Revisiting El-Sayed Synthesis: Bayesian Optimization for Revealing New Insights during the Growth of Gold Nanorods.

In diverse fields, machine learning (ML) has sparked transformative changes, primarily driven by the wealth of big data. However, an alternative approach seeks to mine insights from "precious data", offering the possibility to reveal missed knowledge and escape potential knowledge traps. In this context, Bayesian optimization (BO) protocols have emerged as crucial tools for optimizing the synthesis and discovery of a broad spectrum of compounds including nanoparticles. In our work, we aimed to go beyond the commonly explored experimental conditions and showcase a workflow capable of unearthing fresh insights, even in well-studied research domains. The growth of AuNRs is a nonequilibrium process that remains poorly understood despite the presence of well-established seeded growth protocols. Traditional research aimed at understanding the mechanism of AuNR growth has primarily relied on altering one reaction condition at a time. While these studies are undeniably valuable, they often fail to capture the synergies between different reaction conditions, thus constraining the depth of insights they can offer. In the present study, we exploit BO, to identify diverse experimental conditions yielding AuNRs with similar spectroscopic characteristics. Notably, we identify viable and accelerated synthesis conditions involving elevated temperatures (36-40 °C) as well as high ascorbic acid concentrations. More importantly, we note that ascorbic acid and temperature can modulate each other's undesirable influences on the growth of AuNRs. Finally, by harnessing the power of interpretable ML algorithms, complemented by our deep chemical understanding, we revisited the established hierarchical relationships among reaction conditions that impact the El-Sayed-based growth of AuNRs.

Temperature-Modulated Reversible Clustering of Gold Nanorods Driven by Small Surface Ligands.

Temperature-modulated colloidal phase of plasmonic nanoparticles is a convenient playground for resettable soft-actuators or colorimetric sensors. To render reversible clustering under temperature change, bulky ligands are required, especially if anisotropic morphologies are of interest. This study showcases thermoresponsive gold nanorods by employing small surface ligands, bis (p-sulfonatophenyl) phenyl-phosphine dihydrate dipotassium salt (BSPP) and native cationic surfactant. Temperature-dependent analysis in real-time allowed to describe the structural features (interparticle distance and cluster size) as well as thermal parameters, melting and freezing temperatures. These findings suggest that neither covalent Au-S bonds nor bulky ligands are required to obtain a robust thermoresponsive system based on anisotropic gold nanoparticles, paving the way to stimuli-responsive nanoparticles with a wide range of sizes and geometries.

Capillary Assembly of Anisotropic Particles at Cylindrical Fluid-Fluid Interfaces.

The unique behavior of colloids at liquid interfaces provides exciting opportunities for engineering the assembly of colloidal particles into functional materials. The deformable nature of fluid-fluid interfaces means that we can use the interfacial curvature, in addition to particle properties, to direct self-assembly. To this end, we use a finite element method (Surface Evolver) to study the self-assembly of rod-shaped particles adsorbed at a simple curved fluid-fluid interface formed by a sessile liquid drop with cylindrical geometry. Specifically, we study the self-assembly of single and multiple rods as a function of drop curvature and particle properties such as shape (ellipsoid, cylinder, and spherocylinder), contact angle, aspect ratio, and chemical heterogeneity (homogeneous and triblock patchy). We find that the curved interface allows us to effectively control the orientation of the rods, allowing us to achieve parallel, perpendicular, or novel obliquely orientations with respect to the cylindrical drop. In addition, by tuning particle properties to achieve parallel alignment of the rods, we show that the cylindrical drop geometry favors tip-to-tip assembly of the rods, not just for cylinders, but also for ellipsoids and triblock patchy rods. Finally, for triblock patchy rods with larger contact line undulations, we can achieve strong spatial confinement of the rods transverse to the cylindrical drop due to the capillary repulsion between the contact line undulations of the particle and the pinned contact lines of the sessile drop. Our capillary assembly method allows us to manipulate the configuration of single and multiple rod-like particles and therefore offers a facile strategy for organizing such particles into useful functional materials.

