Highly Monodisperse, Size Tunable Glucosamine Conjugated CdSe Quantum Dots for Enhanced Cellular Uptake and Bioimaging

Semiconductor quantum dots (QDs) have been used in a variety of applications ranging from optoelectronics to biodiagnostic fields, primarily due to their size dependent fluorescent nature. CdSe nanocrystals (NCs) are generally synthesized via a hot injection method in an organic solvent. However, such NCs are insoluble in water and therefore preclude the direct usage toward biological systems. Thus, the preparation of more biocompatible water-soluble QDs with a high photoluminescent quantum yield (PLQY) is extremely important for imaging applications. Although previous literature has detailed on the synthesis of CdSe NCs in water, they suffer from poor size distribution and very low PLQY. The complex formation mechanism of CdSe NCs in an aqueous environment adversely affects the quality of NCs due to the presence of OH-, H+, and H2O moieties. Here in this article, we have presented the facile hydrothermal approach to obtain size tunable (2.9-5.1 nm), aqueous CdSe NCs with a narrow emission profile having ∼40 nm fwhm with 56% PLQY. Physicochemical properties of the synthesized water-soluble CdSe NCs were studied with the help of UV-vis, PL, XRD, FTIR, XPS, and HR-TEM analysis. Furthermore, the surface of the synthesized CdSe NCs was modified with d-glucosamine via EDC and NHS coupling to obtain a stable, biocompatible bioimaging probe. Furthermore, we demonstrated that their successful bioconjugation with glucosamine could facilitate effective internalization into the cellular matrix.

Mitochondrial phospholipid transport: Role of contact sites and lipid transport proteins

One of the major constituents of mitochondrial membranes is the phospholipids, which play a key role in maintaining the structure and the functions of the mitochondria. However, mitochondria do not synthesize most of the phospholipids in situ, necessitating the presence of phospholipid import pathways. Even for the phospholipids, which are synthesized within the inner mitochondrial membrane (IMM), the phospholipid precursors must be imported from outside the mitochondria. Therefore, the mitochondria heavily rely on the phospholipid transport pathways for its proper functioning. Since, mitochondria are not part of a vesicular trafficking network, the molecular mechanisms of how mitochondria receive its phospholipids remain a relevant question. One of the major ways that hydrophobic phospholipids can cross the aqueous barrier of inter or intraorganellar spaces is by apposing membranes, thereby decreasing the distance of transport, or by being sequestered by lipid transport proteins (LTPs). Therefore, with the discovery of LTPs and membrane contact sites (MCSs), we are beginning to understand the molecular mechanisms of phospholipid transport pathways in the mitochondria. In this review, we will present a brief overview of the recent findings on the molecular architecture and the importance of the MCSs, both the intraorganellar and interorganellar contact sites, in facilitating the mitochondrial phospholipid transport. In addition, we will also discuss the role of LTPs for trafficking phospholipids through the intermembrane space (IMS) of the mitochondria. Mechanistic insights into different phospholipid transport pathways of mitochondria could be exploited to vary the composition of membrane phospholipids and gain a better understanding of their precise role in membrane homeostasis and mitochondrial bioenergetics.

Radiolabeling of Platelets with 99mTc-HYNIC-Duramycin for In Vivo Imaging Studies

Following the in vivo biodistribution of platelets can contribute to a better understanding of their physiological and pathological roles, and nuclear imaging methods, such as single photon emission tomography (SPECT), provide an excellent method for that. SPECT imaging needs stable labeling of the platelets with a radioisotope. In this study, we report a new method to label platelets with 99mTc, the most frequently used isotope for SPECT in clinical applications. The proposed radiolabeling procedure uses a membrane-binding peptide, duramycin. Our results show that duramycin does not cause significant platelet activation, and radiolabeling can be carried out with a procedure utilizing a simple labeling step followed by a size-exclusion chromatography-based purification step. The in vivo application of the radiolabeled human platelets in mice yielded quantitative biodistribution images of the spleen and liver and no accumulation in the lungs. The performed small-animal SPECT/CT in vivo imaging investigations revealed good in vivo stability of the labeling, which paves the way for further applications of 99mTc-labeled-Duramycin in platelet imaging.

Correction: Synthesis and preclinical application of a Prussian blue-based dual fluorescent and magnetic contrast agent (CA)

[This corrects the article DOI: 10.1371/journal.pone.0264554.].

Molecular imaging of bacterial outer membrane vesicles based on bacterial surface display

The important roles of bacterial outer membrane vesicles (OMVs) in various diseases and their emergence as a promising platform for vaccine development and targeted drug delivery necessitates the development of imaging techniques suitable for quantifying their biodistribution with high precision. To address this requirement, we aimed to develop an OMV specific radiolabeling technique for positron emission tomography (PET). A novel bacterial strain (E. coli BL21(DE3) ΔnlpI, ΔlpxM) was created for efficient OMV production, and OMVs were characterized using various methods. SpyCatcher was anchored to the OMV outer membrane using autotransporter-based surface display systems. Synthetic SpyTag-NODAGA conjugates were tested for OMV surface binding and 64Cu labeling efficiency. The final labeling protocol shows a radiochemical purity of 100% with a ~ 29% radiolabeling efficiency and excellent serum stability. The in vivo biodistribution of OMVs labeled with 64Cu was determined in mice using PET/MRI imaging which revealed that the biodistribution of radiolabeled OMVs in mice is characteristic of previously reported data with the highest organ uptakes corresponding to the liver and spleen 3, 6, and 12 h following intravenous administration. This novel method can serve as a basis for a general OMV radiolabeling scheme and could be used in vaccine- and drug-carrier development based on bioengineered OMVs.

Potential impact of various surface ligands on the cellular uptake and biodistribution characteristics of red, green, and blue emitting Cu nanoclusters

Surface functionalization has a prominent influence on tuning/manipulating the physicochemical properties of nanometer scaled materials. Ultrasmall sized nanoclusters with very few atoms have received enormous attention due to their bright fluorescence, biocompatibility, lower toxicity, good colloidal stability and strong photostability. These properties make them suitable for diagnostic applications. In this work, we intend to study the effect of surface functional ligands on their biodistribution both in vitro and in vivo organelle systems for bioimaging applications.

Surface Ligand Influences the Cu Nanoclusters as a Dual Sensing Optical Probe for Localized pH Environment and Fluoride Ion

Functional metal nanomaterials, especially in the nanocluster (NC) size regime, with strong fluorescence, aqueous colloidal stability, and low toxicity, necessitate their application potential in biology and environmental science. Here, we successfully report a simple cost-effective method for red-/green-color-emitting protein/amino-acid-mediated Cu NCs in an aqueous medium. As-synthesized Cu NCs were characterized through UV-Vis absorption spectroscopy, fluorescence spectroscopy, time-resolved photoluminescence, dynamic light scattering, zeta potential, transmission electron microscopy and X-ray photoelectron spectroscopy. The optical properties of both Cu NCs responded linearly to the variation in pH in the neutral and alkaline ranges, and a robust pH reversible nature (between pH 7 and 11) was observed that could be extended to rapid, localized pH sensor development. However, a contrasting pH response nature between protein-Cu NCs and amino acid-Cu NCs was recorded. The alteration in protein secondary structure and strong binding nature of the surfactants were suggested to explain this behavior. Furthermore, we investigated their use as an efficient optical probe for fluoride ion detection. The limit of detection for protein-Cu NCs is 6.74 µM, whereas the limit of detection for amino acid-Cu NCs is 4.67 µM. Thus, it is anticipated that ultrasmall Cu NCs will exhibit promise in biological and environmental sensing applications.

