The Role of Ligands in the Chemical Synthesis and Applications of Inorganic Nanoparticles.

The design of nanoparticles is critical for their efficient use in many applications ranging from biomedicine to sensing and energy. While shape and size are responsible for the properties of the inorganic nanoparticle core, the choice of ligands is of utmost importance for the colloidal stability and function of the nanoparticles. Moreover, the selection of ligands employed in nanoparticle synthesis can determine their final size and shape. Ligands added after nanoparticle synthesis infer both new properties as well as provide enhanced colloidal stability. In this article, we provide a comprehensive review on the role of the ligands with respect to the nanoparticle morphology, stability, and function. We analyze the interaction of nanoparticle surface and ligands with different chemical groups, the types of bonding, the final dispersibility of ligand-coated nanoparticles in complex media, their reactivity, and their performance in biomedicine, photodetectors, photovoltaic devices, light-emitting devices, sensors, memory devices, thermoelectric applications, and catalysis.

Variations in Biodistribution and Acute Response of Differently Shaped Titania Nanoparticles in Healthy Rodents.

Titanium dioxide nanoparticles (TiO2 NPs) are one of the main sources of the nanoparticulate matter exposure to humans. Although several studies have demonstrated their potential toxic effects, the real nature of the correlation between NP properties and their interaction with biological targets is still far from being fully elucidated. Here, engineered TiO2 NPs with various geometries (bipyramids, plates, and rods) have been prepared, characterized and intravenously administered in healthy mice. Parameters such as biodistribution, accumulation, and toxicity have been assessed in the lungs and liver. Our data show that the organ accumulation of TiO2 NPs, measured by ICP-MS, is quite low, and this is only partially and transiently affected by the NP geometries. The long-lasting permanence is exclusively restricted to the lungs. Here, bipyramids and plates show a higher accumulation, and interestingly, rod-shaped NPs are the most toxic, leading to histopathological pulmonary alterations. In addition, they are also able to induce a transient increase in serum markers related to hepatocellular injury. These results indicate that rods, more than bipyramidal and spherical geometries, lead to a stronger and more severe biological effect. Overall, small physico-chemical differences can dramatically modify both accumulation and safety.

The Predictors Of Re-Bleeding In Chronic Liver Disease Patients After Endoscopic Variceal Band Ligation.

BACKGROUND: Variceal bleeding is a key and most fatal complication observed in chronic liver disease patients with portal hypertension and is a major contributor to the high morbidity and mortality seen in these patients. Exploring the predictors of rebleeding in chronic liver disease patients is of paramount importance to alter disease course and impact on morbidity and mortality. METHODS: About 50 patients with chronic liver disease who previously had evidence of varices on upper GI endoscopy and had at least one episode of rebleeding after EVBL were included in this study. Patients were assessed for the possible contributors to rebleeding through complete history, clinical examination, coagulation profile and platelet count, ultrasound features (splenic size and portal pressure), and upper GI endoscopic findings (site and grade of varices, red sign). Sample selection was done using non-probability purposive sampling technique and sample size calculated using the standard WHO formula. Data was entered and analyzed using SPSS version 20. RESULTS: In this study, mean age of the patients was 51.34±6.34 years with male predominance (64%). Rebleeding was significantly associated with grade of varices, presence of red sign on upper GI endoscopy, site of varices, splenic size and coagulopathy. CONCLUSIONS: Rebleeding in chronic liver disease patients following EVBL is predicted by grade, extent and site of varices, red sign on upper GI endoscopy, splenic size and coagulation disturbances.

Thermoluminescence (TL), kinetic parameters and dosimetric features of Pakistani limestone.

