Context-Responsive Nanoparticle Derived from Synthetic Zwitterionic Ionizable Phospholipids in Targeted CRISPR/Cas9 Therapy for Basal-like Breast Cancer

The majority of triple negative breast cancers (TNBCs) are basal-like breast cancers (BLBCs), which tend to be more aggressive, proliferate rapidly, and have poor clinical outcomes. A key prognostic biomarker and regulator of BLBC is the Forkhead box C1 (FOXC1) transcription factor. However, because of its functional placement inside the cell nucleus and its structural similarity with other related proteins, targeting FOXC1 for therapeutic benefit, particularly for BLBC, continues to be difficult. We envision targeted nonviral delivery of CRISPR/Cas9 plasmid toward the efficacious knockdown of FOXC1. Keeping in mind the challenges associated with the use of CRISPR/Cas9 in vivo, including off-targeting modifications, and effective release of the cargo, a nanoparticle with context responsive properties can be designed for efficient targeted delivery of CRISPR/Cas9 plasmid. Consequently, we have designed, synthesized, and characterized a zwitterionic amino phospholipid-derived transfecting nanoparticle for delivery of CRISPR/Cas9. The construct becomes positively charged only at low pH, which encourages membrane instability and makes it easier for nanoparticles to exit endosomes. This has enabled effective in vitro and in vivo downregulation of protein expression and genome editing. Following this, we have used EpCAM aptamer to make the system targeted toward BLBC cell lines and to reduce its off-target toxicity. The in vivo efficacy, biodistribution, preliminary pharmacokinetics, and biosafety of the optimized targeted CRISPR nanoplatform is then validated in a rodent xenograft model. Overall, we have attempted to knockout the proto-oncogenic FOXC1 expression in BLBC cases by efficient delivery of CRISPR effectors via a context-responsive nanoparticle delivery system derived from a designer lipid derivative. We believe that the nonviral approach for in vitro and in vivo delivery of CRISPR/Cas9 targeted toward FOXC1, studied herein, will greatly emphasize the therapeutic regimen for BLBC.

Practical and Scalable Two-Step Process for 6-(2-Fluoro-4-nitrophenyl)-2-oxa-6-azaspiro[3.3]heptane: A Key Intermediate of the Potent Antibiotic Drug Candidate TBI-223

A low-cost, protecting group-free route to 6-(2-fluoro-4-nitrophenyl)-2-oxa-6-azaspiro[3.3]heptane (1), the starting material for the in-development tuberculosis treatment TBI-223, is described. The key bond forming step in this route is the creation of the azetidine ring through a hydroxide-facilitated alkylation of 2-fluoro-4-nitroaniline (2) with 3,3-bis(bromomethyl)oxetane (BBMO, 3). After optimization, this ring formation reaction was demonstrated at 100 g scale with isolated yield of 87% and final product purity of >99%. The alkylating agent 3 was synthesized using an optimized procedure that starts from tribromoneopentyl alcohol (TBNPA, 4), a commercially available flame retardant. Treatment of 4 with sodium hydroxide under Schotten-Baumann conditions closed the oxetane ring, and after distillation, 3 was recovered in 72% yield and >95% purity. This new approach to compound 1 avoids the previous drawbacks associated with the synthesis of 2-oxa-6-azaspiro[3,3]heptane (5), the major cost driver used in previous routes to TBI-223. The optimization and multigram scale-up results for this new route are reported herein.

Fluorescence Lifetimes of NIR-Emitting Molecules with Excited-State Intramolecular Proton Transfer

Molecular probes based on the excited-state intramolecular proton-transfer (ESIPT) mechanism have emerged to be attractive candidates for various applications. Although the steady-state fluorescence mechanisms of these ESIPT-based probes have been reported extensively, less information is available about the fluorescence lifetime characteristics of newly developed NIR-emitting dyes. In this study, four NIR-emitting ESIPT dyes with different cyanine terminal groups were investigated to evaluate their fluorescence lifetime characteristics in a polar aprotic solvent such as CH₂Cl₂. By using the time-correlated single-photon counting (TCSPC) method, these ESIPT-based dyes revealed a two-component exponential decay (τ₁ and τ₂) in about 2-4 nanoseconds (ns). These two components could be related to the excited keto tautomers. With the aid of model compounds (5 and 6) and low-temperature fluorescence spectroscopy (at -189 ℃), this study identified the intramolecular charge transfer (ICT) as one of the major factors that influenced the τ values. The results of this study also revealed that both fluorescence lifetimes and fractional contributions of each component were significantly affected by the probe structures.

