Polymeric functionalization of mesoporous silica nanoparticles: Biomedical insights.

Mesoporous silica nanoparticles (MSNs) endowed with polymer coatings present a versatile platform, offering notable advantages such as targeted, pH-controlled, and stimuli-responsive drug delivery. Surface functionalization, particularly through amine and carboxyl modification, enhances their suitability for polymerization, thereby augmenting their versatility and applicability. This review delves into the diverse therapeutic realms benefiting from polymer-coated MSNs, including photodynamic therapy (PDT), photothermal therapy (PTT), chemotherapy, RNA delivery, wound healing, tissue engineering, food packaging, and neurodegenerative disorder treatment. The multifaceted potential of polymer-coated MSNs underscores their significance as a focal point for future research endeavors and clinical applications. A comprehensive analysis of various polymers and biopolymers, such as polydopamine, chitosan, polyethylene glycol, polycaprolactone, alginate, gelatin, albumin, and others, is conducted to elucidate their advantages, benefits, and utilization across biomedical disciplines. Furthermore, this review extends its scope beyond polymerization and biomedical applications to encompass topics such as surface functionalization, chemical modification of MSNs, recent patents in the MSN domain, and the toxicity associated with MSN polymerization. Additionally, a brief discourse on green polymers is also included in review, highlighting their potential for fostering a sustainable future.

"Visualizing" the partially reversible conversion of gold nanoclusters via the Au23(S-c-C6H11)17 intermediate.

Transformation chemistry of atomically precise metal nanoclusters has emerged as a novel strategy for fundamental research on the structure-property correlations of nanomaterials. However, a thorough understanding of the transformation mechanism is indeed necessary to understand the structural growth patterns and corresponding property evolutions in nanoclusters. Herein, we present the ligand-exchange-induced transformation of the [Au23(SR)16]- (8e-) nanocluster to the [Au25(SR')18]- (8e-) nanocluster, through the Au23(SR)17 (6e-) intermediate species. Identification of this key intermediate through a partially reversible transformation helped in a detailed investigation into the transformation mechanism with atomic precision. Moreover, photophysical studies carried out on this Au23(SR)17 species, which only differs by a single ligand from that of the [Au23(SR)16]- nanocluster reveal the property evolutions at the slightest change in the nanocluster structure.

Epigenetic age oscillates during the day.

Since their introduction, epigenetic clocks have been extensively used in aging, human disease, and rejuvenation studies. In this article, we report an intriguing pattern: epigenetic age predictions display a 24-h periodicity. We tested a circadian blood sample collection using 17 epigenetic clocks addressing different aspects of aging. Thirteen clocks exhibited significant oscillations with the youngest and oldest age estimates around midnight and noon, respectively. In addition, daily oscillations were consistent with the changes of epigenetic age across different times of day observed in an independant populational dataset. While these oscillations can in part be attributed to variations in white blood cell type composition, cell count correction methods might not fully resolve the issue. Furthermore, some epigenetic clocks exhibited 24-h periodicity even in the purified fraction of neutrophils pointing at plausible contributions of intracellular epigenomic oscillations. Evidence for circadian variation in epigenetic clocks emphasizes the importance of the time-of-day for obtaining accurate estimates of epigenetic age.

Probing the Potential: Exploring Probiotics as a Novel Frontier in Cancer Prevention and Therapeutics.

Cancer has emerged as one of the most prevalent diseases worldwide, with a consistent rise in the number of cases observed over the past few decades. The rising mortality rates associated with cancer have transformed it into a significant global challenge. Despite the presence of various anti-cancer drugs, the complete eradication of cancer remains an elusive goal. The numerous undesirable effects associated with cancer therapy further emphasize the importance of developing an alternative technique of cancer treatment. Recent research has established the beneficial effects of a probiotic diet or supplementation against cancer without displaying any detrimental consequences. An alteration in the gut microbiome balance in humans can result in the development of various diseases, including cancer. Probiotics play a pivotal role in restoring the balance of gut flora, potentially contributing to cancer prevention. Furthermore, they have the capacity to curb the invasion and dissemination of infections that carry the risk of triggering cancer. Probiotics can combat cancer in various ways, such as by eliciting and boosting the immune response, secreting metabolites, preventing cancer cells from metastasizing, inhibiting carcinogenic chemicals, and mitigating their toxicity, etc. The present review intends to outline the significance of probiotics and their underlying mechanisms in combating various cancer types. Additionally, this review highlights the benefits of probiotic use in pre- and post-operative cancer patients.

