Nanoscale self-assembly: concepts, applications and challenges.

Self-assembly offers unique possibilities for fabricating nanostructures, with different morphologies and properties, typically from vapour or liquid phase precursors. Molecular units, nanoparticles, biological molecules and other discrete elements can spontaneously organise or form via interactions at the nanoscale. Currently, nanoscale self-assembly finds applications in a wide variety of areas including carbon nanomaterials and semiconductor nanowires, semiconductor heterojunctions and superlattices, the deposition of quantum dots, drug delivery, such as mRNA-based vaccines, and modern integrated circuits and nanoelectronics, to name a few. Recent advancements in drug delivery, silicon nanoelectronics, lasers and nanotechnology in general, owing to nanoscale self-assembly, coupled with its versatility, simplicity and scalability, have highlighted its importance and potential for fabricating more complex nanostructures with advanced functionalities in the future. This review aims to provide readers with concise information about the basic concepts of nanoscale self-assembly, its applications to date, and future outlook. First, an overview of various self-assembly techniques such as vapour deposition, colloidal growth, molecular self-assembly and directed self-assembly/hybrid approaches are discussed. Applications in diverse fields involving specific examples of nanoscale self-assembly then highlight the state of the art and finally, the future outlook for nanoscale self-assembly and potential for more complex nanomaterial assemblies in the future as technological functionality increases.

Evaluation of macular perfusion in eyes with proliferative diabetic retinopathy using optical coherence tomography - Angiography following panretinal photocoagulation.

AIM: The aim of this study is to evaluate the effect of panretinal photocoagulation (PRP) on macular perfusion using optical coherence tomography-angiography (OCT-A) in eyes with proliferative diabetic retinopathy (PDR) by assessing the vessel density (VD) and the size of the foveal avascular zone (FAZ) of the superficial capillary plexus (SCP) and the deep capillary plexus (DCP), before and after PRP. SETTINGS AND DESIGN: Prospective interventional study. SUBJECTS AND METHODS: Twenty-nine eyes of 17 patients with PDR underwent a measurement of best-corrected visual acuity (BCVA) and were imaged using OCT and OCT-A at baseline and 6-months of follow-up. Patients received three sittings of PRP using frequency-doubled neodymium-doped yttrium aluminum garnet laser. STATISTICAL ANALYSIS USED: The OCT-A variables were analyzed using generalized estimating equations. RESULTS: BCVA was unchanged at 6-months follow-up (P = 0.09). FAZ of SCP and DCP (P = 0.28 and 0.89, respectively), VD at foveal SCP (P = 0.08), foveal DCP (P = 0.05), parafoveal SCP (P = 0.13), and parafoveal DCP (P = 0.07) showed no statistically significant difference at 6 months post PRP. CONCLUSIONS: OCT-A parameters were not significantly affected by PRP at 6-months follow-up indicating no alteration in macular perfusion. Further analyses with larger samples and longer duration are warranted to confirm our results.

Thin-section 3D Steady-State MRI in Optic Nerve Coloboma.

Optic nerve colobomas are congenital defects in the posterior globe of eye with typical funduscopic appearances. We report a two-year-old child suspected of morning glory disc anomaly who underwent thin-section 3D steady-state magnetic resonance imaging which showed characteristic findings of a tiny defect and discontinuity in the optic nerve head.

FIRST-IN-HUMAN CLINICAL STUDY TO INVESTIGATE THE EFFECTIVENESS AND SAFETY OF PARS PLANA VITRECTOMY SURGERY USING A NEW HYPERSONIC TECHNOLOGY.

PURPOSE: Investigate the effective performance and safety of a new hypersonic vitrector technology. METHODS: Postapproval, prospective, single-arm, noncomparative, open-label study at one clinical site in India. INDICATIONS: macular hole (9/20), vitreous hemorrhage (7/20), vitreomacular traction (3/20), and vitreomacular traction with pseudomacular hole (1/20). Safety endpoints included intraoperative and postoperative adverse events. Effective performance endpoints were surgeon-rated effectiveness, range of surgical time, and device settings. Other performance measures were preoperative and postoperative best-corrected visual acuity, slit-lamp and indirect ophthalmoscopy, applanation tonometry, color fundus photography, fundus fluorescein angiography, and spectral domain optical coherence tomography. RESULTS: Core vitreous removal (20/20 subjects), peripheral vitreous removal (18/20), and posterior vitreous detachment induction (13/15) surgeries were successfully completed. Total surgical time was 22.5 minutes to 106 minutes. Serious adverse events through 3 months were 2 device-associated retinal tears and detachment (one intraoperative) and one unrelated postoperative enlargement of macular hole with subretinal fluid. CONCLUSION: This first-in-human study suggests that this new hypersonic vitrector technology is a promising alternative to commercially available guillotine vitrectors. The hypersonic vitrector was effective in core vitreous removal in all cases. Larger-scale studies are required to expand on our initial findings for induction of a posterior vitreous detachment or peripheral vitrectomy.

Carbon Nanotube Assembly and Integration for Applications.

