly(allylamine)-copper(II) coordination complex grafted on core@shell upconversion nanoparticles for ultrafast and sensitive determination of the phytohormone salicylic acid in plant extracts

Salicylic acid (SA) is a phenolic phytohormone with critical roles in plant growth regulation and resistance to biotic and abiotic stress. Since low SA concentrations can modulate many plant biochemical responses, innovative analytical tools are required to deeply understand its activity and to control its exogenous application in modern agricultural systems. Herein, a NIR-activated composite based on NaYF₄:Yb,Er@NaYF₄ core@shell upconversion nanoparticles decorated with the poly(allylamine)-Cu(II) complex [UCNPs-PAAm-Cu(II)] was developed to sensitively determine the SA molecule in plant-derived samples. Accordingly, the PAAm-Cu(II) complex grafted on the UCNPs induces a strategic charge transfer band which triggers a quenching process through a resonance energy transfer (RET) mechanism. Such process is gradually deactivated upon the addition of SA and the consequent formation of the SA-Cu(II) complex, allowing a luminescence recovery in the 1-800 nM linear range. This mechanism is promoted by the strong stability of the SA-Cu(II) complex (log β_2-SA/Cu = 19.01) which is over twelve orders of magnitude stronger than the PAAm-Cu²⁺ counterpart. Furthermore, the equilibrium and kinetic studies on the involved mononuclear Cu²⁺ complexes formation permitted instantaneous analytical responses and excellent selectivity against other representative phytohormones and metallic cations. The reliability of this method was demonstrated by determining the SA content of some edible fruits and vegetables comprising apple, lemon, kiwi, tomato, and cucumber, whose concentrations ranged from 0.30 to 2.99 μg g^-1, with percent recoveries between 94.6 to 102.3%. Thereby, the reported nanocomplex can help to understand the SA activity in plants with significant applications in crop yield improvement and food quality assessment.

Application of lanthanide-doped upconversion nanoparticles for cancer treatment: a review

With the excellent ability to transform near-infrared light to localized visible or UV light, thereby achieving deep tissue penetration, lanthanide ion-doped upconversion nanoparticles (UCNP) have emerged as one of the most striking nanoscale materials for more effective and safer cancer treatment. Up to now, UCNPs combined with photosensitive components have been widely used in the delivery of chemotherapy drugs, photodynamic therapy and photothermal therapy. Applications in these directions are reviewed in this article. We also highlight microenvironmental tumor monitoring and precise targeted therapies. Then we briefly summarize some new trends and the existing challenges for UCNPs. We hope this review can provide new ideas for future cancer treatment based on UCNPs.

Nanobodies as efficient drug-carriers: Progress and trends in chemotherapy

Nanobodies (Nb) have a promising future as a part of next generation chemodrug delivery systems. Nb, or VHH, are small (15 kDa) monomeric antibody fragments consisting of the antigen binding region of heavy chain antibodies. Heavy chain antibodies are naturally produced by camelids, however the structure of their VHH regions can be readily reproduced in industrial expression systems, such as bacteria or yeast. Due to their small size, high solubility, remarkable stability, manipulatable characteristics, excellent in vivo tissue penetration, conjugation advantages, and ease of production, Nb have many advantages when compared against their antibody precursors. In this review, we discuss the generation and selection of Nbs via phage display libraries for easy screening, and the conjugation techniques involved in creating target-specific nanocarriers. Furthermore, we provide a comprehensive overview of recent developments and perspectives in the field of Nb drug conjugates (NDCs) and Nb-based drug vehicles (NDv) with respect to antitumor therapeutics.