Bilayer and Trilayer C3N/Blue-Phosphorene Heterostructures as Potential Anode Materials for Potassium-Ion Batteries.

Two-dimensional (2D) van der Waals heterostructures outperform conventional anode materials for postlithium-ion batteries in terms of mechanical, thermal, and electrochemical properties. This study systemically investigates the performance of bilayer and trilayer C3N/blue phosphorene (C3N/BlueP) heterostructures as anode materials for potassium-ion batteries (KIBs) using first-principles density functional theory calculations. This study reveals that the adsorption and diffusion of K ions on bilayer and trilayer C3N/BlueP heterostructures are markedly superior to those of their monolayer counterparts. A bilayer heterostructure (C3N/BlueP) effectively reduces the bandgap of the BlueP monolayer (1.98 eV) to 0.02 eV, whereas trilayer heterostructures (bilayer-C3N/BlueP and C3N/bilayer-BlueP) exhibit metallic behavior with no bandgap. Additionally, the theoretical capacity of the bilayer and trilayer heterostructures ranges from 636.7 to 755.5 mA h g-1, considerably higher than the theoretical capacity of other prospective 2D heterostructures for KIBs investigated in the literature. This study also shows that the heterostructures exhibit K-ion diffusion barriers as low as 0.042 eV, ensuring the relatively fast diffusion of K ions.

Control over product formation and thermodynamic stability of thiolate-protected gold nanoclusters through tuning of surface protecting ligands.

Surface-protecting ligands can regulate the structure of a cluster's core either through electronic or steric effects. However, the influence of the steric effect along with the electronic effect over controlling the structure during ligand exchange reactions remains elusive. To understand this, we have carried out ligand exchange on [Au23(CHT)16]- (CHT: cyclohexane thiol) using aromatic thiolates where we have tuned the bulkiness at the para position of the thiolate group on the incoming ligands. The outcome of the experiments reveals that each of the ligands in the chosen series is precisely selective towards the parent cluster transformation through specific intermediates. The ligand with more steric crowding directed the reaction pathway to have Au28 nanocluster as the major product while Au36 was the final product obtained with the gradual decrease of bulkiness over the ligand. The combined experimental and theoretical results elucidated the mechanism of the reaction pathways, product formation, and their stability. Indeed, this study with the series of ligands will add up to the ligand library, where we can decide on the ligand to obtain our desired cluster for specific applications through the ligand exchange reaction.

A luminescent Cu4 cluster film grown by electrospray deposition: a nitroaromatic vapour sensor.

We present the fabrication and use of a film of a carborane-thiol-protected tetranuclear copper cluster with characteristic orange luminescence using ambient electrospray deposition (ESD). Charged microdroplets of the clusters produced by an electrospray tip deposit the clusters at an air-water interface to form a film. Different microscopic and spectroscopic techniques characterized the porous surface structure of the film. Visible and rapid quenching of the emission of the film upon exposure to 2-nitrotoluene (2-NT) vapours under ambient conditions was observed. Density functional theory (DFT) calculations established the favourable binding sites of 2-NT with the cluster. Desorption of 2-NT upon heating recovered the original luminescence, demonstrating the reusability of the sensor. Stable emission upon exposure to different organic solvents and its quenching upon exposure to 2,4-dinitrotoluene and picric acid showed selectivity of the film to nitroaromatic species.

Exploring Mushroom Polysaccharides for the Development of Novel Prebiotics: A Review.