Nanoparticle Self-Assembly: From Design Principles to Complex Matter to Functional Materials.

The creation of matter with varying degrees of complexities and desired functions is one of the ultimate targets of self-assembly. The ability to regulate the complex interactions between the individual components is essential in achieving this target. In this direction, the initial success of controlling the pathways and final thermodynamic states of a self-assembly process is promising. Despite the progress made in the field, there has been a growing interest in pushing the limits of self-assembly processes. The main inception of this interest is that the intended self-assembled state, with varying complexities, may not be "at equilibrium (or at global minimum)", rendering free energy minimization unsuitable to form the desired product. Thus, we believe that a thorough understanding of the design principles as well as the ability to predict the outcome of a self-assembly process is essential to form a collection of the next generation of complex matter. The present review highlights the potent role of finely tuned interparticle interactions in nanomaterials to achieve the preferred self-assembled structures with the desired properties. We believe that bringing the design and prediction to nanoparticle self-assembly processes will have a similar effect as retrosynthesis had on the logic of chemical synthesis. Along with the guiding principles, the review gives a summary of the different types of products created from nanoparticle assemblies and the functional properties emerging from them. Finally, we highlight the reasonable expectations from the field and the challenges lying ahead in the creation of complex and evolvable matter.

Unveiling the Synergy of Coupled Gold Nanoparticles and J-Aggregates in Plexcitonic Systems for Enhanced Photochemical Applications.

Plexcitonic systems based on metal nanostructures and molecular J-aggregates offer an excellent opportunity to explore the intriguing interplay between plasmonic excitations and excitons, offering unique insights into light-matter interactions at the nanoscale. Their potential applications in photocatalysis have prompted a growing interest in both their synthesis and the analysis of their properties. However, in order to construct a high-performing system, it is essential to ensure chemical and spectral compatibility between both components. We present the results of a study into a hybrid system, achieved through the coupling of gold nanobipyramids with organic molecules, and demonstrate the strengthened photochemical properties of such a system in comparison with purely J-aggregates. Our analysis includes the absorbance and photoluminescence characterization of the system, revealing the remarkable plexcitonic interaction and pronounced coupling effect. The absorbance spectroscopy of the hybrid systems enabled the investigation of the coupling strength (g). Additionally, the photoluminescence response of the J-aggregates and coupled systems reveals the impact of the coupling regime. Utilizing fluorescence lifetime imaging microscopy, we established how the photoluminescence lifetime components of the J-aggregates are affected within the plexcitonic system. Finally, to assess the photodegradation of J-aggregates and plexcitonic systems, we conducted a comparative analysis. Our findings reveal that plasmon-enhanced interactions lead to improved photostability in hybrid systems.

Electrostatically Directed Long-Range Self-Assembly of Nucleotides with Cationic Nanoparticles To Form Multifunctional Bioplasmonic Networks.

Precise control over interparticle interactions is essential to retain the functions of individual components in a self-assembled superstructure. Here, we report the design of a multifunctional bioplasmonic network via an electrostatically directed self-assembly process involving adenosine 5'-triphosphate (ATP). The present study unveils the ability of ATP to undergo a long-range self-assembly in the presence of cations and gold nanoparticles (AuNP). Modelling and NMR studies gave a qualitative insight into the major interactions driving the bioplasmonic network formation. ATP-Ca2+ coordination helps in regulating the electrostatic interaction, which is crucial in transforming an uncontrolled precipitation into a kinetically controlled aggregation process. Remarkably, ATP and AuNP retained their inherent properties in the multifunctional bioplasmonic network. The generality of electrostatically directed self-assembly process was extended to different nucleotide-nanoparticle systems.

Temporal Changes in Interparticle Interactions Drive the Formation of Transiently Stable Nanoparticle Precipitates.