Implicit satiety goals and food-related expectations predict portion size in older adults: Findings from the BAMMBE cohort

Portion size selection is an indicator of appetite and within younger adults, is predicted by factors such as expected satiety, liking and motivations to achieve an ideal sensation of fullness (i.e., implicit satiety goals). Currently, there is limited research available on the determinants of portion size selection within older adults. Therefore, the current study aimed to examine the relationship between individual differences in implicit satiety goals, food-related expectations, and portion size selection in older adults. Free-living older adult Singaporeans (N = 115; Nmales = 62; age: M = 66.21 years, SD = 4.78, range = 60-83 years) participated as part of the Brain, Ageing, Microbiome, Muscle, Bone, and Exercise Study (BAMMBE). Participants completed questionnaires on their subjective requirements for experiencing different states of satiety and food-related expectations (i.e., liking, how filling) as well as a computerised portion size selection task. Using a multiple regression, we found that goals to feel comfortably full (B = 3.08, SE = 1.04, t = 2.96, p = .004) and to stop hunger (B = -2.25, SE = 0.82, t = -2.75, p = .007) significantly predicted larger portion size selection (R2 = 0.24, F(4,87) = 6.74, p < .001). Larger portion sizes (R2 = 0.53, F(5,90) = 20.58, p < .001) were also predicted by greater expected satiety (B = 0.47, SE = 0.09, t = 5.15, p < .001) and lower perceptions of how filling foods are (B = -2.92, SE = 0.77, t = -3.79, p < .001) but not liking (B = -0.09, SE = 0.91, t = -0.10, p = .925) or frequency (B = -18.42, SE = 16.91, t = -1.09, p = .279) of consumption of target foods. Comparing our findings to results of studies conducted with younger adults suggests the influence of factors such as satiety related goals on portion size selection may change with ageing while the influence of other factors (e.g., expected satiety/fullness delivered by foods) may remain consistent. These findings may inform future strategies to increase/decrease portion size accordingly to ensure older adults maintain an appropriate healthy weight.

Biomedical and Textile Applications of Alternanthera sessilis Leaf Extract Mediated Synthesis of Colloidal Silver Nanoparticle

The aqueous extract of Alternanthera sessilis (As) acts as the precursors for the quick reduction of silver ions, which leads to the formation of silver nanoparticles. In the agar, well diffusion method of the Klebsiella pneumoniae shows the minimal inhibitory concentration of 12 mm against A. sessilis mediated silver nanoparticles (As-AgNPs) at 60 µg/mL concentration. Fabric treated with novel AS-AgNPs is tested against the K. pneumoniae and shows an inhibitory action of 12 mm with mixed cotton that determines the antimicrobial efficacy of the fabrics. Uv- visible spectrophotometer was performed, showing a surface plasmon resonance peak at 450 nm cm^-1. FTIR shows the vibration and the infrared radiation at a specific wavelength of 500-4000 cm^-1. The HR-TEM analysis showed the presence of black-white crystalline, spherical-shaped As-AgNPs embedded on the fabrics range of 15 nm-40 nm. In the scanning electron microscope, the presence of small ball-shaped As-AgNPs embedded on the fabrics at a voltage of 30 KV was found with a magnification of 578X. EDAX was performed in which the nanoparticles show a peak of 2.6-3.9 KeV, and it also reveals the presence of the composition, distribution, and elemental mapping of the nanoparticles. The cytotoxic activity of synthesized nanosilver was carried out against L929 cell lines, which show cell viability at a concentration of 2.5 µg mL^-1. Cell proliferation assay shows no cytotoxicity against L929 cell lines for 24 h. In this study, the green synthesis of silver nanoparticles from A. sessilis appears to be a cheap, eco-friendly, and alternative approach for curing infectious ulcers on the floor of the stratum corneum. Nanotechnology conjoined with herbal therapeutics provides a promising solution for wound management.

Synthesis and preclinical application of a Prussian blue-based dual fluorescent and magnetic contrast agent (CA)

The aim of this study was to develop and characterize a Prussian Blue based biocompatible and chemically stable T1 magnetic resonance imaging (MRI) contrast agent with near infrared (NIR) optical contrast for preclinical application. The physical properties of the Prussian blue nanoparticles (PBNPs) (iron (II); iron (III);octadecacyanide) were characterized with dynamic light scattering (DLS), zeta potential measurement, atomic force microscopy (AFM), and transmission electron microscopy (TEM). In vitro contrast enhancement properties of PBNPs were determined by MRI. In vivo T1-weighted contrast of the prepared PBNPs was investigated by MRI and optical imaging modality after intravenous administration into NMRI-Foxn1 nu/nu mice. The biodistribution studies showed the presence of PBNPs predominantly in the cardiovascular system. Briefly, in this paper we show a novel approach for the synthesis of PBNPs with enhanced iron content for T1 MRI contrast. This newly synthetized PBNP platform could lead to a new diagnostic agent, replacing the currently used Gadolinium based substances.

A Brief Introduction to Magnetoencephalography (MEG) and Its Clinical Applications

Magnetoencephalography (MEG) plays a pivotal role in the diagnosis of brain disorders. In this review, we have investigated potential MEG applications for analysing brain disorders. The signal-to-noise ratio (SNRMEG = 2.2 db, SNREEG < 1 db) and spatial resolution (SRMEG = 2−3 mm, SREEG = 7−10 mm) is higher for MEG than EEG, thus MEG potentially facilitates accurate monitoring of cortical activity. We found that the direct electrophysiological MEG signals reflected the physiological status of neurological disorders and play a vital role in disease diagnosis. Single-channel connectivity, as well as brain network analysis, using MEG data acquired during resting state and a given task has been used for the diagnosis of neurological disorders such as epilepsy, Alzheimer’s, Parkinsonism, autism, and schizophrenia. The workflow of MEG and its potential applications in the diagnosis of disease and therapeutic planning are also discussed. We forecast that computer-aided algorithms will play a prominent role in the diagnosis and prediction of neurological diseases in the future. The outcome of this narrative review will aid researchers to utilise MEG in diagnostics.

Four Dietary Patterns Observed Within an Elderly Asian Cohort

Objectives

Dietary indices are largely established in American and European populations to measure diet quality based on the predominant food type and quantity consumed in those countries. However, applying these dietary indices to Asian or South Asian populations is complicated by diverse region-specific eating patterns, cultures and food availability. A challenge exists to identify a more relevant dietary index that agrees with distinct dietary patterns within the multi-ethnic Singapore context and what measures of dietary quality are appropriate for the unique food availability. This study aimed to characterise dietary patterns and quality in older Singapore individuals.

Methods

Daily energy, food and nutrient intakes were estimated from 2 sets of 3-day food records (IRB-2018–01-011)using an in-house and public databases (Singapore Food and Nutrient Composition database, and Phenol-Explorer). Diet composition was categorised into 33 food groups and hierarchical clustering (Ward's method) was performed to characterise habitual dietary patterns based on energy intake. Adherence to Healthy Eating Index (HEI) and MEDI-LITE score were assessed. Differences in energy, food groups and nutrients were analysed using Kruskal-Wallis test and permutational multivariate analysis of variance.

Results

We observed four distinct dietary patterns- i) noodle/rice-based diet, ii) highly refined diet, iii) energy-dense diet and iv) high-fibre diet consumed by 21%, 27%, 36% and 16% of the cohort, respectively (66 ± 5 years old, 1640–1874 kcal/day). Two patterns comprised high intakes of refined foods (i.e., white rice, bread, noodles), differed substantially from Western or Mediterranean diets and were characterised by higher visceral trunk fat. In contrast, the high-fibre pattern had favourable cardiometabolic risk markers and reduced body fat. These dietary patterns did not fit with HEI and MEDI-LITE score, considering the preference for rice, noodles and spices in Asian diets, and reduced preference for cereals, olive oil and red wine (emphasised in MEDI-LITE score).

