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Non-immunoglobulin-based scaffold proteins (SPs) represent one of the key therapeutic target-specific and high-affinity binders in modern medicine. Among their cellular targets are signaling receptors, in particular, receptor tyrosine kinases, whose dysfunction leads to the development of cancer and other serious diseases. Successful applications of SPs have been reported for HER receptor type 2 (HER2), a member of the human epidermal growth factor receptor family that regulates cell growth and differentiation. To extend the blood residence of SPs and prevent their high accumulation in the kidneys, these proteins are often fused with serum albumin. Promising results for HER2-binding activity were obtained for SP G3 from the DARPins (Designed Ankyrin Repeat Proteins) family fused with an albumin-binding domain (ABD). Interestingly, the detected HER2–G3 binding strongly depended on the position of the G3 module in the sequence of the constructs. Further improvement of these constructs for biomedical applications requires deciphering the molecular mechanism responsible for this effect. Here, we investigate the structural and dynamic aspects of ABD–G3 and G3–ABD chimeras using NMR spectroscopy and molecular modeling. Based on biophysical data, we come to the conclusion that extensive inter-domain contacts form in both constructs, although their binding interfaces and complex stability are somewhat different. Also, it is shown that the domain linker plays an important role—it limits the accessibility of the detected protein–protein binding sites, depending on the order of the domains in the chimeric molecules. These results create a solid structural basis for the rational design of new effective SP constructs targeting the signaling receptors in cells. [ABSTRACT FROM AUTHOR]

Background/objectives: The functional activity of a certain tumor determines the effectiveness of primary NK cells and NK-92 cell line-based cancer therapy; their therapeutic effectiveness against different tumors can vary. This work provides a direct simultaneous comparison of the cytotoxic effects of in vitro-activated peripheral NK (pNK) cells and NK-92 cells in spheroid models of BT-474, MCF7 and SKOV-3 carcinomas and uncovers the reasons for the differential effectiveness of NK cells against tumors. Methods: Tumor spheroids of similar size and shape, obtained from agarose molds, were incubated with NK-92 or pNK cells for 24 h. Tumor cell death was detected using flow cytometry or confocal microscopy. Cytokine production, granzyme B levels and NK cell degranulation analyses were performed, along with pNK and target-cell phenotypic characterization. Results: While NK-92 and pNK cells lysed BT-474 spheroids with comparably low efficiency, pNK cells were more capable of eliminating MCF7 and SKOV-3 spheroids than NK-92 cells were. The results of the functional and phenotypic analyses strongly support the participation of the NKG2D-NKG2DL pathway in pNK cell activation induced by the most sensitive cytotoxic attack on SKOV-3 spheroids, whereas the CX3CR1-CX3CL1 axis appears to be involved in the pNK reaction against MCF-7 spheroids. Conclusions: We provide a new approach for the preliminary identification of the most promising NK cell receptors that can alter the effectiveness of cancer therapy depending on the specific tumor type. Using this approach, NK-92 cells or pNK subsets can be selected for further accumulation and/or genetic modification to improve specificity and reactivity. [ABSTRACT FROM AUTHOR]

The prevention of blindness from glaucoma requires multiple treatments to lower intraocular pressure. Here, human contact lenses are modified with highly porous metal‐organic frameworks with sustained release of brimonidine for prolonged glaucoma treatment. Various metal‐organic frameworks were screened for their attachment to lenses, loading with brimonidine, and drug‐release properties. Optimized therapeutic ocular lenses conjugated with MIL‐101(Cr) frameworks maintain optical transparency and power. Coating of lenses with MIL‐101(Cr) nanoparticles reduced brimonidine washout with tears and ensured a gradual and localized release of the drug into the eyeball through the cornea. The hybrid lenses provided a 4.5‐fold better decrease in eye pressure, compared by area under the curve (AUC) value to a commercially available brimonidine tartrate solution. Therapeutic lenses did not induce any notable eye irritation or corneal damage in vivo. The newly developed hybrid lenses are expected to provide a robust platform for the therapy and prevention of various ocular diseases. [ABSTRACT FROM AUTHOR]