Reactive Oxygen Species-Based Nanomaterials for Cancer Therapy

Nanotechnology advances in cancer therapy applications have led to the development of nanomaterials that generate cytotoxic reactive oxygen species (ROS) specifically in tumor cells. ROS act as a double-edged sword, as they can promote tumorigenesis and proliferation but also trigger cell death by enhancing intracellular oxidative stress. Various nanomaterials function by increasing ROS production in tumor cells and thereby disturbing their redox balance, leading to lipid peroxidation, and oxidative damage of DNA and proteins. In this review, we outline these mechanisms, summarize recent progress in ROS-based nanomaterials, including metal-based nanoparticles, organic nanomaterials, and chemotherapy drug-loaded nanoplatforms, and highlight their biomedical applications in cancer therapy as drug delivery systems (DDSs) or in combination with chemodynamic therapy (CDT), photodynamic therapy (PDT), or sonodynamic therapy (SDT). Finally, we discuss the advantages and limitations of current ROS-mediated nanomaterials used in cancer therapy and speculate on the future progress of this nanotechnology for oncological applications.

Inorganic Nanoparticles Applied for Active Targeted Photodynamic Therapy of Breast Cancer

Photodynamic therapy (PDT) is an alternative modality to conventional cancer treatment, whereby a specific wavelength of light is applied to a targeted tumor, which has either a photosensitizer or photochemotherapeutic agent localized within it. This light activates the photosensitizer in the presence of molecular oxygen to produce phototoxic species, which in turn obliterate cancer cells. The incidence rate of breast cancer (BC) is regularly growing among women, which are currently being treated with methods, such as chemotherapy, radiotherapy, and surgery. These conventional treatment methods are invasive and often produce unwanted side effects, whereas PDT is more specific and localized method of cancer treatment. The utilization of nanoparticles in PDT has shown great advantages compared to free photosensitizers in terms of solubility, early degradation, and biodistribution, as well as far more effective intercellular penetration and uptake in targeted cancer cells. This review gives an overview of the use of inorganic nanoparticles (NPs), including: gold, magnetic, carbon-based, ceramic, and up-conversion NPs, as well as quantum dots in PDT over the last 10 years (2009 to 2019), with a particular focus on the active targeting strategies for the PDT treatment of BC.

Perspectives of photodynamic therapy in biotechnology

Photodynamic therapy (PDT) is a current and innovative technique that can be applied in different areas, such as medical, biotechnological, veterinary, among others, both for the treatment of different pathologies, as well as for diagnosis. It is based on the action of light to activate photosensitizers that will perform their activity on target tissues, presenting high sensitivity and less adverse effects. Therefore, knowing that biotechnology aims to use processes to develop products aimed at improving the quality of life of human and the environment, and optimizing therapeutic actions, researchers have been used PDT as a tool of choice. This review aims to identify the impacts and perspectives and challenges of PDT in different areas of biotechnology, such as health and agriculture and oncology. Our search demonstrated that PDT has an important impact around oncology, minimizing the adverse effects and resistance to chemotherapeutic to the current treatments available for cancer. Veterinary medicine is another area with continuous interest in this therapy, since studies have shown promising results for the treatment of different animal pathologies such as Bovine mastitis, Malassezia, cutaneous hemangiosarcoma, among others. In agriculture, PDT has been used, for example, to remove traces of antibiotics of milk. The challenges, in general, of PDT in the field of biotechnology are mainly the development of effective and non-toxic or less toxic photosensitizers for humans, animals and plants. We believe that there is a current and future potential for PDT in different fields of biotechnology due to the existing demand.

Transforming lanthanide and actinide chemistry with nanoparticles

Lanthanides and actinides are used in a wide variety of applications, from energy production to life sciences. To address toxicity issues due to the chemical, and often radiological, properties of these elements, methods to quantify and recover them from industrial waste are necessary. When used in biomedicine, lanthanides and actinides are incorporated in compounds that show promising therapeutic and/or bioimaging properties, but lack robust strategies to target cancer and other pathologies. Furthermore, current decorporation protocols to respond to accidental actinide exposure rely on intravenous injections of soluble chelating agents, which are inefficient for treatment of inhaled radionuclides trapped in lungs. In recent years, nanoparticles have emerged as powerful tools in both industry and clinical settings. Because some inorganic nanoparticles are sensitive to external stimuli, such as light and magnetic fields, they can be used as building blocks for sensitive bioassays and separation techniques. In addition, nanoparticles can be functionalized with multiple ligands and act as carriers for selective delivery of therapeutic and contrast agents. This review summarizes and discusses recent progress on the use of nanoparticles in lanthanide and actinide chemistry. We examine different types of nanoparticles based on composition, functionalization, and properties, and we critically analyze their performance in a comparative mode. Our focus is two-pronged, including the nanoparticles free of lanthanides and actinides that are used for the detection, separation, or decorporation of f-block elements, as well as the nanoparticles that enhance the inherent properties of lanthanides and actinides for therapeutics, imaging and catalysis.