Prebiotics have gained much attention in recent years as functional food ingredients. This has encouraged researchers to look for sustainable alternative sources of prebiotics. Prebiotics help in the modulation of the human intestinal microbiota and thereby improve host health. Chicory, asparagus, and Jerusalem artichoke are some conventional prebiotics that have been extensively studied. Mushrooms are rich sources of medicinal foods as well as bioactive polysaccharides and essential amino acids. They contain large amounts of chitin, mannans, galactans, xylans, glucans, krestin, lentinan, and hemicellulose, thus making it a potential candidate for prebiotics. They are also rich sources of fibers, proteins, and antioxidants. Several mushroom species like Ganoderma lucidum, Pleurotus ostreatus, Hericium erinaceus, Agaricus bisporus, and Lentinula edodes are rich in medicinal properties that have an array of applications. These medicinal mushrooms can be repurposed to regulate gut microbiota. In this review, we discuss the prebiotic effects of different mushroom species on probiotic organisms. We also reviewed the potential of mushroom waste as novel, cheap, and alternative sources of prebiotics.

[Cu18H3(S-Adm)12(PPh3)4Cl2]: fusion of Platonic and Johnson solids through a Cu(0) center and its photophysical properties.

Structural elucidation of atom-precise thiolate-protected copper nanoclusters (Cu NCs) containing Cu(0) is quite challenging. Here, we report a new adamantane-thiol-protected NC, [Cu18H3(S-Adm)12(PPh3)4Cl2] (Cu18), which represents the first observation of a rare mononuclear Cu(0)-containing Cu10H3Cl2 core that is constructed via kernel fusion through vertex sharing of the Platonic-solid- and Johnson-solid-geometry-like kernels and hydride-bridging. The unique core is surrounded by a Cu8S12P4 metal-ligand motif shell and adopts a butterfly-like structure. In comparison to its closest structural analogue, the predominant effect of the principal Cu atom vacancy-induced structural rearrangement is evidenced. The occupied orbitals of this NC have a major d-orbital contribution to the distorted Cu6 octahedral kernel, whereas unoccupied orbitals owe a contribution to the distorted Cu5 square-pyramidal kernel. Thus, the charge transfer phenomenon is uniquely instigated between the two fused kernels through Cu(d) → Cu(d) transition via the Cu(0) center. This NC exhibits violet emission due to kernel-dominated relaxation at room temperature, which is further enhanced by confining the surface protecting ligands through recognition-site-specific host-guest supramolecular adduct formation by ß-cyclodextrin. The unique electronic structure of this NC further facilitates its application toward photocurrent generation. Thus, this study offers a unique strategy for the controllable synthesis of a Cu(0)-containing Cu NC, which enables atomic-level insights into their optoelectronic properties.

Relativistic Effects in Platinum Nanocluster Catalysis: A Statistical Ensemble-Based Analysis.

Nanoclusters are materials of paramount catalytic importance. Among various unique properties featured by nanoclusters, a pronounced relativistic effect can be a decisive parameter in governing their catalytic activity. A concise study delineating the role of relativistic effects in nanocluster catalysis is carried by investigating the oxygen reduction reaction (ORR) activity of a Pt7 subnanometer cluster. Global optimization analysis shows the critical role of spin-orbit coupling (SOC) in regulating the relative stability between structural isomers of the cluster. An overall improved ORR adsorption energetics and differently scaled adsorption-induced structural changes are identified with SOC compared to a non-SOC scenario. Ab initio atomistic thermodynamics analysis predicted nearly identical phase diagrams with significant structural differences for high coverage oxygenated clusters under realistic conditions. Though inclusion of SOC does not bring about drastic changes in the overall catalytic activity of the cluster, it is having a crucial role in governing the rate-determining step, transition-state configuration, and energetics of elementary reaction pathways. Furthermore, a statistical ensemble-based approach illustrates the strong contribution of low-energy local minimum structural isomers to the total ORR activity, which is significantly scaled up along the activity improving direction within the SOC framework. The study provides critical insights toward the importance of relativistic effects in determining various catalytic activity relevant features of nanoclusters.

Computational Screening of First-Row Transition-Metal Based Alloy Catalysts-Ligand Induced N2 Reduction Reaction Selectivity.