Zirconium nitride (ZrN) nanoparticles (NPs) can offer appealing plasmonic properties for biomedical applications, but the synthesis of nontoxic, water-dispersible nanoformulations exhibiting plasmonic features in the biotransparency window presents a great challenge. Here, we report the synthesis, by methods of laser ablation, of small ZrN-based NPs, which are unique in combining photothermal heating and near-field enhancement in the transparency window. Depending on the synthesis environment, the formed ZrN-based NPs exhibit plasmonic absorption bands with maxima around 660–670 and 610–630 nm, which are largely red-shifted compared to what is expected from pure ZrN NPs. The observed shift is explained by the inclusion of zirconium oxide ZrOx (1 < x < 2) into NP composition and NP coating by naturally formed ZrOx. We then explored biophotonic applications of ZrN NPs. While pure NPs demonstrate their nontoxicity in vitro, their conjugation with anti-HER1 affibody ZHER1:1907 and subsequent photothermal heating with NIR-I laser cause 100% cancer cell death. In addition, profiting from the field enhancement, we demonstrate bioimaging functionality using a designed surface-enhanced Raman scattering probe based on an NP-conjugated azobenzene-CN-OH molecule as a Raman reporter. Combining a strong photothermal effect and the imaging option, laser-synthesized ZrN/ZrOx NPs promise a major advancement of theranostic modalities based on plasmonic nanomaterials. [ABSTRACT FROM AUTHOR]

Boron-enhanced proton therapy has recently appeared as a promising approach to increase the efficiency of proton therapy on tumor cells, and this modality can further be improved by the use of boron nanoparticles (B NPs) as local sensitizers to achieve enhanced and targeted therapeutic outcomes. However, the mechanisms of tumor cell elimination under boron-enhanced proton therapy still require clarification. Here, we explore possible molecular mechanisms responsible for the enhancement of therapeutic outcomes under boron NP-enhanced proton therapy. Spherical B NPs with a mode size of 25 nm were prepared by methods of pulsed laser ablation in water, followed by their coating by polyethylene glycol to improve their colloidal stability in buffers. Then, we assessed the efficiency of B NPs as sensitizers of cancer cell killing under irradiation with a 160.5 MeV proton beam. Our experiments showed that the combined effect of B NPs and proton irradiation induces an increased level of superoxide anion radical generation, which leads to the depolarization of mitochondria, a drop in their membrane mitochondrial potential, and the development of apoptosis. A comprehensive gene expression analysis (via RT-PCR) confirmed increased overexpression of 52 genes (out of 87 studied) involved in the cell redox status and oxidative stress, compared to 12 genes in the cells irradiated without B NPs. Other possible mechanisms responsible for the B NPs-induced radiosensitizing effect, including one related to the generation of alpha particles, are discussed. The obtained results give a better insight into the processes involved in the boron-induced enhancement of proton therapy and enable one to optimize parameters of proton therapy in order to maximize therapeutic outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: The presented article is devoted to the study of the safety, biodistribution and absorbed doses of a new radiopharmaceutical for diagnostics and evaluation of the treatment efficiency of tumors with hyperexpression of epithelial cell adhesion molecules by single-photon emission computed tomography. The results of the study showed the safety and tolerability of [99mTc]Tc(CO)3-(HE)3-Ec1 in patients with lung tumors. The absorbed dose values for [99mTc]Tc(CO)3-(HE)3-Ec1 SPECT are also within the acceptable limits. Also, [99mTc]Tc(CO)3-(HE)3-Ec1 SPECT showed primary diagnostic efficiency in visualizing tumors with EpCAM expression and regional metastases. The promising use of [99mTc]Tc(CO)3-(HE)3-Ec1 will allow the selection of patients for targeted immunotherapy of tumors and evaluation of the efficiency of such treatment. A high level of EpCAM overexpression in lung cancer makes this protein a promising target for targeted therapy. Radionuclide visualization of EpCAM expression would facilitate the selection of patients potentially benefiting from such treatment. Single-photon computed tomography (SPECT) using 99mTc-labeled engineered scaffold protein DARPin Ec1 has shown its effectiveness in imaging tumors with overexpression of EpCAM in preclinical studies, providing high contrast just a few hours after injection. This first-in-human study aimed to evaluate the safety and distribution of [99mTc]Tc(CO)3-(HE)3-Ec1 in patients with primary lung cancer. Twelve lung cancer patients were injected with 300.7 ± 103.2 MBq of [99mTc]Tc(CO)3-(HE)3-Ec1. Whole-body planar imaging (at 2, 4, 6 and 24 h after injection) and SPECT/CT of the lung (at 2, 4, and 6 h) were performed. The patients' vital signs and possible side effects were monitored up to 7 days after injection. The patients tolerated the injection of [99mTc]Tc(CO)3-(HE)3-Ec1 well, and their somatic condition remained normal during the entire follow-up period. There were no abnormalities in blood and urine tests after injection of [99mTc]Tc(CO)3-(HE)3-Ec1. The highest absorbed doses were in the kidneys, liver, pancreas, thyroid, gallbladder wall, and adrenals. There was also a relatively high accumulation of [99mTc]Tc(CO)3-(HE)3-Ec1 in the small and large intestines, pancreas and thyroid. According to the SPECT/CT, accumulation of [99mTc]Tc(CO)3-(HE)3-Ec1 in the lung tumor was found in all patients included in the study. Intensive accumulation of [99mTc]Tc(CO)3-(HE)3-Ec1 was also noted in regional metastases. [99mTc]Tc(CO)3-(HE)3-Ec1 can potentially be considered a diagnostic tracer for imaging EpCAM expression in lung cancer patients and other tumors with overexpression of EpCAM. [ABSTRACT FROM AUTHOR]

