Cation Exchange Protocols to Radiolabel Aqueous Stabilized ZnS, ZnSe, and CuFeS2 Nanocrystals with 64Cu for Dual Radio- and Photo-Thermal Therapy.

Here, cation exchange (CE) reactions are exploited to radiolabel ZnSe, ZnS, and CuFeS2 metal chalcogenide nanocrystals (NCs) with 64Cu. The CE protocol requires one simple step, to mix the water-soluble NCs with a 64Cu solution, in the presence of vitamin C used to reduce Cu(II) to Cu(I). Given the quantitative cation replacement on the NCs, a high radiochemical yield, up to 99%, is reached. Also, provided that there is no free 64Cu, no purification step is needed, making the protocol easily translatable to the clinic. A unique aspect of the approach is the achievement of an unprecedentedly high specific activity: by exploiting a volumetric CE, the strategy enables to concentrate a large dose of 64Cu (18.5 MBq) in a small NC dose (0.18 µg), reaching a specific activity of 103 TBq g-1. Finally, the characteristic dielectric resonance peak, still present for the radiolabeled 64Cu:CuFeS2 NCs after the partial-CE reaction, enables the generation of heat under clinical laser exposure (1 W cm-2). The synergic toxicity of photo-ablation and 64Cu ionization is here proven on glioblastoma and epidermoid carcinoma tumor cells, while no intrinsic cytotoxicity is seen from the NC dose employed for these dual experiments.

The Many "Facets" of Halide Ions in the Chemistry of Colloidal Inorganic Nanocrystals.

Over the years, scientists have identified various synthetic "handles" while developing wet chemical protocols for achieving a high level of shape and compositional complexity in colloidal nanomaterials. Halide ions have emerged as one such handle which serve as important surface active species that regulate nanocrystal (NC) growth and concomitant physicochemical properties. Halide ions affect the NC growth kinetics through several means, including selective binding on crystal facets, complexation with the precursors, and oxidative etching. On the other hand, their presence on the surfaces of semiconducting NCs stimulates interesting changes in the intrinsic electronic structure and interparticle communication in the NC solids eventually assembled from them. Then again, halide ions also induce optoelectronic tunability in NCs where they form part of the core, through sheer composition variation. In this review, we describe these roles of halide ions in the growth of nanostructures and the physical changes introduced by them and thereafter demonstrate the commonality of these effects across different classes of nanomaterials.

Localized Surface Plasmon Resonance in Semiconductor Nanocrystals.

Localized surface plasmon resonance (LSPR) in semiconductor nanocrystals (NCs) that results in resonant absorption, scattering, and near field enhancement around the NC can be tuned across a wide optical spectral range from visible to far-infrared by synthetically varying doping level, and post synthetically via chemical oxidation and reduction, photochemical control, and electrochemical control. In this review, we will discuss the fundamental electromagnetic dynamics governing light matter interaction in plasmonic semiconductor NCs and the realization of various distinctive physical properties made possible by the advancement of colloidal synthesis routes to such NCs. Here, we will illustrate how free carrier dielectric properties are induced in various semiconductor materials including metal oxides, metal chalcogenides, metal nitrides, silicon, and other materials. We will highlight the applicability and limitations of the Drude model as applied to semiconductors considering the complex band structures and crystal structures that predominate and quantum effects that emerge at nonclassical sizes. We will also emphasize the impact of dopant hybridization with bands of the host lattice as well as the interplay of shape and crystal structure in determining the LSPR characteristics of semiconductor NCs. To illustrate the discussion regarding both physical and synthetic aspects of LSPR-active NCs, we will focus on metal oxides with substantial consideration also of copper chalcogenide NCs, with select examples drawn from the literature on other doped semiconductor materials. Furthermore, we will discuss the promise that LSPR in doped semiconductor NCs holds for a wide range of applications such as infrared spectroscopy, energy-saving technologies like smart windows and waste heat management, biomedical applications including therapy and imaging, and optical applications like two photon upconversion, enhanced luminesence, and infrared metasurfaces.