Large-scale ammonia production through sustainable strategies from naturally abundant N2 under ambient conditions represents a major challenge from a future perspective. Ammonia is one of the promising carbon-free alternative energy carriers. The high energy required for N≡N bond dissociation during the Haber-Bosch process demands extreme reaction conditions. This problem could be circumvented by tuning Fe catalyst composition with the help of an induced ligand effect on the surface. In this work, we utilized density functional theory calculations on the Fe(110) surface alloyed with first-row transition-metal (TM) series (Fe-TM) to understand the catalytic activity that facilitates the electrochemical nitrogen reduction reaction (NRR). We also calculated the selectivity against the competitive hydrogen evolution reaction (HER) under electrochemical conditions. The calculated results are compared with those from earlier reports on the periodic Fe(110) and Fe(111) surfaces, and also on the (110) surface of the Fe85 nanocluster. Surface alloying with late TMs (Co, Ni, Cu) shows an improved NRR activity, whereas the low exchange current density observed for Fe-Co indicates less HER activity among them. Considering various governing factors, Fe-based alloys with Co (Fe-Co) showed enhanced overall performance compared to the periodic surface as well as other pure iron-based structures previously reported. Therefore, the iron-alloy based structured catalysts may also provide more opportunities in the future for enhancing NRR performance via electrochemical reduction pathways.

Role of Ligand on Photophysical Properties of Nanoclusters with fcc Kernel: A Case Study of Ag14(SC6H4X)12(PPh3)8 (X = F, Cl, Br).

The structure-property correlation of a series of silver nanoclusters (NCs) is essential to understand the origin of photophysical properties. Here, we report a series of face-centered cubic (fcc)-based silver NCs by varying the halogen atom in the thiolate ligand to investigate the influence of the halide atoms on the electronic structure. These are {Ag14(FBT)12(PPh3)8·(solvent)x} (NC-1), Ag14(CBT)12(PPh3)8 (NC-2), and Ag14(BBT)12(PPh3)8 (NC-3), where 4-fluorothiophenol (FBT), 4-chlorothiophenol (CBT), and 4-bromothiophenol (BBT) have been utilized as thiolate ligands, respectively. Interestingly, the optical and electrochemical bandgap values of these NCs nicely correlated with the electronic effect of the halides, which is governed by the intracluster and interclusters π-π interactions. These clusters are emissive at room temperature and the luminescence intensity increases with the lowering of temperature. The short lifetime data suggest that the emission is predominantly originating due to the interband relaxation (d → sp) of the Ag cores. Femtosecond transient absorption (TA) spectra revealed similar types of decay profiles for NC-2 and NC-3 and longer decay time for NC-2. The relaxation dominates the decay profile to the surface states and most of the excited-state energy dissipates via this process. This supports the molecular-like dynamics of these series of NCs with an fcc core. This overview shed light on an in-depth understanding of ligand's role in luminescence and transient absorption spectra.

Gold Deassembly: From Au44(SPh-tBu)28 to Au36(SPh-tBu)24 Nanocluster through Dynamic Surface Structure Reconstruction.

Molecular level understanding of the structural growth patterns and property evolution in nanoclusters (NCs) is crucial for the design and rational synthesis of clusters for specific properties and applications. In this regard, transformation has always been a versatile approach to achieve atomic precision with atomic purity and a deeper understanding of the growth mechanisms of noble metal NCs. To the latter end, we have demonstrated a structural transformation of Au44(SPh-tBu)28 to Au36(SPh-tBu)24 NC, which occurred through the deassembly of an Au8(SPh-tBu)4 fragment. Kinetic studies conducted on the transformation showed that it follows zero-order kinetics with a low activation energy pathway. Theoretical studies demonstrated that this process happens via surface restructuring of the core-ligand interface, which was found to be the rate-determining step of this transformation. Based on this, a plausible mechanistic pathway for the transformation have been proposed which we envision, will provide useful insights into NC structure evolution.

Role of atomicity in the oxygen reduction reaction activity of platinum sub nanometer clusters: A global optimization study.