Conclusions

Studying populations exposed to regionally diverse food components challenge the relevance of applying previously established diet indices.

Funding Sources

This project was funded by LKC, CONIC and ARISE, NTU, and NTU-CSIRO Precision Health and Technologies Seed Fund.

Diet-Associated Variability in the Elderly Gut Microbiome

Objectives

The gut microbiome adapts to diet variations, which contribute to interindividual variability in human host metabolism and environmental factors. Microbe-diet studies have largely focused on specific diets (e.g., high-fat Western, Mediterranean-style) in American and European populations, with limited studies on compositionally-different diets in Asian populations. This study aimed to understand how diet composition modulates the gut microbiome in a Singapore multi-ethnic population.

Methods

We performed metagenomic sequencing of faecal samples from 118 healthy individuals (66 ± 5 years old), and estimated their food and nutrient intakes from 3-day food records (IRB-2018–01-011). Multivariate associations between microbial composition (species) and functional potentials (pathways, enzymes) with diet variables were analysed using linear mixed models with Benjamin-Hochberg correction, and adjusted for age, sex, BMI, physical activity, energy intake and medications. Permutational multivariate analysis of variance, based on Bray-Curtis dissimilarity metric, was applied to quantify variance within the microbiome that is explained by diet variables.

Results

We found gut microbes (5 phyla, >100 species) significantly associated with one of four observed dietary patterns (P < 0.05), various food groups and nutrients (q < 0.1). The microbiome was driven by intake and diversity of plant-based foods. Parabacteroides and Blautia species, and microbial metabolism of energy, carbohydrate and glycan were associated with increased intakes of white rice and noodles. Prevotella species were associated with increased intakes of legumes, wholegrains and plant protein. Lachnospira, Clostridiumand Fournierella species, and microbial lipid metabolism were associated with energy-dense diet. Lastly, Firmicutes, Eubacterium, Ruminococcus and Roseburia species as well as microbial regulation of amino acid metabolism were associated with high-fibre diet.

Conclusions

This study provides new insights into gut microbial variations by distinct Asian dietary composition, supporting the feasibility of intervening habitual diets to reshape the gut microbiome for better health.

Funding Sources

This project was funded by LKC, CONIC and ARISE, NTU, and NTU-CSIRO Precision Health and Technologies Seed Fund.

3D culturing of human pluripotent stem cells-derived endothelial cells for vascular regeneration

Rationale: Human induced pluripotent stem cell-derived endothelial cells can be candidates for engineering therapeutic vascular grafts. Methods: Here, we studied the role of three-dimensional culture on their characteristics and function both in vitro and in vivo. Results: We found that differentiated hPSC-EC can re-populate decellularized biomatrices; they remain viable, undergo maturation and arterial/venous specification. Human PSC-EC develop antifibrotic, vasoactive and anti-inflammatory properties during recellularization. In vivo, a robust increase in perfusion was detected at the engraftment sites after subcutaneous implantation of an hPSC-EC-laden hydrogel in rats. Histology confirmed survival and formation of capillary-like structures, suggesting the incorporation of hPSC-EC into host microvasculature. In a canine model, hiPSC-EC-seeded onto decellularised vascular segments were functional as aortic grafts. Similarly, we showed the retention and maturation of hiPSC-EC and dynamic remodelling of the vessel wall with good maintenance of vascular patency. Conclusions: A combination of hPSC-EC and biomatrices may be a promising approach to repair ischemic tissues.

Structural Characterization, Antimicrobial, Antibiofilm, Antioxidant, Anticancer and Acute Toxicity Properties of N-(2-hydroxyphenyl)-2-phenazinamine From Nocardiopsis exhalans (KP149558)

The present study aimed to isolate and identify potential drugs from marine actinomycete Nocardiopsis exhalans and screen them for biomedical applications. The cell-free culture of N. exhalans was extracted with ethyl acetate and the solvent extract showed six fractions in thin-layer chromatography. The fractions were subjected to column chromatography for purification and evaluated for activity against human clinical pathogens. Fraction 4 showed significant activity and was identified as N-(2-hydroxyphenyl)-2-phenazinamine (NHP) using spectral analyses. Further, NHP showed excellent biofilm inhibitory activity against human clinical pathogens Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The in vitro antioxidant activity confirmed that NHP is scavenging the oxidative stress-enhancing molecules. The anti-proliferative activity of NHP against human breast cancer cells showed significant activity at 300 µg/ml and less cytotoxic activity against normal cells. Additionally, the toxicity assessment against zebrafish revealed that NHP does not cause any toxicity in the important organs. The results highlight N. exhalans as a promising candidate for the development of antibiotics with potential therapeutic applications.

Plasmonic random laser enabled artefact-free wide-field fluorescence bioimaging: uncovering finer cellular features

Narrow bandwidth, high brightness, and spectral tunability are the unique properties of lasers that make them extremely desirable for fluorescence imaging applications. However, due to the high spatial coherence, conventional lasers are often incompatible for wide-field fluorescence imaging. The presence of parasitic artefacts under coherent illumination causes uneven excitation of fluorophores, which has a critical impact on the reliability, resolution, and efficiency of fluorescence imaging. Here, we demonstrate artefact-free wide-field fluorescence imaging with a bright and low threshold silver nanorod based plasmonic random laser, offering the capability to image finer cellular features with sub-micrometer resolution even in highly diffusive biological samples. A spatial resolution of 454 nm and up to 23% enhancement in the image contrast in comparison to conventional laser illumination are attained. Based on the results presented in this paper, random lasers, with their laser-like properties and spatial incoherence are envisioned to be the next-generation sources for developing highly efficient wide-field fluorescence imaging systems having high spatial and temporal resolution for real-time, in vivo bioimaging.

Gadolinium and Polythiophene Functionalized Polyurea Polymer Dots as Fluoro-Magnetic Nanoprobes

A rapid and one-pot synthesis of poly 3-thiopheneacetic acid (PTAA) functionalized polyurea polymer dots (Pdots) using polyethyleneimine and isophorone diisocyanate is reported. The one-pot mini-emulsion polymerization technique yielded Pdots with an average diameter of ~20 nm. The size, shape, and concentration of the surface functional groups could be controlled by altering the synthesis parameters such as ultrasonication time, concentration of the surfactant, and crosslinking agent, and the types of isocyanates utilized for the synthesis. Colloidal properties of Pdots were characterized using dynamic light scattering and zeta potential measurements. The spherical geometry of Pdots was confirmed by scanning electron microscopy. The Pdots were post-functionalized by 1,4,7,10 tetraazacyclododecane-1,4,7,10-tetraacetic acid for chelating gadolinium nanoparticles (Gd³⁺) that provide magnetic properties to the Pdots. Thus, the synthesized Pdots possess fluorescent and magnetic properties, imparted by PTAA and Gd³⁺, respectively. Fluorescence spectroscopy and microscopy revealed that the synthesized dual-functional Gd³⁺-Pdots exhibited detectable fluorescent signals even at lower concentrations. Magnetic levitation experiments indicated that the Gd³⁺-Pdots could be easily manipulated via an external magnetic field. These findings illustrate that the dua- functional Gd³⁺-Pdots could be potentially utilized as fluorescent reporters that can be magnetically manipulated for bioimaging applications.

