Magnetically Driven Self-Degrading Zinc-Containing Cystine Microrobots for Treatment of Prostate Cancer

Prostate cancer is the most commonly diagnosed tumor disease in men, and its treatment is still a big challenge in standard oncology therapy. Magnetically actuated microrobots represent the most promising technology in modern nanomedicine, offering the advantage of wireless guidance, effective cell penetration, and non-invasive actuation. Here, new biodegradable magnetically actuated zinc/cystine-based microrobots for in situ treatment of prostate cancer cells are reported. The microrobots are fabricated via metal-ion-mediated self-assembly of the amino acid cystine encapsulating superparamagnetic Fe₃ O₄ nanoparticles (NPs) during the synthesis, which allows their precise manipulation by a rotating magnetic field. Inside the cells, the typical enzymatic reducing environment favors the disassembly of the aminoacidic chemical structure due to the cleavage of cystine disulfide bonds and disruption of non-covalent interactions with the metal ions, as demonstrated by in vitro experiments with reduced nicotinamide adenine dinucleotide (NADH). In this way, the cystine microrobots served for site-specific delivery of Zn²⁺ ions responsible for tumor cell killing via a "Trojan horse effect". This work presents a new concept of cell internalization exploiting robotic systems' self-degradation, proposing a step forward in non-invasive cancer therapy.

Drugless nanoparticles tune-up an array of intertwined pathways contributing to immune checkpoint signaling and metabolic reprogramming in triple-negative breast cancer

Metabolic reprogramming 'Warburg effect' and immune checkpoint signaling are immunosuppressive hallmarks of triple-negative breast cancer (TNBC) contributing to the limited clinical applicability of immunotherapy. Biomaterials arise as novel tools for immunomodulation of the tumor microenvironment that can be used alongside conventional immunotherapeutics. Chitosan and lecithin are examples of versatile biomaterials with interesting immunomodulatory properties. In this study, we aimed at investigation of the role of carefully designed hybrid nanoparticles (NPs) on common mediators of both programmed death ligand 1 (PD-L1) expression and glycolytic metabolism. Hybrid lecithin-chitosan NPs were prepared and characterized. Their intracellular concentration, localization and effect on the viability of MDA-MB-231 cells were assessed. Glycolytic metabolism was quantified by measuring glucose consumption, adenosine triphosphate (ATP) generation, lactate production and extracellular acidification. Nitric oxide production was quantified using Greiss reagent. Gene expression of inducible nitric oxide synthase (iNOS), phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB or Akt), mammalian target of rapamycin (mTOR), hypoxia-inducible factor 1α(HIF-1α) and PD-L1 was quantified by quantitative reverse transcription polymerase chain reaction (q-RT-PCR). Chitosan, lecithin and the NPs-formulated forms have been shown to influence the 'Warburg effect' and immune checkpoint signaling of TNBC cells differently. The composition of the hybrid systems dictated their subcellular localization and hence the positive or negative impact on the immunosuppressive characteristics of TNBC cells. Carefully engineered hybrid lecithin-chitosan NPs could convert the immune-suppressive microenvironment of TNBC to an immune-active microenvironment via reduction of PD-L1 expression and reversal of the Warburg effect.

Optically Coupled PtOEP and DPA Molecules Encapsulated into PLGA-Nanoparticles for Cancer Bioimaging