Biodegradable nanomaterials can significantly improve the safety profile of nanomedicine. Germanium nanoparticles (Ge NPs) with a safe biodegradation pathway are developed as efficient photothermal converters for biomedical applications. Ge NPs synthesized by femtosecond‐laser ablation in liquids rapidly dissolve in physiological‐like environment through the oxidation mechanism. The biodegradation of Ge nanoparticles is preserved in tumor cells in vitro and in normal tissues in mice with a half‐life as short as 3.5 days. Biocompatibility of Ge NPs is confirmed in vivo by hematological, biochemical, and histological analyses. Strong optical absorption of Ge in the near‐infrared spectral range enables photothermal treatment of engrafted tumors in vivo, following intravenous injection of Ge NPs. The photothermal therapy results in a 3.9‐fold reduction of the EMT6/P adenocarcinoma tumor growth with significant prolongation of the mice survival. Excellent mass‐extinction of Ge NPs (7.9 L g−1 cm−1 at 808 nm) enables photoacoustic imaging of bones and tumors, following intravenous and intratumoral administrations of the nanomaterial. As such, strongly absorbing near‐infrared‐light biodegradable Ge nanomaterial holds promise for advanced theranostics. [ABSTRACT FROM AUTHOR]

The development of nanozymes, artificial enzymes made from inorganic nanoparticles, is widely studied due to their affordability, durability, and strength. Gold nanoparticles (AuNPs) are employed to imitate peroxidase, glucose oxidase, lactate oxidase, superoxide dismutase, and catalase. The last one transforms intracellular hydrogen peroxide into molecular oxygen, whose deficiency is characteristic of the hypoxic tumor microenvironment. Thus, gold nanoparticles are thought to enhance the overall effectiveness of photodynamic therapy. However, the enzyme‐like activity of nanoparticles rapidly decreases in biological media, due to the aggregation and formation of the so‐called "protein corona". In this study, polymeric submicrocapsules loaded with AuNPs and a photodynamic dye are fabricated via Layer‐by‐Layer (LbL) assembly. The enhancement of photodynamic treatment efficacy by in situ production of oxygen by the catalase‐like effect of AuNPs is investigated. Polymeric capsules are thoroughly characterized in terms of physicochemical and catalytic properties, and as a proof of concept, their therapeutic potential is evaluated in vitro. Furthermore, encapsulated AuNPs shows significantly lower aggregation both upon storage and during the reaction course. The results shows that the polymer capsules, containing AuNPs and photodynamic dye, show significantly higher light‐induced cytotoxicity in comparison to the individual photodynamic dye, suggesting a synergistic effect between the formation of molecular oxygen by catalase‐like gold nanozymes and photodynamic action. [ABSTRACT FROM AUTHOR]