The Multifarious Applications of Copper Nanoclusters in Biosensing and Bioimaging and Their Translational Role in Early Disease Detection

Nanoclusters possess an ultrasmall size, amongst other favorable attributes, such as a high fluorescence and long-term colloidal stability, and consequently, they carry several advantages when applied in biological systems for use in diagnosis and therapy. Particularly, the early diagnosis of diseases may be facilitated by the right combination of bioimaging modalities and suitable probes. Amongst several metallic nanoclusters, copper nanoclusters (Cu NCs) present advantages over gold or silver NCs, owing to their several advantages, such as high yield, raw abundance, low cost, and presence as an important trace element in biological systems. Additionally, their usage in diagnostics and therapeutic modalities is emerging. As a result, the fluorescent properties of Cu NCs are exploited for use in optical imaging technology, which is the most commonly used research tool in the field of biomedicine. Optical imaging technology presents a myriad of advantages over other bioimaging technologies, which are discussed in this review, and has a promising future, particularly in early cancer diagnosis and imaging-guided treatment. Furthermore, we have consolidated, to the best of our knowledge, the recent trends and applications of copper nanoclusters (Cu NCs), a class of metal nanoclusters that have been gaining much traction as ideal bioimaging probes, in this review. The potential modes in which the Cu NCs are used for bioimaging purposes (e.g., as a fluorescence, magnetic resonance imaging (MRI), two-photon imaging probe) are firstly delineated, followed by their applications as biosensors and bioimaging probes, with a focus on disease detection.

Photocurrent-driven transient symmetry breaking in the Weyl semimetal TaAs

Symmetry plays a central role in conventional and topological phases of matter, making the ability to optically drive symmetry changes a critical step in developing future technologies that rely on such control. Topological materials, like topological semimetals, are particularly sensitive to a breaking or restoring of time-reversal and crystalline symmetries, which affect both bulk and surface electronic states. While previous studies have focused on controlling symmetry via coupling to the crystal lattice, we demonstrate here an all-electronic mechanism based on photocurrent generation. Using second harmonic generation spectroscopy as a sensitive probe of symmetry changes, we observe an ultrafast breaking of time-reversal and spatial symmetries following femtosecond optical excitation in the prototypical type-I Weyl semimetal TaAs. Our results show that optically driven photocurrents can be tailored to explicitly break electronic symmetry in a generic fashion, opening up the possibility of driving phase transitions between symmetry-protected states on ultrafast timescales.

Anticancer Potential of L-Histidine-Capped Silver Nanoparticles against Human Cervical Cancer Cells (SiHA)

This study reports the synthesis of silver nanoparticles using amino acid L-histidine as a reducing and capping agent as an eco-friendly approach. Fabricated L-histidine-capped silver nanoparticles (L-HAgNPs) were characterized by spectroscopic and microscopic studies. Spherical shaped L-HAgNPs were synthesized with a particle size of 47.43 ± 19.83 nm and zeta potential of -20.5 ± 0.95 mV. Results of the anticancer potential of L-HAgNPs showed antiproliferative effect against SiHa cells in a dose-dependent manner with an IC₅₀ value of 18.25 ± 0.36 µg/mL. Fluorescent microscopic analysis revealed L-HAgNPs induced reactive oxygen species (ROS) mediated mitochondrial dysfunction, leading to activation of apoptotic pathway and DNA damage eventually causing cell death. To conclude, L-HAgNPs can act as promising candidates for cervical cancer therapy.

Brain–Computer Interfacing Using Functional Near-Infrared Spectroscopy (fNIRS)

Functional Near-Infrared Spectroscopy (fNIRS) is a wearable optical spectroscopy system originally developed for continuous and non-invasive monitoring of brain function by measuring blood oxygen concentration. Recent advancements in brain–computer interfacing allow us to control the neuron function of the brain by combining it with fNIRS to regulate cognitive function. In this review manuscript, we provide information regarding current advancement in fNIRS and how it provides advantages in developing brain–computer interfacing to enable neuron function. We also briefly discuss about how we can use this technology for further applications.

Amyloid Beta42 (Aβ42) Peptide Functionalized Iron Oxide Nanoparticles for Specific Targeting of SH-SY5Y Neuroblastoma Cells

One of the most severe diseases threatening the ageing population is Alzheimer's disease (AD). Recent studies found that the cellular uptake of extracellular amyloid beta (Aβ) peptides can lead to a build-up of intracellular Aβ in certain neuronal cells, which consequently lead to the onset of AD pathogenesis. It is therefore hypothesized that the detection of cells that are involved in such Aβ uptake could facilitate the early diagnosis of AD. In this work, a magnetofluorescent nanoprobe was prepared conjugating dye-labeled Aβ42 peptides with iron oxide nanoparticles (IONPs). When incubated with SH-SY5Y cells, the cellular uptake of Aβ42-IONPs was enhanced, compared to that of bare IONPs. Further, by labelling SH-SY5Y and HCT-116 cells, it was found that the Aβ42-IONPs are selectively targeting the neuronal cells. This enhanced and specific neuronal targeting is attributed to the cellular uptake of extracellular amyloid by SH-SY5Y cells. In addition, the MR relaxivities of the Aβ42-IONPs are preserved after the peptides functionalization. The results suggest that the Aβ42 functionalized magnetofluorescent IONPs can be used as a bimodal probe to interrogate the cellular uptake of amyloid peptides.

Alzheimer's Disease: A Molecular View of β-Amyloid Induced Morbific Events

Amyloid-β (Aβ) is a dynamic peptide of Alzheimer’s disease (AD) which accelerates the disease progression. At the cell membrane and cell compartments, the amyloid precursor protein (APP) undergoes amyloidogenic cleavage by β- and γ-secretases and engenders the Aβ. In addition, externally produced Aβ gets inside the cells by receptors mediated internalization. An elevated amount of Aβ yields spontaneous aggregation which causes organelles impairment. Aβ stimulates the hyperphosphorylation of tau protein via acceleration by several kinases. Aβ travels to the mitochondria and interacts with its functional complexes, which impairs the mitochondrial function leading to the activation of apoptotic signaling cascade. Aβ disrupts the Ca²⁺ and protein homeostasis of the endoplasmic reticulum (ER) and Golgi complex (GC) that promotes the organelle stress and inhibits its stress recovery machinery such as unfolded protein response (UPR) and ER-associated degradation (ERAD). At lysosome, Aβ precedes autophagy dysfunction upon interacting with autophagy molecules. Interestingly, Aβ act as a transcription regulator as well as inhibits telomerase activity. Both Aβ and p-tau interaction with neuronal and glial receptors elevate the inflammatory molecules and persuade inflammation. Here, we have expounded the Aβ mediated events in the cells and its cosmopolitan role on neurodegeneration, and the current clinical status of anti-amyloid therapy.

Parkinson's Disease: A Nanotheranostic Approach Targeting Alpha-Synuclein Aggregation

Parkinson's disease (PD) is one of the most common neurodegenerative disorders that is implicated in aging populations. As numerous developed nations are experiencing progressively aging populations today, there is a heightened propensity for the occurrence of PD cases. Alpha-synuclein (α-syn) aggregation has been considered to be the pivotal mechanism leading to PD pathogenesis. Thus, early diagnostic and therapeutic strategies targeting the misfolded α-syn protein can potentially improve the prognosis of PD. With rapid advancements in nanotechnology in the last decade, effective solutions to various neurodegenerative and oncological diseases have been suggested. This review will explore the current innovations in nanotechnology that target the α-syn aggregation pathway, and reinstate the promise they hold as effective early diagnostic and therapeutic solutions to PD.