Metal nanoclusters are an important class of materials for catalytic applications. Sub nanometer clusters are relatively less explored for their catalytic activity on account of undercoordinated surface structure. Taking this into account, we studied platinum-based sub nanometer clusters for their catalytic activity for oxygen reduction reaction (ORR). A comprehensive analysis with global optimization is carried out for structural prediction of the platinum clusters. The energetic and electronic properties of interactions of clusters with reaction intermediates are investigated. The role of structural sensitivity in the dynamics of clusters is unraveled, and unique intermediate specific interactions are identified. ORR energetics is examined, and exceptional activity for sub nanometer clusters are observed. An inverse size versus activity relationship is identified, challenging the conventional trends followed by larger nanoclusters. The principal role of atomicity in governing the catalytic activity of nanoclusters is illustrated. The structural norms governing the sub nanometer cluster activity are shown to be markedly different from larger nanoclusters.

Response surface methodology and artificial neural network modelling for the performance evaluation of pilot-scale hybrid nanofiltration (NF) & reverse osmosis (RO) membrane system for the treatment of brackish ground water.

Artificial neural network (ANN) and response surface methodology (RSM) were employed to develop models for process optimisation of pilot scale nanofiltration (NF) and reverse osmosis (RO) membrane filtration system for the treatment of brackish groundwater. The process variables for this study were feed concentration, temperature, pH and pressure. The performance of NF/RO was assessed in terms of permeate flux, water recovery, salt rejection and specific energy consumption, which were considered as responses. The experimental design was employed to develop both RSM and ANN models. RSM model was validated for the whole range of experimental levels, while the ANN model was considered for the whole range of experimental design. RSM and ANN models were statistically analysed using analysis of variance (ANOVA). Further, the models were graphically compared for its predictive capacity. Numerical optimisation of NF and RO pilot plant to determine the optimum conditions were verified. Finally, using the optimum conditions, three hybrid configurations of NF and RO were studied to determine the best mode for the treatment of brackish groundwater. It was found that parallel NF-RO had a recovery of 57.18% and rejection of 44.89%, for RO-concentrate-NF (RO-C-NF) recovery was 49.55% and rejection of 38.64% & for NF-concentrate-RO (NF-C-RO), the recovery of 39.53% and rejection of 49.66% was obtained. Results obtained also suggested that the mode of configurations and the feed concentration affect the performance of the hybrid system.

Synergistic Effect of Bridging Thiolate and Hub Atoms for the Aromaticity Driven Symmetry Breaking in Atomically Precise Gold Nanocluster.

The symmetry of atomically precise nanoclusters is influenced by the specific geometry of the kernel and the arrangement of staple motifs. To understanding the role of ligand and its effect on the breaking of symmetry during ligand exchange transformation, it is necessary to have a mechanism of transformation in an atomically precise manner. Herein, we report the structural transformation from bipyramidal kernel to icosahedral kernel via ligand exchange. The transformation of [Au23(CHT)16]- to [Au25(2-NPT)18]- through ligand (aromatic) exchange revealed two important principles. First, the combined effort of experimental and theoretical study on structural analysis elucidated the mechanism of this structural transformation where "bridging thiolate" and "hub" gold atoms play a crucial role. Second, we have found that the higher crystal symmetry of the Au23 cluster is broken to lower crystal symmetry during the ligand exchange process. This showed that during ligand exchange, the hub atoms and µ3-S atoms get distorted and contributed to the ligand-staple motif formation. These phenomena specified that the ligand effects might be the pivotal factor to impose lower symmetry of the crystal system in the product clusters.

Defects Engineering on Ceria and C-C Coupling Reactions Using [Au11(PPh3)7I3] Nanocluster: A Combined Experimental and Theoretical Study.

Ligand protected atom-precise gold-based catalysts have been utilized in many essential chemical processes, but their mechanism and the fate of the catalyst during reaction are still unrevealed. Atom-precise cluster without ligands are thus highly desirable to maximize atom efficiency, but making these in solution phase is challenging. In this scenario, catalysts with dispersion on oxide support are highly desirable to understand the role of metal core during catalytic reaction. Here, we report the synthesis of Au11(PPh3)7I3 cluster that consists of an incomplete icosahedron core. During its impregnation process on CeO2 support, all of the ligands were removed from the kernel and the Au11 kernel fits into the defects of ceria (embedded onto the oxygen vacancy of ceria (111) plane). This Au11@CeO2 has high atom efficiency and catalytic activity for Ullmann-type C-C homocoupling reactions for electron rich substrates. Density functional theory calculations showed that hexagonal arrangements of Au11 kernel on (111) plane of CeO2 is the most stable one. Theoretical calculations also proved that the atop gold atom has more favorable interaction with phenyl iodide than the second layer gold atoms of the Au11@CeO2. This demonstrated that the present catalyst mimics the single-atom catalyst-like behavior in facilitating the coupling reactions.