Plasmon Damping Rates in Coulomb-Coupled 2D Layers in a Heterostructure

The Coulomb excitations of charge density oscillation are calculated for a double-layer heterostructure. Specifically, we consider two-dimensional (2D) layers of silicene and graphene on a substrate. From the obtained surface response function, we calculated the plasmon dispersion relations, which demonstrate how the Coulomb interaction renormalizes the plasmon frequencies. Most importantly, we have conducted a thorough investigation of how the decay rates of the plasmons in these heterostructures are affected by the Coulomb coupling between different types of two-dimensional materials whose separations could be varied. A novel effect of nullification of the silicene band gap is noticed when graphene is introduced into the system. To utilize these effects for experimental and industrial purposes, graphical results for the different parameters are presented.

Delayed identification of massive pituitary apoplexy in pregnancy: A case report

Introduction and importance

Pituitary apoplexy is a very rare cause of sudden and severe headache with a neuro-ophthalmic deficit during pregnancy due to hemorrhage or infarction in the pituitary gland. Delayed identification can be life-threatening to both mother and baby.

Case presentation

A 40-year-old nulliparous female without any prior comorbidities in her 21 weeks of gestation presented with complaints of severe headache, vomiting, decreased vision, and altered sensorium for five days. On a low index of suspicion of pituitary apoplexy, she was managed in the line of impending eclampsia at a local center. On presentation to our center; the neurological deficit had progressed. CT head showed massive pituitary apoplexy with sellar and suprasellar extension. She underwent emergency right pterional craniotomy and resection of the tumor with hematoma evacuation but lost her life on her 2nd postoperative day.

Discussion

In the context of pregnancy, the diagnosis of pituitary apoplexy can get tricky and overlap with other common conditions such as preeclampsia or eclampsia. Magnetic resonance imaging (MRI) is the most sensitive investigation to confirm the diagnosis. Corticotropic deficiency with adrenal insufficiency is a potentially life-threatening disorder for both mother and the fetus if left untreated. The choice between conservative management and surgical approach depends on the neuro-ophthalmic signs, MRI findings, and gestational week.

Conclusion

Pituitary apoplexy should be a differential diagnosis of acute severe headache in pregnancy which when suspected should be investigated promptly. Early identification and multi-disciplinary team management are imperative for better outcomes.

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Pituitary apoplexy is a very rare condition in pregnancy.

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It presents with a sudden and severe headache with neuro-ophthalmic deficits due to hemorrhage in the pituitary gland.

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Delayed identification can have a grave outcome to both mother and baby.

Tailoring plasmon excitations in [Formula: see text] armchair nanoribbons

We have calculated and investigated the electronic states, dynamical polarization function and the plasmon excitations for [Formula: see text] nanoribbons with armchair-edge termination. The obtained plasmon dispersions are found to depend significantly on the number of atomic rows across the ribbon and the energy gap which is also determined by the nanoribbon geometry. The bandgap appears to have the strongest effect on both the plasmon dispersions and their Landau damping. We have determined the conditions when relative hopping parameter [Formula: see text] of an [Formula: see text] lattice has a strong effect on the plasmons which makes our material distinguished from graphene nanoribbons. Our results for the electronic and collective properties of [Formula: see text] nanoribbons are expected to find numerous applications in the development of the next-generation electronic, nano-optical and plasmonic devices.