Positron emission tomographic imaging in drug discovery

Positron emission tomography (PET) is an extensively used nuclear functional imaging technique, especially for central nervous system (CNS) and oncological disorders. Currently, drug development is a lengthy and costly pursuit. Imaging with PET radiotracers could be an effective way to hasten drug discovery and advancement, because it facilitates the monitoring of key facets, such as receptor occupancy quantification, drug biodistribution, pharmacokinetic (PK) analyses, validation of target engagement, treatment monitoring, and measurement of neurotransmitter concentrations. These parameters demand careful analyses for the robust appraisal of newly formulated drugs during preclinical and clinical trials. In this review, we discuss the usage of PET imaging in radiopharmaceutical development; drug development approaches with PET imaging; and PET developments in oncological and cardiac drug discovery.

An In Vivo Study of a Rat Fluid-Percussion-Induced Traumatic Brain Injury Model with [11C]PBR28 and [18F]flumazenil PET Imaging

Traumatic brain injury (TBI) modelled by lateral fluid percussion-induction (LFPI) in rats is a widely used experimental rodent model to explore and understand the underlying cellular and molecular alterations in the brain caused by TBI in humans. Current improvements in imaging with positron emission tomography (PET) have made it possible to map certain features of TBI-induced cellular and molecular changes equally in humans and animals. The PET imaging technique is an apt supplement to nanotheranostic-based treatment alternatives that are emerging to tackle TBI. The present study aims to investigate whether the two radioligands, [¹¹C]PBR28 and [¹⁸F]flumazenil, are able to accurately quantify in vivo molecular-cellular changes in a rodent TBI-model for two different biochemical targets of the processes. In addition, it serves to observe any palpable variations associated with primary and secondary injury sites, and in the affected versus the contralateral hemispheres. As [¹¹C]PBR28 is a radioligand of the 18 kD translocator protein, the up-regulation of which is coupled to the level of neuroinflammation in the brain, and [¹⁸F]flumazenil is a radioligand for GABA_A-benzodiazepine receptors, whose level mirrors interneuronal activity and eventually cell death, the use of the two radioligands may reveal two critical features of TBI. An up-regulation in the [¹¹C]PBR28 uptake triggered by the LFP in the injured (right) hemisphere was noted on day 14, while the uptake of [¹⁸F]flumazenil was down-regulated on day 14. When comparing the left (contralateral) and right (LFPI) hemispheres, the differences between the two in neuroinflammation were obvious. Our results demonstrate a potential way to measure the molecular alterations in a rodent-based TBI model using PET imaging with [¹¹C]PBR28 and [¹⁸F]flumazenil. These radioligands are promising options that can be eventually used in exploring the complex in vivo pharmacokinetics and delivery mechanisms of nanoparticles in TBI treatment.

Neurophysiological Correlates of Cognition as Revealed by Virtual Reality: Delving the Brain with a Synergistic Approach

The synergy of perceptual psychology, technology, and neuroscience can be used to comprehend how virtual reality affects cognition of human brain. Numerous studies have used neuroimaging modalities to assess the cognitive state and response of the brain with various external stimulations. The virtual reality-based devices are well known to incur visual, auditory, and haptic induced perceptions. Neurophysiological recordings together with virtual stimulations can assist in correlating humans’ physiological perception with response in the environment designed virtually. The effective combination of these two has been utilized to study human behavior, spatial navigation performance, and spatial presence, to name a few. Moreover, virtual reality-based devices can be evaluated for the neurophysiological correlates of cognition through neurophysiological recordings. Challenges exist in the integration of real-time neuronal signals with virtual reality-based devices, and enhancing the experience together with real-time feedback and control through neuronal signals. This article provides an overview of neurophysiological correlates of cognition as revealed by virtual reality experience, together with a description of perception and virtual reality-based neuromodulation, various applications, and existing challenges in this field of research.

Altered striatal dopamine levels in Parkinson's disease VPS35 D620N mutant transgenic aged mice

Vacuolar protein sorting 35 (VPS35) is a major component of the retromer complex that mediates the retrograde transport of cargo proteins from endosomes to the trans-Golgi network. Mutations such as D620N in the VPS35 gene have been identified in patients with autosomal dominant Parkinson's disease (PD). However, it remains poorly understood whether and how VPS35 deficiency or mutation contributes to PD pathogenesis; specifically, the studies that have examined VPS35 thus far have differed in results and methodologies. We generated a VPS35 D620N mouse model using a Rosa26-based transgene expression platform to allow expression in a spatial manner, so as to better address these discrepancies. Here, aged (20-months-old) mice were first subjected to behavioral tests. Subsequently, DAB staining analysis of substantia nigra (SN) dopaminergic neurons with the marker for tyrosine hydroxylase (TH) was performed. Next, HPLC was used to determine dopamine levels, along with levels of its two metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in the striatum. Western blotting was also performed to study the levels of key proteins associated with PD. Lastly, autoradiography (ARG) evaluation of [³H]FE-PE2I binding to the striatal dopamine transporter DAT was carried out. We found that VPS35 D620N Tg mice displayed a significantly higher dopamine level than NTg counterparts. All results were then compared with that of current VPS35 studies to shed light on the disease pathogenesis. Our model allows future studies to explicitly control spatial expression of the transgene which would generate a more reliable PD phenotype.

Dealing with PET radiometabolites

Abstract

Positron emission tomography (PET) offers the study of biochemical, physiological, and pharmacological functions at a cellular and molecular level. The performance of a PET study mostly depends on the used radiotracer of interest. However, the development of a novel PET tracer is very difficult, as it is required to fulfill a lot of important criteria. PET radiotracers usually encounter different chemical modifications including redox reaction, hydrolysis, decarboxylation, and various conjugation processes within living organisms. Due to this biotransformation, different chemical entities are produced, and the amount of the parent radiotracer is declined. Consequently, the signal measured by the PET scanner indicates the entire amount of radioactivity deposited in the tissue; however, it does not offer any indication about the chemical disposition of the parent radiotracer itself. From a radiopharmaceutical perspective, it is necessary to quantify the parent radiotracer’s fraction present in the tissue. Hence, the identification of radiometabolites of the radiotracers is vital for PET imaging. There are mainly two reasons for the chemical identification of PET radiometabolites: firstly, to determine the amount of parent radiotracers in plasma, and secondly, to rule out (if a radiometabolite enters the brain) or correct any radiometabolite accumulation in peripheral tissue. Besides, radiometabolite formations of the tracer might be of concern for the PET study, as the radiometabolic products may display considerably contrasting distribution patterns inside the body when compared with the radiotracer itself. Therefore, necessary information is needed about these biochemical transformations to understand the distribution of radioactivity throughout the body. Various published review articles on PET radiometabolites mainly focus on the sample preparation techniques and recently available technology to improve the radiometabolite analysis process. This article essentially summarizes the chemical and structural identity of the radiometabolites of various radiotracers including [¹¹C]PBB3, [¹¹C]flumazenil, [¹⁸F]FEPE2I, [¹¹C]PBR28, [¹¹C]MADAM, and (+)[¹⁸F]flubatine. Besides, the importance of radiometabolite analysis in PET imaging is also briefly summarized. Moreover, this review also highlights how a slight chemical modification could reduce the formation of radiometabolites, which could interfere with the results of PET imaging.