Thermoluminescence (TL), kinetic parameters and dosimetric features of Pakistani limestone (CaCO3) is reported in this study. Both compositional and structural analyses reveal that the material has a crystalline nature with rhombohedral structure and non-uniform crystallite size having major content of CaCO3. A powdered limestone sample of 30 mg is found to be the optimized weight for TL and other dosimetric studies. After irradiating the samples with a test dose of 100 Gy using a ß source three composite glow peaks termed as P1, P2 and P3 are visible at 100, 230 and 330 °C respectively using a linear heating rate of 1 °C/s during the TL readout. The Coefficient of Variation (COV) is found to be about 4%. Kinetic parameters (i.e., frequency factor (f), activation energy (E), and the kinetic order (b)) are estimated using both first and second Order of kinetics using an in-house Computerized Glow Curve Deconvolution (GCD) software. The figure-of-merit (FOM) is found to be 2.12%. The distribution of continuum traps with activation energy in the range of 0.77-2.59 eV is observed in the kinetic parameter analysis of the glow peaks of the sample. The TL response in the dose range of 1-5 Gy (not reported previously) and linearity in the dose response in the dose range of 1-10 Gy is observed in samples of Pakistani limestone. The Minimum Detectable Dose (MDD) is 1.01 Gy clearly resembling the experimentally linear fitted results. After a fading study for a period of thirty days, only the first peak i.e., P1 majorly fades while no major change is observed in the amplitude of peaks P2 and P3. In addition, P1 is the main contributor fading by 92% within the first 24 h of irradiation while P2 fades by 30 %. However, P3 shows stability with a very minor fading of 0.05% within 24 h of irradiation. This study concludes that Pakistani limestone can be further assessed as a potential radiation dosimeter for various applications.

The psychological impact of COVID-19 on healthcare workers in Pakistan.

INTRODUCTION: The COVID-19 pandemic has challenged healthcare facilities and healthcare professionals' stamina and wellbeing. This study examines the psychological impact of COVID-19 on healthcare professionals. METHODS: This analytical cross-sectional study was conducted in July 2020 after institutional review board approval at a tertiary care institution in Lahore, Pakistan. A total of 175 healthcare workers participated following an online Depression, Anxiety and Stress Scale-21 (DASS-21) questionnaire invitation and 41 were excluded following pre-existing mental health conditions. Data was analysed using MS Excel and SPSS Amos 23. Chi-squared test and regression were applied for comparison and impact of confounding variables respectively (p<0.05 was considered significant). RESULTS: Out of 134, 66 (49%) were doctors, 24 (18%) were nurses and 44 (33%) were non-medical professionals. Ninety-five (70%) with age 21-30 years. Male to female ratio was 2:1. Overall mean depression score accounted for 6.89 ± 6.64; anxiety score was 7.28 ± 6.74 and stress score was 8.83 ± 6.93. Mild depression, anxiety and stress was noted in 21 (15.6%), eight (6%) and 27 (20.1%) healthcare workers, respectively. A statistically significant difference (p<0.05) was observed among healthcare workers for depression, anxiety and stress. CONCLUSION: This study demonstrated considerable impact of COVID-19 on mental health of healthcare workers. A well-structured targeted mental health support programme is needed urgently to support and reduce the long-term impact on healthcare workers' mental health and wellbeing.

Aerogelation of Polymer-Coated Photoluminescent, Plasmonic, and Magnetic Nanoparticles for Biosensing Applications.

Macroscopic materials with nanoscopic properties have recently been synthesized by self-assembling defined nanoparticles to form self-supported networks, so-called aerogels. Motivated by the promising properties of this class of materials, the search for versatile routes toward the controlled assembly of presynthesized nanoparticles into such ultralight macroscopic materials has become a great interest. Overcoating procedures of colloidal nanoparticles with polymers offer versatile means to produce aerogels from nanoparticles, regardless of their size, shape, or properties while retaining their original characteristics. Herein, we report on the surface modification and assembly of various building blocks: photoluminescent nanorods, magnetic nanospheres, and plasmonic nanocubes with particle sizes between 5 and 40 nm. The polymer employed for the coating was poly(isobutylene-alt-maleic anhydride) modified with 1-dodecylamine side chains. The amphiphilic character of the polymer facilitates the stability of the nanocrystals in aqueous media. Hydrogels are prepared via triggering the colloidally stable solutions, with aqueous cations acting as linkers between the functional groups of the polymer shell. Upon supercritical drying, the hydrogels are successfully converted into macroscopic aerogels with highly porous, open structure. Due to the noninvasive preparation method, the nanoscopic properties of the building blocks are retained in the monolithic aerogels, leading to the powerful transfer of these properties to the macroscale. The open pore system, the universality of the polymer-coating strategy, and the large accessibility of the network make these gel structures promising biosensing platforms. Functionalizing the polymer shell with biomolecules opens up the possibility to utilize the nanoscopic properties of the building blocks in fluorescent probing, magnetoresistive sensing, and plasmonic-driven thermal sensing.