NIR-emitting styryl dyes with large Stokes' shifts for imaging application: From cellular plasma membrane, mitochondria to Zebrafish neuromast

Near-infrared (NIR) emitting probes with very large Stokes' shifts play a crucial role in bioimaging applications, as the optical signals in this region exhibit high signal to background ratio and allow deeper tissue penetration. Herein we illustrate NIR-emitting probe 2 with very large Stokes' shifts (Δλ ≈ 260 - 272 nm) by integrating the excited-state intramolecular proton transfer (ESIPT) unit 2-(2'-hydroxyphenyl)benzoxazole (HBO) into a pyridinium derived cyanine. The ESIPT not only enhances the Stokes' shifts but also improves the quantum efficiency of the probe 2 (фfl = 0.27 - 0.40 in DCM). The application of 2 in live cells imaging reveals that compound 2 stains mitochondria in eukaryotic cells, normal human lungs fibroblast (NHLF), Zebrafish's neuromast hair cells, and support cells, and inner plasma membrane in prokaryotic cells, Escherichia coli (E. coli).

Synthesis and characterisation of N-gene targeted NIR-II fluorescent probe for selective localisation of SARS-CoV-2

Tracking the viral progression of SARS-CoV-2 in COVID-19 infected body tissues is an emerging need of the current pandemic. Imaging at near infrared second biological window (NIR-II) offers striking benefits over the other technologies to explore deep-tissue information. Here we design, synthesise and characterise a molecular probe that selectively targets the N-gene of SARS-CoV-2. Highly specific antisense oligonucleotides (ASOs) were conjugated to lead sulfide quantum dots using a UV-triggered thiol-ene click chemistry for the recognition of viral RNA. Our ex vivo imaging studies demonstrated that the probe exhibits aggregation induced NIR-II emission only in presence of SARS-CoV-2 RNA which can be attributed to the efficient hybridisation of the ASOs with their target RNA strands.

Unlocking the power of optical imaging in the second biological window: Structuring near-infrared II materials from organic molecules to nanoparticles

Biomedical imaging techniques play a crucial role in clinical diagnosis, surgical intervention, and prognosis. Fluorescence imaging in the second biological window (second near-infrared [NIR-II]; 1000-1700 nm) has attracted attention recently. NIR-II fluorescence imaging offers unique advantages in terms of reduced photon scattering, deep tissue penetration, high sensitivity, and many others. A host of materials, including small organic molecules, single-walled carbon nanotubes, polymeric and rare-earth-doped nanoparticles, have been explored as NIR-II emitting fluorescent probes. Efficient and viable approaches to design and develop fluorescence probes with tunable photophysical properties without compromising other key features are of paramount importance. Various chemical strategies are explored to increase the quantum yield of these imaging agents without compromising their spatiotemporal resolution, specificity, and tissue penetration capabilities. This review summarizes the strategies implemented to design and synthesize NIR-II emitting nanoparticles and small organic molecule-based fluorescent probes for applications in the biomedical field. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Progress in Tuning Emission of the Excited-State Intramolecular Proton Transfer (ESIPT)-Based Fluorescent Probes

In this review, we will summarize our recent progress in the design and application of novel organic sensors with emission in the near-infrared region (600-900 nm). By coupling different functional groups with excited-state intramolecular proton transfer (ESIPT) segments, new probes are developed to achieve a large Stokes shift, high sensitivity, and selectivity and to tune the emission toward the near-infrared region. The developed probes exhibit attractive optical properties for bioimaging and environmental science applications. In addition, we further discuss the photophysical properties of ESIPT dyes and how their fluorescence could be affected by structural/environmental factors, which should be considered during the development of robust ESIPT-based fluorescence probes. Their potential applications as imaging reagents are illustrated for intracellular membranes, mitochondria, lysosomes, and some biomolecules.

Magnetoplasmons for theα-T3model with filled Landau levels

Using theα-T3model, we carried out analytical and numerical calculations for the static and dynamic polarization functions in the presence of a perpendicular magnetic field. The model involves a parameterαwhich is the ratio of the hopping strength from an atom at the center of a honeycomb lattice to one of the atoms on the hexagon to the hopping strength around its rim. Our results were employed to determine the longitudinal dielectric function and the magnetoplasmon dispersion relation. The magnetic field splits the continuous valence, conduction and flat energy subband into discrete Landau levels which present significant effects on the polarization function and magnetoplasmon dispersion. This includes the fact that the energies of the Landau levels are valley dependent which leads to different behaviors of the polarization function as the hopping parameterα(orϕ= tan-1α) is reduced continuously toward zero. This essential critical behavior of the polarization function leads to a softening of a magnetoplasmon mode. We present results for a doped layer in the integer quantum Hall regime for fixed hopping parameterαand various magnetic fields as well as chosen magnetic field and differentαin the random phase approximation.