Novel anti-HER2 peptide-conjugated theranostic nanoliposomes combining NaYF4:Yb,Er nanoparticles for NIR-activated bioimaging and chemo-photodynamic therapy against breast cancer

Herein, we reported the fabrication of novel peptide-conjugated ligand-targeted nanoliposomes (LTLs) for chemo-photodynamic therapy against HER2-positive breast cancer. The LTL core was utilized for encapsulating doxorubicin (DOX) for chemotherapy, and methylene blue (MB) attached NaYF₄:Yb,Er upconversion nanoparticles (UCNPs) for NIR-activated bioimaging and leveraging its visible emission for photoexciting MB for enhanced photodynamic therapy (PDT). The specificity of our LTLs was achieved by conjugating a newly discovered anti-HER2 peptide screened from a phage display peptide library. The high selectivity of the peptide-conjugated LTLs was confirmed by confocal imaging of SKBR-3 (HER2-positive) and MCF-7 (HER2-negative) breast cancer cell lines, illustrating its target-specific nature. The energy transfer from UCNPs to MB was verified, thus enabling the generation of reactive oxygen species upon activation with a 975 nm laser source (0.60 W cm^-2) under 5 min continuous excitation. A significant decline in the cell viability by 95% was observed using chemo-photodynamic combinational therapy, whereas for chemo-drug alone and PDT alone, the cell proliferation declined by 77% and 84%, respectively. Furthermore, we demonstrated an improved uptake of the LTLs inside a 3D model of SKBR-3 tumor spheroids, where the spheroid cell viability was suppressed by 66% after the use of combinational therapy. Thus, our results suggest great prospective use of theranostic LTLs for breast cancer management.

A Turn-On Luminescence Method for Phosphate Determination Based on Fast Green-Functionalized ZrO2:Yb,Er@ZrO2 Core@Shell Upconversion Nanoparticles

The development of practical and sensitive tools for detecting phosphate deficiency could facilitate engineering approaches to enhance crop yield and quality in phosphate-stressed environments, reducing the misuse of nonrenewable fertilizers and their consequent ecological impact. Herein, a 975 nm-activated method based on ZrO₂:Yb,Er@ZrO₂ core@shell upconversion nanoparticles is presented for rapid visualization and determination of the phosphate ions in aqueous solutions and extracts. At optimized thickness, the nondoped ZrO₂ shell not only enhances the emission of the ZrO₂:Yb,Er but also provides an active surface for the intense interaction with the phosphate group, allowing a "label-free" determination that avoids the use of additional phosphate-recognizing elements like ligands or antibodies. According to the experimental evidence, the optical output of the ZrO₂:Yb,Er@ZrO₂ nanoparticles specifically matches with the absorption spectrum of the fast green alimentary dye (FG) electrostatically attached to the nanoparticle surface, activating the Förster resonance energy transfer (FRET) and thereby the upconversion luminescence quenching. Upon addition of the phosphate ions and the covalent interaction with the ZrO₂:Yb,Er@ZrO₂-FG nanocomplex, the FG is gradually removed, displaying a fast and reproducible "turn-on" luminescence which allows measurements in a few minutes. This rapid response is due to the stronger coordination between the ZrO₂ shell and the phosphate compared to the FG molecules (-31.97 and -5.99 eV, respectively). The detection method was then effectively modulated in a 20-1000 nM linear response range without interfering effects of commonly coexisting ions, achieving a detection limit up to 15 times lower than that obtained with the conventionally used colorimetric methods.