Nuclear medicine presents one of the most promising modalities for efficient non-invasive treatment of a variety of cancers, but the application of radionuclides in cancer therapy and diagnostics is severely limited by their nonspecific tissue accumulation and poor biocompatibility. Here, we explore the use of nanosized metal–organic frameworks (MOFs) as carriers of radionuclides to order to improve their delivery to tumour. To demonstrate the concept, we prepared polymer-coated MIL-101(Cr)-NH2 MOFs and conjugated them with clinically utilized radionuclide 188Re. The nanoparticles demonstrated high loading efficacy of radionuclide reaching specific activity of 49 MBq mg−1. Pharmacokinetics of loaded MOFs was investigated in mice bearing colon adenocarcinoma. The biological half-life of the radionuclide in blood was (20.9 ± 1.3) h, and nanoparticles enabled it to passively accumulate and retain in the tumour. The radionuclide delivery with MOFs led to a significant decrease of radioactivity uptake by the thyroid gland and stomach as compared with perrhenate salt injection, which is beneficial for reducing the side toxicity of nuclear therapy. The reported data on the functionalization and pharmacokinetics of MIL-101(Cr)-NH2 for radionuclide delivery unveils the promising potential of these MOFs for nuclear medicine. [ABSTRACT FROM AUTHOR]

Targeted medicine uses the distinctive features of cancer cells to find and destroy tumors. We present human epidermal growth factor receptor 2 (HER2)-targeted PLGA–chitosan nanoparticles for cancer therapy and visualization. Loading with two near-infrared (NIR) dyes provides imaging in the NIR transparency window and phototherapy triggered by 808 nm light. Nile Blue (NB) is a biocompatible solvatochromic NIR dye that serves as an imaging agent. Laser irradiation of IR-780 dye leads to a temperature rise and the generation of reactive oxygen species (ROS). Resonance energy transfer between two dyes allows visualization of tumors in a wide range of visible and IR wavelengths. The combination of two NIR dyes enables the use of nanoparticles for diagnostics only or theranostics. Modification of poly(lactic-co-glycolic acid) (PLGA)–chitosan nanoparticles with trastuzumab provides an efficient nanoparticle uptake by tumor cells and promotes more than sixfold specificity towards HER2-positive cells, leading to a synergistic anticancer effect. We demonstrate optical imaging of the HER2-positive mouse mammary tumor and tumor-specific accumulation of PLGA–IR-780–NB nanoparticles in vivo after intravenous administration. We managed to achieve almost complete suppression of the proliferative activity of cells in vitro by irradiation with an 808 nm laser with a power of 0.27 W for 1 min at a concentration at which nanoparticles are nontoxic to cells in the dark. [ABSTRACT FROM AUTHOR]

Boron neutron capture therapy (BNCT) is one of the most appealing radiotherapy modalities, whose localization can be further improved by the employment of boron-containing nanoformulations, but the fabrication of biologically friendly, water-dispersible nanoparticles (NPs) with high boron content and favorable physicochemical characteristics still presents a great challenge. Here, we explore the use of elemental boron (B) NPs (BNPs) fabricated using the methods of pulsed laser ablation in liquids as sensitizers of BNCT. Depending on the conditions of laser-ablative synthesis, the used NPs were amorphous (a-BNPs) or partially crystallized (pc-BNPs) with a mean size of 20 nm or 50 nm, respectively. Both types of BNPs were functionalized with polyethylene glycol polymer to improve colloidal stability and biocompatibility. The NPs did not initiate any toxicity effects up to concentrations of 500 µg/mL, based on the results of MTT and clonogenic assay tests. The cells with BNPs incubated at a 10B concentration of 40 µg/mL were then irradiated with a thermal neutron beam for 30 min. We found that the presence of BNPs led to a radical enhancement in cancer cell death, namely a drop in colony forming capacity of SW-620 cells down to 12.6% and 1.6% for a-BNPs and pc-BNPs, respectively, while the relevant colony-forming capacity for U87 cells dropped down to 17%. The effect of cell irradiation by neutron beam uniquely was negligible under these conditions. Finally, to estimate the dose and regimes of irradiation for future BNCT in vivo tests, we studied the biodistribution of boron under intratumoral administration of BNPs in immunodeficient SCID mice and recorded excellent retention of boron in tumors. The obtained data unambiguously evidenced the effect of a neutron therapy enhancement, which can be attributed to efficient BNP-mediated generation of α-particles. [ABSTRACT FROM AUTHOR]