Synthesis of highly selective lysosomal markers by coupling 2-(2'-hydroxyphenyl)benzothiazole (HBT) with benzothiazolium cyanine (Cy): the impact of substituents on selectivity and optical properties

HBT-Cy 1 has been previously reported as a highly selective fluorescent probe for lysosome visualization in live cells. To further investigate the role of the structural components of HBT-Cy in lysosome selectivity, cyanine based fluorescent probe series (2-5) have been synthesized in good yields by connecting benzothiazolium cyanine (Cy) with 2-hydroxyphenylbenzothiazole (HBT) via a meta phenylene ring. Probes 2-5 exhibited exceptional photophysical properties including bright red-emission (λ_em≈ 630-650 nm), a large Stokes shift (Δλ > 130 nm) and high fluorescence quantum yields (φ_fl≈ 0.1-0.5). Probes 2, 3, and 5 exhibited exceptional selectivity towards cellular lysosomes in NHLF and MO3.13 cells. Our further study revealed that the phenyl benzothiazolium cyanine component (6) was the lysosome directing group in the HBT-Cy probe structure. The attachment of the hydroxyphenyl benzothiazole (HBT) component to the HBT-Cy probe structure has significantly improved its photophysical properties. Lysosome probes 2, 3 and 5 exhibited excellent biocompatibility, quick staining, bright red fluorescence, and wash-free application for live cell imaging. These probes further exhibited excellent characteristics for bioimaging experiments including a non-alkalinizing nature, high biocompatibility, high photostability and long-term imaging ability (>4 hours).

A NIR-emitting cyanine with large Stokes shifts for live cell imaging: large impact of the phenol group on emission

There are a limited number of near-infrared (NIR) emitting (λem = 700-900 nm) molecular probes for imaging applications. A NIR-emitting probe that exhibits emission at ∼800 nm with a large Stokes shift was synthesized and found to exhibit excellent selectivity towards mitochondria for live-cell imaging. The photophysical properties were attributed to an excited "cyanine structure" via intramolecular charge transfer (ICT) involving a phenol group.

An NIR emitting styryl dye with large Stokes shift to enable co-staining study on zebrafish neuromast hair cells

Hearing loss is a significant public health problem, and the "loss of sensory hair cells" is one of two leading causes in humans. Advanced imaging reagents are desirable for understanding the role of the surrounding support cells in the loss or regeneration of the hair cells. A styryl dye was found to exhibit NIR emission (λ_em ≈ 684 nm) with a very large Stokes shift (Δν ≈ 9190 cm^-1), due to the incorporation of excited state intramolecular proton transfer (ESIPT) mechanism. When used to stain live zebrafish embryos, the probe was found to exhibit good selectivity in targeting neuromasts, which are sensory organs on the surface of the fish's body. The finding was verified by direct comparison with the known neuromast-labeling reagent, 4-Di-2-ASP. In contrast to the existing styryl dyes that label neuromast hair cells, the new probe labeled both neuromast hair cells and the surrounding support cells, while giving discernable signals. The study thus illustrated a useful tool to aid the developmental study of two closely related cell types on the mechanosensory sensory organ of zebrafish, which is a powerful animal model for hearing loss research.

Conformational change due to intramolecular hydrophobic interaction leads to large blue-shifted emission from single molecular cage solutions

Intramolecular hydrophobic interaction in single metal–organic cage leads to the conformational change with a blue-shifted emission.

An NIR-emitting lysosome-targeting probe with large Stokes shift via coupling cyanine and excited-state intramolecular proton transfer

An NIR-emitting probe (λ_em ∼ 700 nm) with a large Stokes shift (Δλ ≈ 234 nm) is synthesized by using excited-state intramolecular proton transfer (ESIPT). The phenolic proton, which controls ESIPT, acts as a switch to give strong fluorescence at pH ≈ 5. The probe can selectively show lysosome organelles, therefore leading to a lysosome probe without exhibiting "an alkalinizing effect".