Spectrally tunable infrared plasmonic F,Sn:In2O3 nanocrystal cubes.

A synthetic challenge in faceted metal oxide nanocrystals (NCs) is realizing tunable localized surface plasmon resonance (LSPR) near-field response in the infrared (IR). Cube-shaped nanoparticles of noble metals exhibit LSPR spectral tunability limited to visible spectral range. Here, we describe the colloidal synthesis of fluorine, tin codoped indium oxide (F,Sn:In2O3) NC cubes with tunable IR range LSPR for around 10 nm particle sizes. Free carrier concentration is tuned through controlled Sn dopant incorporation, where Sn is an aliovalent n-type dopant in the In2O3 lattice. F shapes the NC morphology into cubes by functioning as a surfactant on the {100} crystallographic facets. Cube shaped F,Sn:In2O3 NCs exhibit narrow, shape-dependent multimodal LSPR due to corner, edge, and face centered modes. Monolayer NC arrays are fabricated through a liquid-air interface assembly, further demonstrating tunable LSPR response as NC film nanocavities that can heighten near-field enhancement (NFE). The tunable F,Sn:In2O3 NC near-field is coupled with PbS quantum dots, via the Purcell effect. The detuning frequency between the nanocavity and exciton is varied, resulting in IR near-field dependent enhanced exciton lifetime decay. LSPR near-field tunability is directly visualized through IR range scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS). STEM-EELS mapping of the spatially confined near-field in the F,Sn:In2O3 NC array interparticle gap demonstrates elevated NFE tunability in the arrays.

Colloidal ReO3 Nanocrystals: Extra Re d-Electron Instigating a Plasmonic Response.

Rhenium (+6) oxide (ReO3) is metallic in nature, which means it can sustain localized surface plasmon resonance (LSPR) in its nanocrystalline form. Herein, we describe the colloidal synthesis of nanocrystals (NCs) of this compound, through a hot-injection route entailing the reduction of rhenium (+7) oxide with a long chain ether. This synthetic protocol is fundamentally different from the more widely employed nucleophilic lysing of metal alkylcarboxylates for other metal oxide NCs. Owing to this difference, the NC surfaces are populated by ether molecules through an L-type coordination along with covalently bound (X-type) hydroxyl moieties, which enables easy switching from nonpolar to polar solvents without resorting to cumbersome ligand exchange procedures. These as-synthesized NCs exhibit absorption bands at around 590 nm (∼2.1 eV) and 410 nm (∼3 eV), which were respectively ascribed to their LSPR and interband absorptions by Mie theory simulations and Drude modeling. The LSPR response arises from the oscillation of free electron density created by the extra Re d-electron per ReO3 unit in the NC lattice, which resides in the conduction band. Further, the LSPR contribution facilitates the observation of dynamic optical modulation of the NC films as they undergo progressive electrochemical charging via ion (de)insertion. Ion (de)insertion leads to distinct dynamic optical signatures, and these changes are reversible in a wide potential range depending on the choice of the ion (lithium or tetrabutylammonium). Nanostructuring in ReO3 and the description of the associated plasmonic properties of these NCs made this optical modulation feasible, which were hitherto not reported for the bulk material. We envisage that the synthetic protocol described here will facilitate further exploration of such applications and fundamental studies of these plasmonic NCs.

Quasi-Static Resonances in the Visible Spectrum from All-Dielectric Intermediate Band Semiconductor Nanocrystals.

The quest for materials with metal-like properties as alternatives to noble metals is an intense area of research that is set to lead to dramatic improvements in technologies based on plasmonics. Here, we present intermediate band (IB) semiconductor nanocrystals (NCs) as a class of all-dielectric nanomaterials providing quasi-static optical resonances. We show that IB NCs can display a negative permittivity in a broad range of visible wavelengths, enabling a metal-like optical response despite the absence of free carriers in the NC ground state. Using a combination of spectroscopy measurements and ab initio calculations, we hereby provide a theoretical model for both the linear and nonlinear optical properties of chalcopyrite CuFeS2 NCs, as a case study of IB semiconductor nanomaterials. Our results rationalize the high performance of IB nanomaterials as photothermal agents and suggest the use of IB semiconductors as alternatives to noble metals for technologies based on plasmonic materials.