Triplet-triplet annihilation upconversion (TTA-UC) nanoparticles (NPs) have emerged as imaging probes and therapeutic probes in recent years due to their excellent optical properties. In contrast to lanthanide ion-doped inorganic materials, highly efficient TTA-UC can be generated by low excitation power density, which makes it suitable for clinical applications. In the present study, we used biodegradable poly(lactic-co-glycolic acid) (PLGA)-NPs as a delivery vehicle for TTA-UC based on the heavy metal porphyrin Platinum(II) octaethylporphyrin (PtOEP) and the polycyclic aromatic hydrocarbon 9,10-diphenylanthracene (DPA) as a photosensitizer/emitter pair. TTA-UC-PLGA-NPs were successfully synthesized according to an oil-in-water emulsion and solvent evaporation method. After physicochemical characterization, UC-efficacy of TTA-UC-PLGA-NPs was assessed in vitro and ex vivo. TTA-UC could be detected in the tumour area 96 h after in vivo administration of TTA-UC-PLGA-NPs, confirming the integrity and suitability of PLGA-NPs as a TTA-UC in vivo delivery system. Thus, this study provides proof-of-concept that the advantageous properties of PLGA can be combined with the unique optical properties of TTA-UC for the development of advanced nanocarriers for simultaneous in vivo molecular imaging and drug delivery.

Polymer brush coated upconverting nanoparticles with improved colloidal stability and cellular labeling

Upconverting nanoparticles (UCNPs) possess great potential for biomedical application. UCNPs absorb and convert near-infrared (NIR) radiation in the biological imaging window to visible (Vis) and even ultraviolet (UV) radiation. NIR excitation offers reduced scattering and diminished autofluorescence in biological samples, whereas the emitted UV-Vis and NIR photons can be used for cancer treatment and imaging, respectively. However, UCNPs are usually synthesized in organic solvents and are not readily suitable for biomedical application due to the hydrophobic nature of their surface. Herein, we have removed the hydrophobic ligands from the synthesized UCNPs and coated the bare UCNPs with two custom-made hydrophilic polyelectrolytes (synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization method). Polymers containing different amounts of PEGylated and carboxylic groups were studied. Coating with both polymers increased the upconversion (UC) emission intensity and photoluminescence lifetime values of the UCNPs, which directly translates to more efficient cancer cell labeling nanoprobes. The polymer composition plays a crucial role in the modification of UCNPs, not only with respect to their colloidal stability, but also with respect to the cellular uptake. Colloidally unstable bare UCNPs aggregate in cell culture media and precipitate, rendering themselves unsuitable for any biomedical use. However, stabilization with polymers prevents UCNPs from aggregation, increases their uptake in cells, and improves the quality of cellular labeling. This investigation sheds light on the appropriate coating for UCNPs and provides relevant insights for the rational development of imaging and therapeutic tools.

An Iridium Complex as an AIE-active Photosensitizer for Image-guided Photodynamic Therapy

Image-guided photodynamic therapy (PDT) has received growing attention due to its non-invasiveness and precise controllability. However, the PDT efficiency of most photosensitizers are decreased in living system due to the aggregation-caused singlet oxygen (¹ O₂ ) generation decreasing. Herein, we present an Iridium (III) pyridylpyrrole complex (Ir-1) featuring of aggregation-induced emission (AIE) and ¹ O₂ generation characteristics for image-guided PDT of cancer. Ir-1 aqueous solution exhibits bright red phosphorescence peaked at 630 nm, large Stokes shift of 227 nm, and good ¹ O₂ generation ability. The ¹ O₂ generating rate of Ir-1 in EtOH/water mixture solution is 2.3 times higher than that of Rose Bengal. In vitro experimental results revealed that Ir-1 has better biocompatibility and higher phototoxicity compared with clinically used photosensitizers (Rose Bengal and Ce6), suggesting that Ir-1 can serve as a photosensitizer for image-guided PDT of cancer.