Size Evolution Dynamics of Gold Nanoclusters at an Atom-Precision Level: Ligand Exchange, Growth Mechanism, Electrochemical, and Photophysical Properties.

Interpretation of size evolution is an essential part of nanocluster transformation processes for unraveling the mechanism at an atom-precision level. Here we report the transformation of a non-superatomic Au23 to a superatomic Au36 nanocluster via Au28 cluster formation, activated by the bulky 4-tert-butylbenzenethiol ligand. Time-dependent matrix-assisted laser desorption ionization mass spectrometry data revealed that the conversion proceeds through ligand exchange followed by the size focusing method, ultimately leading to size growth. We also validated this transformation through time-dependent ultraviolet-visible data. Density functional theory calculations predicted that the kernel of the Au28 cluster evolved through a linear combination of molecular orbitals of the fragment of 2e- units (Au42+ and Au3+) from the kernel of the Au23 cluster. Periodic growth of gold cores through continuous growth of Au4 tetrahedral unit leads to the formation of the Au36 cluster from the Au28 cluster. These results reinforce the plausibility of size evolution through the growth mechanism during the transformation process. Differential pulse voltammetry studies showed that the highest occupied molecular orbital-lowest unoccupied molecular orbital gap inversely varies with the kernel size of these clusters. Photophysical experiments support the molecular-like intersystem crossing rather than core-shell relaxation to these clusters. The trends of photoluminescence lifetime were found to be the reverse of those of the energy gap law. The increment of lifetimes for the larger cluster can be mainly due to the contribution of both hot carriers and band-edge carriers.

Unraveling the single-atom electrocatalytic activity of transition metal-doped phosphorene.

The development of single-atom catalysts (SACs) for chemical reactions of vital importance in the renewable energy sector has emerged as an urgent priority. In this perspective, transition metal-based SACs with monolayer phosphorous (phosphorene) as the supporting material are scrutinized for their electrocatalytic activity towards the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) from first-principle calculations. The detailed screening study has confirmed a breaking of the scaling relationship between the ORR/OER intermediates, resulting in various activity trends across the transition metal series. Groups 9 and 10 transition metal-based SACs are identified as potential catalyst candidates with the platinum single atom offering bifunctional activity for OER and HER with diminished overpotentials. Ambient condition stability analysis of SACs confirmed a different extent of interaction towards oxygen and water compared to pristine phosphorene, suggesting room for improving the stability of phosphorene via chemical functionalization.

Prescription Audit of Treatment of Diarrhoea and Pneumonia Amongst Paediatrician In Bhopal.

BACKGROUND: A prescription by a doctor may be taken as a reflection of physician's attitude to the disease. Inappropriate prescription has always been a serious problem in developing countries. OBJECTIVES: The objective was to observe the current prescription practices for the management of diarrhea and pneumonia in Bhopal. SETTINGS AND DESIGN: This was a cross-sectional study. MATERIALS AND METHODS: The study was conducted at the clinics and hospitals of Bhopal over 4 months. The prescription of under-5 children with a diagnosis of acute respiratory tract infection and/or acute gastroenteritis attending the outpatient departments was included in the study. Data were recorded and analysis was done. STATISTICAL ANALYSIS USED: Epi Info was used for statistical analysis. RESULTS: A total of 513 prescriptions of pneumonia and 417 of diarrhea were observed under the study. Among pneumonia, signs were mentioned on 15.6%, 74% as cold and cough with 95.5% prescriptions with antimicrobials. Seventy-three percent of diarrhea prescriptions did not mention any signs. Oral rehydration salt and zinc were prescribed in majority of the prescriptions along with around 64% use of antibiotics as well for the treatment of diarrhea. CONCLUSION: There is a huge need of improvement in prescribing patterns in areas of complete prescriptions with clinical features, follow-up advice along with rational choice of drugs with dose, and duration.