Colloidal Monolayer ß-In2Se3 Nanosheets with High Photoresponsivity.

We report a low-temperature colloidal synthesis of single-layer, five-atom-thick, ß-In2Se3 nanosheets with lateral sizes tunable from ∼300 to ∼900 nm, using short aminonitriles (dicyandiamide or cyanamide) as shape controlling agents. The phase and the monolayer nature of the nanosheets were ascertained by analyzing the intensity ratio between two diffraction peaks from two-dimensional slabs of the various phases, determined by diffraction simulations. These findings were further backed-up by comparing and fitting the experimental X-ray diffraction pattern with Debye formula simulated patterns and with side-view high-resolution transmission electron microscopy imaging and simulation. The ß-In2Se3 nanosheets were found to be indirect band gap semiconductors (Eg = 1.55 eV), and single nanosheet photodetectors demonstrated high photoresponsivity and fast response times.

Selective cation exchange in the core region of Cu2-xSe/Cu2-xS core/shell nanocrystals.

We studied cation exchange (CE) in core/shell Cu2-xSe/Cu2-xS nanorods with two cations, Ag(+) and Hg(2+), which are known to induce rapid exchange within metal chalcogenide nanocrystals (NCs) at room temperature. At the initial stage of the reaction, the guest ions diffused through the Cu2-xS shell and reached the Cu2-xSe core, replacing first Cu(+) ions within the latter region. These experiments prove that CE in copper chalcogenide NCs is facilitated by the high diffusivity of guest cations in the lattice, such that they can probe the whole host structure and identify the preferred regions where to initiate the exchange. For both guest ions, CE is thermodynamically driven as it aims for the formation of the chalcogen phase characterized by the lower solubility under the specific reaction conditions.

Hollow and concave nanoparticles via preferential oxidation of the core in colloidal core/shell nanocrystals.

Hollow and concave nanocrystals find applications in many fields, and their fabrication can follow different possible mechanisms. We report a new route to these nanostructures that exploits the oxidation of Cu(2-x)Se/Cu(2-x)S core/shell nanocrystals with various etchants. Even though the Cu(2-x)Se core is encased in a thick Cu(2-x)S shell, the initial effect of oxidation is the creation of a void in the core. This is rationalized in terms of diffusion of Cu(+) ions and electrons from the core to the shell (and from there to the solution). Differently from the classical Kirkendall effect, which entails an imbalance between in-diffusion and out-diffusion of two different species across an interface, the present mechanism can be considered as a limiting case of such effect and is triggered by the stronger tendency of Cu(2-x)Se over Cu(2-x)S toward oxidation and by fast Cu(+) diffusion in copper chalcogenides. As the oxidation progresses, expansion of the inner void erodes the entire Cu(2-x)Se core, accompanied by etching and partial collapse of the shell, yielding Cu(2-x)S(y)Se(1-y) concave particles.

Copper sulfide nanocrystals with tunable composition by reduction of covellite nanocrystals with Cu+ ions.

Platelet-shaped copper sulfide nanocrystals (NCs) with tunable Cu stoichiometry were prepared from Cu-rich covellite (Cu1.1S) nanoplates through their reaction with a Cu(I) complex ([Cu(CH3CN)4]PF6) at room temperature. Starting from a common sample, by this approach it is possible to access a range of compositions in these NCs, varying from Cu1.1S up to Cu2S, each characterized by a different optical response: from the metallic covellite, with a high density of free carriers and strong localized surface plasmon resonance (LSPR), up to Cu2S NCs with no LSPR. In all these NCs the valency of Cu in the lattice stays always close to +1, while the average -1 valency of S in covellite gradually evolves to -2 with increasing Cu content; i.e., sulfur is progressively reduced. The addition of copper to the starting covellite NCs is similar to the intercalation of metal species in layered transition metal dichalcogenides (TMDCs); i.e., the chalcogen-chalcogen bonds holding the layers are progressively broken to make room for the intercalated metals, while their overall anion sublattice does not change much. However, differently from the TMDCs, the intercalation in covellite NCs is sustained by a change in the redox state of the anion framework. Furthermore, the amount of Cu incorporated in the NCs upon reaction is associated with the formation of an equimolar amount of Cu(II) species in solution. Therefore, the reaction scheme can be written as: Cu1.1S + 2γCu(I) → Cu1.1+γS + γCu(II).