Graphical abstract

3D Deep Learning on Medical Images: A Review

The rapid advancements in machine learning, graphics processing technologies and the availability of medical imaging data have led to a rapid increase in the use of deep learning models in the medical domain. This was exacerbated by the rapid advancements in convolutional neural network (CNN) based architectures, which were adopted by the medical imaging community to assist clinicians in disease diagnosis. Since the grand success of AlexNet in 2012, CNNs have been increasingly used in medical image analysis to improve the efficiency of human clinicians. In recent years, three-dimensional (3D) CNNs have been employed for the analysis of medical images. In this paper, we trace the history of how the 3D CNN was developed from its machine learning roots, we provide a brief mathematical description of 3D CNN and provide the preprocessing steps required for medical images before feeding them to 3D CNNs. We review the significant research in the field of 3D medical imaging analysis using 3D CNNs (and its variants) in different medical areas such as classification, segmentation, detection and localization. We conclude by discussing the challenges associated with the use of 3D CNNs in the medical imaging domain (and the use of deep learning models in general) and possible future trends in the field.

Fluorescent, Prussian Blue-Based Biocompatible Nanoparticle System for Multimodal Imaging Contrast

(1) Background. The main goal of this work was to develop a fluorescent dye-labelling technique for our previously described nanosized platform, citrate-coated Prussian blue (PB) nanoparticles (PBNPs). In addition, characteristics and stability of the PB nanoparticles labelled with fluorescent dyes were determined. (2) Methods. We adsorbed the fluorescent dyes Eosin Y and Rhodamine B and methylene blue (MB) to PB-nanoparticle systems. The physicochemical properties of these fluorescent dye-labeled PBNPs (iron(II);iron(III);octadecacyanide) were determined using atomic force microscopy, dynamic light scattering, zeta potential measurements, scanning- and transmission electron microscopy, X-ray diffraction, and Fourier-transformation infrared spectroscopy. A methylene-blue (MB) labelled, polyethylene-glycol stabilized PBNP platform was selected for further assessment of in vivo distribution and fluorescent imaging after intravenous administration in mice. (3) Results. The MB-labelled particles emitted a strong fluorescent signal at 662 nm. We found that the fluorescent light emission and steric stabilization made this PBNP-MB particle platform applicable for in vivo optical imaging. (4) Conclusion. We successfully produced a fluorescent and stable, Prussian blue-based nanosystem. The particles can be used as a platform for imaging contrast enhancement. In vivo stability and biodistribution studies revealed new aspects of the use of PBNPs.

Nanotechnology-Based Diagnostics and Therapy for Pathogen-Related Infections in the CNS

The central nervous system (CNS) encompasses the brain, spinal cord, and nerves, where both brain and spinal cord are safeguarded by the meninges. However, serious bacterial, viral, or fungal infection in the brain causes life-threatening diseases such as meningitis. Engineered nanostructures hold great promise for not only in the diagnosis but also for combating microbial drug resistance owing to their high surface area and innate antibacterial activity. We delineate several nanoparticle-based approaches to enhance the CNS delivery of drugs across the blood-brain barrier (BBB). While pathogens invade the CNS by phagocytosis or receptor (e.g., EphA2)-mediated transcytosis, most of the nanoparticles cross the BBB via receptor-mediated transcytosis (e.g., antibody, peptide, protein). We also provide our perspectives on the diagnostic pathways based on nanotechnology for the detection of pathogens in the brain, thereby opening up new therapeutic avenues.

The gut microbiota influences skeletal muscle mass and function in mice

The functional interactions between the gut microbiota and the host are important for host physiology, homeostasis, and sustained health. We compared the skeletal muscle of germ-free mice that lacked a gut microbiota to the skeletal muscle of pathogen-free mice that had a gut microbiota. Compared to pathogen-free mouse skeletal muscle, germ-free mouse skeletal muscle showed atrophy, decreased expression of insulin-like growth factor 1, and reduced transcription of genes associated with skeletal muscle growth and mitochondrial function. Nuclear magnetic resonance spectrometry analysis of skeletal muscle, liver, and serum from germ-free mice revealed multiple changes in the amounts of amino acids, including glycine and alanine, compared to pathogen-free mice. Germ-free mice also showed reduced serum choline, the precursor of acetylcholine, the key neurotransmitter that signals between muscle and nerve at neuromuscular junctions. Reduced expression of genes encoding Rapsyn and Lrp4, two proteins important for neuromuscular junction assembly and function, was also observed in skeletal muscle from germ-free mice compared to pathogen-free mice. Transplanting the gut microbiota from pathogen-free mice into germ-free mice resulted in an increase in skeletal muscle mass, a reduction in muscle atrophy markers, improved oxidative metabolic capacity of the muscle, and elevated expression of the neuromuscular junction assembly genes Rapsyn and Lrp4 Treating germ-free mice with short-chain fatty acids (microbial metabolites) partly reversed skeletal muscle impairments. Our results suggest a role for the gut microbiota in regulating skeletal muscle mass and function in mice.

Targeted pancreatic beta cell imaging for early diagnosis

Pancreatic beta cells are important in blood glucose level regulation. As type 1 and 2 diabetes are getting prevalent worldwide, we need to explore new methods for early detection of beta cell-related afflictions. Using bioimaging techniques to measure beta cell mass is crucial because a decrease in beta cell density is seen in diseases such as diabetes and thus can be a new way of diagnosis for such diseases. We also need to appraise beta cell purity in transplanted islets for type 1 diabetes patients. Sufficient amount of functional beta cells must also be determined before being transplanted to the patients. In this review, indirect imaging of beta cells will be discussed. This includes membrane protein on pancreatic beta cells whereby specific probes are designed for different imaging modalities mainly magnetic resonance imaging, positron emission tomography and fluorescence imaging. Direct imaging of insulin is also explored though probes synthesized for such function are relatively fewer. The path for successful pancreatic beta cell imaging is fraught with challenges like non-specific binding, lack of beta cell-restricted targets, the requirement of probes to cross multiple lipid layers to bind to intracellular insulin. Hence, there is an urgent need to develop new imaging techniques and innovative probing constructs in the entire imaging chain of bioengineering to provide early detection of beta cell-related pathology.

Au nano-urchins enabled localized surface plasmon resonance sensing of beta amyloid fibrillation

Early stage detection of neurodegenerative diseases such as Alzheimer's disease (AD) is of utmost importance, as it has become one of the leading causes of death of millions of people. The gradual intellectual decline in AD patients is an outcome of fibrillation of amyloid beta 1-42 (Aβ1-42) peptides in the brain. In this paper, we present localized surface plasmon resonance (LSPR) based sensing of Aβ1-42 fibrillation using Au nano-urchins. Strongly localized field confinement at the spiky nanostructures of nano-urchin surfaces enables them to detect very low concentrations of Aβ1-42. In addition, the LSPR peak of Au nano-urchins, which is very sensitive to ambient conditions, shows significant responses at different fibrillation stages of Aβ1-42. Reduction in LSPR peak intensity with an increase in the fibrillation is chosen as the sensing parameter here. This paper in this context provides LSPR based highly sensitive, label-free and real-time sensing of Aβ1-42 fibrillation that is highly advantageous compared to the existing techniques which require binding additives or fluorescent biomarkers.