Carbon nanotubes (CNTs) have attracted significant interest due to their unique combination of properties including high mechanical strength, large aspect ratios, high surface area, distinct optical characteristics, high thermal and electrical conductivity, which make them suitable for a wide range of applications in areas from electronics (transistors, energy production and storage) to biotechnology (imaging, sensors, actuators and drug delivery) and other applications (displays, photonics, composites and multi-functional coatings/films). Controlled growth, assembly and integration of CNTs is essential for the practical realization of current and future nanotube applications. This review focuses on progress to date in the field of CNT assembly and integration for various applications. CNT synthesis based on arc-discharge, laser ablation and chemical vapor deposition (CVD) including details of tip-growth and base-growth models are first introduced. Advances in CNT structural control (chirality, diameter and junctions) using methods such as catalyst conditioning, cloning, seed-, and template-based growth are then explored in detail, followed by post-growth CNT purification techniques using selective surface chemistry, gel chromatography and density gradient centrifugation. Various assembly and integration techniques for multiple CNTs based on catalyst patterning, forest growth and composites are considered along with their alignment/placement onto different substrates using photolithography, transfer printing and different solution-based techniques such as inkjet printing, dielectrophoresis (DEP) and spin coating. Finally, some of the challenges in current and emerging applications of CNTs in fields such as energy storage, transistors, tissue engineering, drug delivery, electronic cryptographic keys and sensors are considered.

Adie's Tonic Pupil in Systemic Sclerosis: A Rare Association.

We report a rare association of Adie's tonic pupil in a patient with systemic sclerosis who was otherwise systemically stable. This paper is an effort to unravel whether the tonic pupil and systemic sclerosis are an association by chance (which may be the case) or systemic sclerosis is the source of the tonic pupil.

Ranibizumab as an adjunct to laser for macular edema secondary to branch retinal vein occlusion.

PURPOSE: To compare the safety, efficacy, and dosing regimen of intravitreal ranibizumab as an adjunct to laser therapy for the treatment of macular edema secondary to branch retinal vein occlusion (BRVO). MATERIALS AND METHODS: Thirty eyes of 30 patients of BRVO of at least 6 weeks duration were randomized into three groups: Group 1 received grid laser treatment alone, Group 2 received a single dose of intravitreal injection of ranibizumab (0.5 mg / 0.05 ml) followed by grid laser treatment on 7 th day following injection, while Group 3 received three loading doses of intravitreal ranibizumab at monthly interval (i.e. 0, 1, & 2 months) + standard laser treatment 7 days after the 1 st injection. Outcome measure noted at 6 months follow-up were the improvement in best-corrected visual acuity (BCVA) and central macular thickness (CMT). RESULTS: At 6 months follow-up, there was an average gain of 12 letters (P=0.05), 17.5 letters (P=0.05) and 19 letters (P=0.05) in groups 1, 2, and 3, respectively, with the decrease in CMT being 208.7 µm (P=0.05), 312.9 µm (P= 0.05) and 326.8 µm (P=0.05), respectively, in these groups. Gain in BCVA of more than 3 lines was noted in 1/10 patients in Group 1(10%) as compared to 3/10 (30%) and 4/10 (40%) patients in groups 2 and 3, respectively. CONCLUSION: The gain in BCVA and reduction in CMT were better with combination therapy (single- and triple- dose regimen) compared to grid laser alone. Single dose of intravitreal ranibizumab with grid laser seems to be an effective therapy.

Photodynamic monotherapy or combination treatment with intravitreal triamcinolone acetonide, bevacizumab or ranibizumab for choroidal neovascularization associated with pathological myopia.

This retrospective, interventional case series analyses treatment outcomes in eyes with choroidal neovascularization (CNV) secondary to pathological myopia, managed with photodynamic therapy, (PDT), (Group 1, N = 11), PDT and intravitreal triamcinolone acetonide (4 mg/0.1ml) (Group 2, N = 3), PDT and intravitreal anti-vascular endothelial growth factor (anti-VEGF) bevacizumab 1.25 mg/0.05 ml, ranibizumab 0.5 mg/0.05 ml and reduced-fluence PDT and intravitreal ranibizumab 0.5 mg/0.05 ml (Group 3, N=12). All the patients underwent PDT. Intravitreal injections were repeated as required. SPSS 14 software was used to evaluate the data. Wilcoxon signed ranks test was used to evaluate pre- and post-treatment vision. The Kruskal-Wallis test was used for comparison between the groups. All the groups were statistically comparable. All the eyes showed complete regression of CNV, with a minimum follow-up of six months. All groups had visual improvement; significantly in Group 3 ( p = 0.003). Combination PDT with anti-VEGF agents appeared to be efficacious in eyes with myopic CNV. However, a larger study with a longer follow-up is required to validate these results.

Combination photodynamic therapy and bevacizumab for choroidal neovascularization associated with toxoplasmosis.

A 14-year-old girl presenting with visual loss in both eyes was diagnosed to have healed toxoplasma retinochoroiditis in the right eye with active choroidal neovascularization (CNV) secondary to toxoplasmosis in the left. She underwent combination photodynamic therapy (PDT) and intravitreal bevacizumab as primary treatment. PDT was performed as per the 'Treatment of Age-related Macular Degeneration by Photodynamic therapy' study protocol and was followed by intravitreal bevacizumab after 2 days. CNV regressed at 8 weeks of follow-up and remained stable at 8 months of follow-up. The initial visual acuity improved from 20/120 to 20/30. Combination therapy with PDT and intravitreal bevacizumab appears to be effective in the treatment of CNV secondary to toxoplasma retinochoroiditis.