Surgical Triumph Over Metatarsal Osteosarcoma: A Rare Case Report Revealing Diagnostic Challenges and Successful Management.

Osteosarcoma of the foot is exceedingly uncommon, and as a result, very little is known about patient and tumor characteristics. In addition, the prognosis may be grim due to delayed presentation and misdiagnosis. A delayed diagnosis of osteosarcoma, regardless of location, may not only reduce long-term survival but also modify the treatment plan, resulting in less favorable functional and cosmetic outcomes. Here we report the diagnostic and therapeutic challenges associated with chondroblastic osteosarcoma involving the metatarsal bone of the foot in a 47-year-old woman treated with wide local excision with right second metatarsectomy and non-vascularized fibular graft reconstruction along with adjuvant chemotherapy.

Harnessing the Forgotten Triangles of the Neck for Lingual Artery Ligation in Glossectomies: A Technical Report.

Various geometric structures, such as numerous triangles, are prevalent in the neck. Despite the fact that many of the neck's anatomical triangles have been well documented, others have been almost forgotten about. The repertoire of head and neck cancer surgeons should include an in-depth understanding of these forgotten triangles. This article seeks to contribute valuable information to the existing scientific literature by shedding light on these neglected triangles, which have significant surgical relevance. In this technical report, we provide a detailed description of a technique that employs these neglected triangles to ligate the lingual artery during glossectomies for tongue cancer.

The External Jugular Vein Cut-Down Method for Chemoport Insertion from a Tertiary Cancer Treatment Center in Central India: A Prospective Study.

INTRODUCTION: In the realm of oncology, the development of TIVAD (chemoport) has been a blessing for cancer patients, freeing them from having to undergo numerous recurrent venepunctures throughout their treatment. The External Jugular Vein cut-down has been the standard procedure for administering chemotherapy to cancer patients at our institution. Here, we discuss our experience with the External Jugular Vein cut-down Chemoport Insertion Technique and the outcomes it produced. MATERIALS AND METHODS: We performed a prospective observational study and included all patients who underwent the open External Jugular Vein cut-down technique of Chemoport Insertion from January 2019 to January 2022 in the Department of Surgical Oncology at our hospital. RESULTS: Out of 136 patients, 3 (2.2%) had failed external jugular vein (EJV) cannulation, and alternative access (Internal Jugular Vein) was chosen for cannulation. The most common indication for chemoport insertion in our study was carcinoma of the breast, around 72.93% (97/133), and hence the majority of patients were females, about 84.21% (112/133). Only 18.04% (24/133) were male patients. The age distribution ranged from 2 years to 84 years. Out of 133 patients, complications were observed in 14 patients (10.52%). Around 6 patients (4.5%) had problems with catheter blockage after one cycle of chemotherapy. 4 patients (3%) had port infections at the chamber region (pectoral region). 3 patients (2.2%) had catheter tip displacement into the brachiocephalic vein. 1 patient (0.75%) had extravasation of chemotherapy. CONCLUSION: In conclusion, our study demonstrates that the External Jugular Vein cut-down technique offers several advantages in the realm of oncology, as it is a safe, efficient, and straightforward technique for chemoport insertion. With its minimal learning curve and simplicity, this technique represents a favorable initial option for successfully implanting chemoports in cancer patients. Further research and comparative studies are needed to validate and further explore the benefits of this technique in diverse patient populations and healthcare settings.