Gadolinium-based bimodal probes to enhance T1-Weighted magnetic resonance/optical imaging

Gd³⁺-based contrast agents have been extensively used for signal enhancement of T₁-weighted magnetic resonance imaging (MRI) due to the large magnetic moment and long electron spin relaxation time of the paramagnetic Gd³⁺ ion. The key requisites for the development of Gd³⁺-based contrast agents are their relaxivities and stabilities which can be achieved by chemical modifications. These modifications include coordinating Gd³⁺ with a chelator such as diethylenetriamine pentaacetic acid (DTPA) or 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), encapsulating Gd³⁺ in nanoparticles, conjugation to biomacromolecules such as polymer micelles and liposomes, or non-covalent binding to plasma proteins. In order to have a coherent diagnostic and therapeutic approach and to understand diseases better, the combination of MRI and optical imaging (OI) techniques into one technique entity has been developed to overcome the conventional boundaries of either imaging modality used alone through bringing the excellent spatial resolution of MRI and high sensitivity of OI into full play. Novel MRI and OI bimodal probes have been extensively studied in this regard. This review is an attempt to shed some light on the bimodal imaging probes by summarizing all recent noteworthy publications involving Gd³⁺ containing MR-optical imaging probes. The several key elements such as novel synthetic strategy, high sensitivity, biocompatibility, and targeting of the probes are highlighted in the review. STATEMENT OF SIGNIFICANCE: The present article aims at giving an overview of the existing bimodal MRI and OI imaging probes. The review structured as a series of examples of paramagnetic Gd³⁺ ions, either as ions in the crystalline structure of inorganic materials or chelates for contrast enhancement in MRI, while they are used as optical imaging probes in different modes. The comprehensive review focusing on the synthetic strategies, characterizations and properties of these bimodal imaging probes will be helpful in a way to prepare related work.

Direct myosin-2 inhibition enhances cerebral perfusion resulting in functional improvement after ischemic stroke

Acute ischemic stroke treatment faces an unresolved obstacle as capillary reperfusion remains insufficient after thrombolysis and thrombectomy causing neuronal damage and poor prognosis. Hypoxia-induced capillary constriction is mediated by actomyosin contraction in precapillary smooth muscle cells (SMCs) therefore smooth muscle myosin-2 could be an ideal target with potentially high impact on reperfusion of capillaries. Methods: The myosin-2 inhibitor para-aminoblebbistatin (AmBleb) was tested on isolated human and rat arterioles to assess the effect of AmBleb on vasodilatation. Transient middle cerebral artery occlusion (MCAO) was performed on 38 male Wistar rats followed by local administration of AmBleb into the ischemic brain area. Development of brain edema and changes in cerebrovascular blood flow were assessed using MRI and SPECT. We also tested the neurological deficit scores and locomotor asymmetry of the animals for 3 weeks after the MCAO operation. Results: Our results demonstrate that AmBleb could achieve full relaxation of isolated cerebral arterioles. In living animals AmBleb recovered cerebral blood flow in 32 out of the 65 affected functional brain areas in MCAO operated rats, whereas only 8 out of the 67 affected areas were recovered in the control animals. Animals treated with AmBleb also showed significantly improved general and focal deficit scores in neurological functional tests and showed significantly ameliorated locomotor asymmetry. Conclusion: Direct inhibition of smooth muscle myosin by AmBleb in pre-capillary SMCs significantly contribute to the improvement of cerebral blood reperfusion and brain functions suggesting that smooth muscle myosin inhibition may have promising potential in stroke therapies as a follow-up treatment of physical or chemical removal of the occluding thrombus.

Codon usage of human hepatitis C virus clearance genes in relation to its expression

Hepatitis C virus (HCV) infection is among the leading causes of hepatocellular carcinoma and liver cirrhosis globally, with a high economic burden. The disease progression is well established, but less is known about the spontaneous HCV infection clearance. This study tries to establish the relationship between codon biasness and expression of HCV clearance candidate genes in normal and HCV infected liver tissues. A total of 112 coding sequences comprising 151 679 codons were subjected to the computation of codon indices, namely relative synonymous codon usage, an effective number of codon (Nc), frequency of optimal codon, codon adaptation index, codon bias index, and base compositions. Codon indices report of GC3s, GC12, hydropathicity, and aromaticity implicates both mutational and translational selection in the candidate gene set. This was further correlated with the differentially expressed genes among the selected genes using BioGPS. A significant correlation is observed between the gene expression of normal liver and cancerous liver tissues with codon bias (Nc). Gene expression is also correlated with relative codon bias values, indicating that CCL5, APOA2, CD28, IFITM1, and TNFSF4 genes have higher expression. These results are quite encouraging in selecting the high responsive genes in HCV clearance. However, there could be additional genes which could also orchestrate the clearance role with the above mentioned first line of defensive genes.

Bifunctional Fluorescent/Raman Nanoprobe for the Early Detection of Amyloid

One of the pathological hallmarks of Alzheimer's disease (AD) is the abnormal aggregation of amyloid beta (Aβ) peptides. Therefore the detection of Aβ peptides and imaging of amyloid plaques are considered as promising diagnostic methods for AD. Here we report a bifunctional nanoprobe prepared by conjugating gold nanoparticles (AuNPs) with Rose Bengal (RB) dye. RB is chosen due to its unique Raman fingerprints and affinity with Aβ peptides. After the conjugation, Raman signals of RB were significantly enhanced due to the surface-enhanced Raman scattering (SERS) effect. Upon binding with Aβ42 peptides, a spectrum change was detected, and the magnitude of the spectrum changes can be correlated with the concentration of target peptides. The peptide/probe interaction also induced a remarkable enhancement in the probes' fluorescence emission. This fluorescence enhancement was further utilized to image amyloid plaques in the brain slices from transgenic mice. In this study, the RB-AuNPs were used for both SERS-based detection of Aβ42 peptides and fluorescence-based imaging of amyloid plaques. Compared to monofunctional probes, the multifunctional probe is capable to provide more comprehensive pathophysiological information, and therefore, the implementation of such multifunctional amyloid probes is expected to help the investigation of amyloid aggregation and the early diagnosis of AD.

Optically Driven Collective Spin Excitations and Magnetization Dynamics in the Néel-type Skyrmion Host GaV_{4}S_{8}

GaV_{4}S_{8} is a multiferroic semiconductor hosting magnetic cycloid (Cyc) and Néel-type skyrmion lattice (SkL) phases with a broad region of thermal and magnetic stability. Here, we use time-resolved magneto-optical Kerr spectroscopy to show the coherent generation of collective spin excitations in the Cyc and SkL phases. Our micromagnetic simulations reveal that these are driven by an optically induced modulation of uniaxial anisotropy. Our results shed light on spin dynamics in anisotropic materials hosting skyrmions and pave a new pathway for the optical manipulation of their magnetic order.

Abstract P3-03-14: Clinical utility of one-step nucleic acid amplification (OSNA) in axillary surgery after neoadjuvant chemotherapy (NAC)

Introduction

NAC has been used for downsizing of the tumour in breast and axilla to allow more conservative surgery. In the NAC setting, intraoperative assessment of sentinel lymph node(s) (SLN) is still considered necessary1. Current awareness of the prognostic value for axillary nodal down-staging has renewed interest in analysis of SLN post-NAC.

In this study we want to examine the clinical utility of OSNA (based on CK19 mRNA detection) as a method of intra-operative analysis of SLN to assist real-time decision-making for axillary surgery post-NAC in early breast cancer (EBC).

Methods

Retrospective analysis of prospective data on 399 consecutive patients with EBC who received NAC followed by breast surgery with SLN biopsy (408 axillae) and assessment by OSNA, from September 2011 to January 2018 at the Royal Marsden Hospital (UK). OSNA readouts from the Sysmex RD-100i were collected separate to and blinded from clinico-pathological data. A negative or benign pre-treatment axillary ultrasound scan or indeterminate ultrasound with negative or benign axillary cytology/histology prior to NAC was considered cN0. Univariate analysis (significance at p&lt;0.05) was used to identify risk of recurrence. Patients had a median (mean) follow up of 32.5 (36) months.

Results

The median age at diagnosis was 49 years, median BMI 26, 41 EBC (10%) were screen-detected, 292 (72%) were grade 3 and the most frequent phenotype was receptor triple negative (n=132, 32%).