Genotoxicity and Gene Expression in the Rat Lung Tissue following Instillation and Inhalation of Different Variants of Amorphous Silica Nanomaterials (aSiO2 NM)

Several reports on amorphous silica nanomaterial (aSiO2 NM) toxicity have been questioning their safety. Herein, we investigated the in vivo pulmonary toxicity of four variants of aSiO2 NM: SiO2_15_Unmod, SiO2_15_Amino, SiO2_7 and SiO2_40. We focused on alterations in lung DNA and protein integrity, and gene expression following single intratracheal instillation in rats. Additionally, a short-term inhalation study (STIS) was carried out for SiO2_7, using TiO2_NM105 as a benchmark NM. In the instillation study, a significant but slight increase in oxidative DNA damage in rats exposed to the highest instilled dose (0.36 mg/rat) of SiO2_15_Amino was observed in the recovery (R) group. Exposure to SiO2_7 or SiO2_40 markedly increased oxidative DNA lesions in rat lung cells of the exposure (E) group at every tested dose. This damage seems to be repaired, since no changes compared to controls were observed in the R groups. In STIS, a significant increase in DNA strand breaks of the lung cells exposed to 0.5 mg/m3 of SiO2_7 or 50 mg/m3 of TiO2_NM105 was observed in both groups. The detected gene expression changes suggest that oxidative stress and/or inflammation pathways are likely implicated in the induction of (oxidative) DNA damage. Overall, all tested aSiO2 NM were not associated with marked in vivo toxicity following instillation or STIS. The genotoxicity findings for SiO2_7 from instillation and STIS are concordant; however, changes in STIS animals were more permanent/difficult to revert.

Ce6-C6-TPZ co-loaded albumin nanoparticles for synergistic combined PDT-chemotherapy of cancer

Photodynamic therapy (PDT), as an essential tumor treatment method, has received great attention; however, there are still some challenges such as hydrophobicity of most of the photosensitizers, safety of in vivo transport, and characteristics of oxygen consumption. Herein, we used albumin as the nanocarrier for the loading of Chlorin e6 (Ce6) photosensitizer. In the meantime, tirapazaming (TPZ) was co-loaded onto the nanocomposite, which could be activated by hypoxia caused by PDT for enhanced therapy. Considering the over irradiation problem, a strategy for measuring PDT degree by ratio fluorescence was utilized. The PDT monitoring design relies on ratio emissions of C6 (Coumarin 6) and Ce6 molecules since the red emission of Ce6 is dependent on the PDT capability. Based on the characterization of the albumin nanocomposites, we further explored the combined therapy effect at both the in vitro and in vivo levels and attained the corresponding results.

Potential Application of Upconverting Nanoparticles for Brain Photobiomodulation

Brain photobiomodulation (PBM) describes the use of visible to near-infrared light for modulation or stimulation of the central nervous system in both healthy individuals and diseased conditions. Although the transcranial approach to delivering light to the head is the most common technique to stimulate the brain, delivery of light to deeper structures in the brain is still a challenge. The science of nanoparticle engineering in combination with biophotonic excitation could provide a way to overcome this problem. Upconversion is an anti-Stokes process that is capable of transforming low energy photons that penetrate tissue well to higher energy photons with a greater biological effect, but poor tissue penetration. Wavelengths in the third optical window are optimal for light penetration into brain tissue, followed by windows II, IV, and I. The combination of trivalent lanthanide ions within a crystalline host provides a nanostructure that exhibits the upconversion phenomenon. Upconverting nanoparticles (UCNPs) have been successfully used in various medical fields. Their ability to cross the brain-blood barrier and their low toxicity make them a good candidate for application in brain disorders. It is possible that delivery of UCNPs to the brainstem or deeper parts of the cerebral tissue, followed by irradiation using light wavelengths with good tissue penetration properties, could allow more efficient PBM of the brain.

Membrane and nucleus targeting for highly sensitive cancer cell detection using pyrophosphate and alkaline phosphatase activity-mediated fluorescence switching of functionalized carbon dots

Fluorescence-switching of Cu²⁺–CD for specific membrane and nucleus targeting based on PPi and ALP activity in tumor cells.

Cytotoxicity studies of selected cadmium-based quantum dots on 2D vs. 3D cell cultures

In our work, the cytotoxicity of selected, cadmium-based quantum dots with various surface architectures was studied on 3D spheroids.