We demonstrate the power of fine-tuned interparticle interactions, emanating from appropriately functionalized surfaces, in creating self-assembled structures that show a transient switching between completely precipitated and redispersed stages of nanoparticles (NPs). The pH-dependent temporal changes in the strength of electrostatic interactions are explored to unveil a transient self-assembly response in plasmonic NPs. The assembly process was triggered by the electrostatic attraction between positively charged gold NPs (AuNPs) and an aggregating agent, ethylenediaminetetraacetic acid (EDTA). The autonomous changes in the pH and ionic strength of the solution, under the influence of atmospheric CO2, weaken the aggregating ability of EDTA and initiate the complete disassembly of [+] AuNP-EDTA precipitates. The use of a nondestructive mode of autonomous disassembly helped in achieving some of the desirable feats in the field of transient self-assembly such as easy removal of waste, formation of a transiently stable precipitate state, and negligible dampness in redispersion. The chemical strategy adopted in the present work, to introduce transientness, can act as a generic tool in creating the next generation of complex matter.

Electrostatically Driven Resonance Energy Transfer in an All-Quantum Dot Based Donor-Acceptor System.

Demonstration of fundamental photophysical properties in environmentally friendly quantum dots (QDs) is essential to realize their practical use in various light harvesting applications. We accomplish here an efficient light induced resonance energy transfer in all-QD based donor-acceptor system in water, deprived of any commonly used organic dye component. Our nanohybrid system comprises surface engineered indium phosphide/zinc sulfide (InP/ZnS) QD as the donor, and copper indium sulfide/zinc sulfide (CIS/ZnS) QD as the acceptor. The electrostatic attraction between oppositely charged QDs is vital in achieving a strong ground state complexation in the [-] InP/ZnS:::[+] CIS/ZnS QD nanohybrid. A nonlinear Stern-Volmer plot confirms the involvement of both static and dynamic components in the PL quenching of InP/ZnS QD by CIS/ZnS QD. Moreover, a temporal evolution of resonance energy transfer is realized in the solid state as well, which can improve the potential of such "all-green QD" based nanohybrid systems for device level studies.

Multicolor Luminescent Patterning via Photoregulation of Electron and Energy Transfer Processes in Quantum Dots.

Ability to create high-contrast multicolor luminescent patterns is essential to realize the full potential of quantum dots (QDs) in display technologies. The idea of using a nonemissive state is adopted in the present work to enhance the color-contrast of QD-based photopatterns. This is achieved at a multicolor level by the photoregulation of electron and energy transfer processes in a single QD nanohybrid film, composed of one QD donor and two dye acceptors. The dominance of photoinduced electron transfer over the energy transfer process generates a nonluminescent QD nanohybrid film, which provides the black background for multicolor patterning. The superior photostability of QDs over dyes is used for the photoregulation of electron and energy transfer processes. Selective photodegradation of electron acceptor dye triggered the onset of the energy transfer process, thereby imparting a luminescent color to the QD nanohybrid film. Further, a controlled photoregulation of energy transfer process paved the way for multicolor patterning.

Does navigated patellar resurfacing in total knee arthroplasty result in proper bone cut, motion and clinical outcomes?

BACKGROUND: In total knee arthroplasty with patellar resurfacing, patellar bone preparation, component positioning and motion assessments are still not navigated. Only femoral/tibial component positioning is supported by computer-assistance. The aim of this study was to verify, in-vivo, whether knee surgical navigation extended to patellar resurfacing, by original instrumentation and procedures for patellar-based tracking, could achieve accurate patella preparation in terms of original thickness restoration, bone cut orientation, and normal knee motion. METHODS: An additional navigation system for patellar data acquisition was used together with a standard navigation system for total knee arthroplasty in 20 patients. This supported the surgeon for patellar resurfacing via measurement of removed bone thickness, three-dimensional patellar cut orientations, and patello-femoral motion. Radiological and clinical examinations at 6 and 24-month follow-up were also performed. FINDINGS: The medio-lateral patellar-bone cut orientation was respectively 0.5° (standard deviation: 3.0°) and 1.4° (1.7°) lateral tilt, as measured via navigation and post-operatively on the Merchant x-ray view. The cranio-caudal orientation was 3.8° (7.2°) of flexion. The thickness variation between patellar pre- and post-implantation was 0.2 (1.3) mm. Immediately after implantation, patello-femoral as well as tibio-femoral kinematics was within the normality. Good radiological and clinical examinations at 6 and 24-month follow-up were also observed. INTERPRETATION: For the first time, the effect of patellar navigation for its resurfacing was assessed in-vivo during surgery, with very good results for thickness restoration, proper cut orientation, and normal knee motion. These results support the introduction of patella-related navigation-based surgical procedures for computer-assisted total knee arthroplasty.