A Case of Vogt-Koyanagi-Harada Syndrome Mimicking Optic Neuritis.

Vogt-Koyanagi-Harada syndrome is a rare disease that occurs commonly in pigmented individuals of Asian origin. A 25-year female presented in medical outpatient department (OPD) of Al-Khidmat Teaching Hospital, Mansoora, Lahore with headache and neck stiffness. She was referred to eye OPD for the complaint of decreased vision. On examination, there was 6/24 vision, sluggish pupillary reaction and disc hyperemia in both eyes. She was treated as a case of optic neuritis. Few days later, she developed bilateral panuveitis, shallow exudative detachments and alopecia. Clinical picture with normal magnetic resonance imaging (MRI) and laboratory tests helped us in reaching the diagnosis of Vogt-Koyanagi-Harada syndrome.

Dissociation coefficients of protein adsorption to nanoparticles as quantitative metrics for description of the protein corona: A comparison of experimental techniques and methodological relevance.

Protein adsorption to nanoparticles is described as a chemical reaction in which proteins attach to binding sites on the nanoparticle surface. This process is defined by a dissociation coefficient, which tells how many proteins are adsorbed per nanoparticle in dependence of the protein concentration. Different techniques to experimentally determine dissociation coefficients of protein adsorption to nanoparticles are reviewed. Results of more than 130 experiments in which dissociation coefficients have been determined are compared. Data show that different methods, nanoparticle systems, and proteins can lead to significantly different dissociation coefficients. However, we observed a clear tendency of smaller dissociation coefficients upon less negative towards more positive zeta potentials of the nanoparticles. The zeta potential thus is a key parameter influencing protein adsorption to the surface of nanoparticles. Our analysis highlights the importance of the characterization of the parameters governing protein-nanoparticle interaction for quantitative evaluation and objective literature comparison.

Quantitative uptake of colloidal particles by cell cultures.

The use of nanotechnologies involving nano- and microparticles has increased tremendously in the recent past. There are various beneficial characteristics that make particles attractive for a wide range of technologies. However, colloidal particles on the other hand can potentially be harmful for humans and environment. Today, complete understanding of the interaction of colloidal particles with biological systems still remains a challenge. Indeed, their uptake, effects, and final cell cycle including their life span fate and degradation in biological systems are not fully understood. This is mainly due to the complexity of multiple parameters which need to be taken in consideration to perform the nanosafety research. Therefore, we will provide an overview of the common denominators and ideas to achieve universal metrics to assess their safety. The review discusses aspects including how biological media could change the physicochemical properties of colloids, how colloids are endocytosed by cells, how to distinguish between internalized versus membrane-attached colloids, possible correlation of cellular uptake of colloids with their physicochemical properties, and how the colloidal stability of colloids may vary upon cell internalization. In conclusion three main statements are given. First, in typically exposure scenarios only part of the colloids associated with cells are internalized while a significant part remain outside cells attached to their membrane. For quantitative uptake studies false positive counts in the form of only adherent but not internalized colloids have to be avoided. pH sensitive fluorophores attached to the colloids, which can discriminate between acidic endosomal/lysosomal and neutral extracellular environment around colloids offer a possible solution. Second, the metrics selected for uptake studies is of utmost importance. Counting the internalized colloids by number or by volume may lead to significantly different results. Third, colloids may change their physicochemical properties along their life cycle, and appropriate characterization is required during the different stages.