Of 408 axillae, 248 (60%) were initially cN0, of which 113 (46%) had a pathological complete response (pCR) in the breast. SLN in 54 (22%) cN0 patients were positive on OSNA, of which only 6 (9%) had further involved axillary nodes all 6 of which were ER+ Her2-.

The remaining 160 (40%) axillae were cN1 of which 87 (54%) had conversion to ypN0 including 55 (34%) with both ypT0ypN0.

Axillary lymphadenectomy (AL) was performed in 79 (19%) patients overall, of which n=22 (28%) were cN0 and 57 (72%) were cN1. Of these, 30 (53%) of the cN1 and 6 of 22 (45%) of cN0 had at least 1 additional positive AL node.

Overall 59 (14.4%) patients relapsed. A significantly worse rate of relapse was observed in cN1 compared to cN0 patients (37/159 (23.3%) versus 22/244 (9%), p&lt;0.001). Combined pCR of both breast and axilla (in cN1, n=54) was associated with a significantly reduced risk of relapse and death (p&lt;0.001) compared to those without pCR of either breast or axilla (n=62). Of the latter 18 (29%) relapsed (including 10 deaths).

The mean of both the single highest node tumour load (and total nodal tumour load), as measured by CK19mRNA copies/ul on OSNA, were significantly higher at 90,000 (98,300) for those who relapsed versus 23,100 (25,100) for those without relapse (p=0.027).

Conclusions

The OSNA assay is an accurate tool for axillary SLN analysis in patients after NAC and was helpful in intra-operative axillary management. OSNA reduces the need for a second surgery for AL in 20% of breast cancer patients with a positive-SLN after NAC and might offer additional prognostic value.

Reference

1. NCCN. National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology Breast Cancer.2016.Version 2.2016.

Citation Format: Muscara F, Christaki G, Richardson C, O'Connell R, Padmanabhan P, Warwick J, Lee Y, Smith I, Nerurkar A, Osin P, Krupa K, Rusby J, Roche N, Gui G, MacNeil F, Barry P. Clinical utility of one-step nucleic acid amplification (OSNA) in axillary surgery after neoadjuvant chemotherapy (NAC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-14.

PET-MR and SPECT-MR multimodality probes: Development and challenges

Positron emission tomography (PET)-magnetic resonance (MR) or single photon emission computed tomography (SPECT)-MR hybrid imaging is being used in daily clinical practice. Due to its advantages over stand-alone PET, SPECT or MR imaging, in many areas such as oncology, the demand for hybrid imaging techniques is increasing dramatically. The use of multimodal imaging probes or biomarkers in a single molecule or particle to characterize the imaging subjects such as disease tissues certainly provides us with more accurate diagnosis and promotes therapeutic accuracy. A limited number of multimodal imaging probes are being used in preclinical and potential clinical investigations. The further development of multimodal PET-MR and SPECT-MR imaging probes includes several key elements: novel synthetic strategies, high sensitivity for accurate quantification and high anatomic resolution, favourable pharmacokinetic profile and target-specific binding of a new probe. This review thoroughly summarizes all recently available and noteworthy PET-MR and SPECT-MR multimodal imaging probes including small molecule bimodal probes, nano-sized bimodal probes, small molecular trimodal probes and nano-sized trimodal probes. To the best of our knowledge, this is the first comprehensive overview of all PET-MR and SPECT-MR multimodal probes. Since the development of multimodal PET-MR and SPECT-MR imaging probes is an emerging research field, a selection of 139 papers were recognized following the literature review. The challenges for designing multimodal probes have also been addressed in order to offer some future research directions for this novel interdisciplinary research field.

Lineage-specific exosomes could override extracellular matrix mediated human mesenchymal stem cell differentiation

Lineage specification is an essential process in stem cell fate, tissue homeostasis and development. Microenvironmental cues provide direct and selective extrinsic signals to regulate lineage specification of stem cells. Microenvironmental milieu consists of two essential components, one being extracellular matrix (ECM) as the substratum, while the other being cell secreted exosomes and growth factors. ECM of differentiated cells modulates phenotypic expression of stem cells, while their exosomes contain phenotype specific instructive factors (miRNA, RNA and proteins) that control stem cell differentiation. This study demonstrates that osteoblasts-derived (Os-Exo) and adipocytes-derived (Ad-Exo) exosomes contain instructive factors that regulate the lineage specification of human mesenchymal stem cells (hMSCs). Analyses of exosomes revealed the presence of transcription factors in the form of RNA and protein for osteoblasts (RUNX2 and OSX) and adipocytes (C/EBPα and PPARγ). In addition, several miRNAs reported to have osteogenic and adipogenic differentiation potentials are also identified in these exosomes. Kinetic and differentiation analyses indicate that both osteoblast and adipocyte exosomes augment ECM-mediated differentiation of hMSCs into the respective lineage. The combination of osteoblast/adipocyte ECM and exosomes turned-on the lineage specific gene expressions at earlier time points of differentiation compared to the respective ECM or exosomes administered individually. Interestingly, the hMSCs differentiated on osteoblast ECM with adipogenic exosomes showed expression of adipogenic lineage genes, while hMSCs differentiated on adipocyte ECM with osteoblast exosomes showed osteogenic lineage genes. Based on these observations, we conclude that exosomes might override the ECM mediated instructive signals during lineage specification of hMSC.

Theranostic applications of nanoparticles in neurodegenerative disorders

The preeminent treatments for neurodegenerative disease are often unavailable due to the poor accessibility of therapeutic drugs. Moreover, the blood–brain barrier (BBB) effectively blocks the transfer of cells, particles and large molecules, ie, drugs, across the brain. The most important challenge in the treatment of neurodegenerative diseases is the development of targeted drug delivery system. Theranostic strategies are known to combine therapeutic and diagnostic capabilities together. The aim of this review was to record the response to treatment and thereby improve drug safety. Nanotechnology offers a platform for designing and developing theranostic agents that can be used as an efficient nano-carrier system. This is achieved by the manipulation of some of the properties of nanoparticles (NPs), thereby enabling the attachment of suitable drugs onto their surface. The results provide revolutionary treatments by stimulation and thus interaction with targeted sites to promote physiological response with minimum side effects. This review is a brief discussion of the administration of drugs across the brain and the advantages of using NPs as an effective theranostic platform in the treatment of Alzheimer’s, Parkinson’s, epilepsy and Huntington’s disease.

A tunable time-resolved spontaneous Raman spectroscopy setup for probing ultrafast collective excitation and quasiparticle dynamics in quantum materials

We present a flexible and efficient ultrafast time-resolved spontaneous Raman spectroscopy setup to study collective excitation and quasi-particle dynamics in quantum materials. The setup has a broad energy tuning range extending from the visible to near infrared spectral regions for both the pump excitation and Raman probe pulses. Additionally, the balance between energy and time-resolution can be controlled. A high light collecting efficiency is realized by high numerical aperture collection optics and a high-throughput flexible spectrometer. We demonstrate the functionality of the setup with a study of the zone-center longitudinal optical phonon and hole continuum dynamics in silicon and discuss the role of the Raman tensor in time-resolved Raman scattering. In addition, we show an evidence for unequal phonon softening rates at different high symmetry points in the Brillouin zone of silicon by means of detecting pump-induced changes in the two-phonon overtone spectrum. Demagnetization dynamics in the helimagnet Cu2OSeO3 is studied by observing softening and broadening of a magnon after photo-excitation, underlining the unique power of measuring transient dynamics in the frequency domain, and the feasibility to study phase transitions in quantum materials.