Perception among Healthcare Professionals of the Use of Social Media in Translating Research Evidence into Clinical Practice in Mangalore.

INTRODUCTION: Social media has a potential to bring about major changes in the healthcare system. OBJECTIVE: To find out the pattern of use of social media among healthcare professionals (HCPs) and perception, facilitators, and barriers of using social media, to translate evidence into clinical practice. METHOD: We conducted a cross-sectional study among 196 HCPs of institutions attached to a university using a self-administered questionnaire. RESULT: 97.3% used social media; however, only 63.4% used it for research. YouTube was the most preferred media. Majority of people believed that social media enables wide range of evidence over the shorter span of time, poses a threat to privacy, and cannot replace face to face interaction. Perceived barriers were the privacy concern, unprofessional behavior, lack of reliability, and information overload. CONCLUSION: There is a need for the development of appropriate guidelines for sharing the research output among various stakeholders using social media.

Electrostatically driven resonance energy transfer in "cationic" biocompatible indium phosphide quantum dots.

Indium Phosphide Quantum Dots (InP QDs) have emerged as an alternative to toxic metal ion based QDs in nanobiotechnology. The ability to generate cationic surface charge, without compromising stability and biocompatibility, is essential in realizing the full potential of InP QDs in biological applications. We have addressed this challenge by developing a place exchange protocol for the preparation of cationic InP/ZnS QDs. The quaternary ammonium group provides the much required permanent positive charge and stability to InP/ZnS QDs in biofluids. The two important properties of QDs, namely bioimaging and light induced resonance energy transfer, are successfully demonstrated in cationic InP/ZnS QDs. The low cytotoxicity and stable photoluminescence of cationic InP/ZnS QDs inside cells make them ideal candidates as optical probes for cellular imaging. An efficient resonance energy transfer (E ∼ 60%) is observed, under physiological conditions, between the cationic InP/ZnS QD donor and anionic dye acceptor. A large bimolecular quenching constant along with a linear Stern-Volmer plot confirms the formation of a strong ground state complex between the cationic InP/ZnS QDs and the anionic dye. Control experiments prove the role of electrostatic attraction in driving the light induced interactions, which can rightfully form the basis for future nano-bio studies between cationic InP/ZnS QDs and anionic biomolecules.

Congenital pseudarthrosis of the clavicle: a report on 27 cases.

HYPOTHESIS: We aimed to report our experience in treating congenital pseudarthrosis of the clavicle (CPC). MATERIALS AND METHODS: A retrospective search of the archive of our institute was performed; 27 cases (12 male and 15 female patients) affected by CPC were recorded. Among these patients, 19 underwent surgical intervention for cosmetic appearance between 1960 and 2015. Of 19 patients, 18 were treated by pseudarthrosis resection and stabilization with a Kirschner wire, whereas in 1 case, the osteosynthesis was performed with a plate. Iliac crest bone autograft was used in 15 patients, whereas 4 patients were treated with a fibular allograft. RESULTS: The mean follow-up period was 36.3 ± 49.1 months. Bone healing was achieved in 14 of 19 operated cases (74%); none of the patients had complaints regarding cosmetic abnormalities or unesthetic appearance. All the operated patients were pain free, range of motion was complete, and no other subjective anomalies were found. No vascular or neurologic complications were observed. However, the use of allograft was associated with high rates of nonunion in this case series (P = .037). CONCLUSION: CPC can be satisfactorily treated by K-wire fixation and autologous iliac crest bone grafting, which showed better results in terms of functional and cosmetic outcome.