NIPEC with Single-Dose Intraperitoneal Cisplatin and Paclitaxel in Stage III Epithelial Ovarian Cancer.

Sanjay M. DesaiObjectives Epithelial ovarian cancer (EOC) is a heterogeneous, essentially peritoneal disease. Standard treatment consists of staging, cytoreductive surgery (CRS), and adjuvant chemotherapy. In this study, we intended to assess the effectiveness of single-dose intraperitoneal (IP) chemotherapy in optimally debulked advanced EOC patients. Materials and Methods A prospective randomized study of 87 patients with advanced EOC was done from January 2017 to May 2021 in a tertiary care center. Patients who underwent primary and interval cytoreduction received a single dose of IP chemotherapy for 24 hours after being divided into four groups: group A, IP cisplatin; group B, IP paclitaxel; group C, IP paclitaxel and cisplatin; and group D, saline. Pre- and postperitoneal IP cytology was assessed along with possible complications. Statistical Analysis Logistic regression analysis was used to assess for intergroup significance in cytology and complications. Kaplan-Meir analysis was done to assess disease-free survival (DFS). Results Of 87 patients, 17.2% of patients had FIGO stage IIIA, 47.2% had IIIB, and 35.6% had IIIC. Also, 22 (25.3%) patients were in group A (cisplatin), 22 (25.3%) patients in group B (paclitaxel), 23 (26.4%) in group C (cisplatin and paclitaxel), and 20 (23%) in group D (saline). Cytology samples taken during staging laparotomy were positive, and 48 hours post-IP chemotherapy, 2 (9%) of 22 samples in cisplatin group and 14 (70%) of 20 samples in saline group were positive; all of the post-IP samples in groups B and C were negative. No major morbidity was noted. In our study, DFS in saline group was 15 months, while in IP chemotherapy group it was 28 months and was statistically significant based log-rank test. However, there was no significant difference in DFS between different IP chemotherapy groups. Conclusion Complete or optimal CRS in advanced EOC does have a possibility of microscopic peritoneal residue. Adjuvant locoregional strategies should be considered to prolong DFS. Single-dose normothermic IP chemotherapy can be offered to the patients with minimal morbidity, and its prognostic benefits are comparable to hyperthermic IP chemotherapy. Future clinical trials are required to validate these protocols.

Beyond Traditional Approaches: A Pilot Study Exploring the Role of Injection Mitomycin C on the Surgical Resection Bed in Oral Cancer Treatment.

Background Oral cavity cancer ranks sixth among all cancers worldwide. India has the most oral cancer cases and accounts for one-third of the global oral cancer burden. Oral cavity cancer is known to be associated with an elevated likelihood of locoregional recurrences, which account for the bulk of post-surgery and radiotherapy treatment failures. Mitomycin C (MMC) is an antineoplastic and antibiotic agent that is administered topically rather than intravenously to treat bladder and intraperitoneal tumors to avoid recurrences. This study aimed to investigate the use of injection MMC as a local application on surgical resection beds for patients undergoing surgery for oral cancer and to assess its efficacy in preventing regional recurrences. Methodology In this prospective, interventional, pilot study, patients were assigned randomly to two groups using simple randomization. Group A involved the application of two gauze pieces soaked with MMC injection. Group B involved the application of two gauze pieces soaked with a 10% betadine solution. During the pectoralis major myocutaneous flap harvest procedure for reconstruction, two gauze pieces soaked with either injection MMC solution (20 mg MMC in 20 mL of 0.9% normal saline) or 10% betadine solution were placed on the surgical resection bed for a 45-minute contact period. Patients were evaluated daily in the postoperative period for local complications. Regular follow-up visits were scheduled for 15 months of follow-up. Results After exclusions at various phases, the final analysis included 50 patients in Group A and 50 patients in Group B. Minor complications, specifically blackening of the skin flap in the neck resulting in surgical site infections, were observed in 16% (eight patients) of the MMC group and in 6% (three patients) of the betadine group (p = 0.1997) patients. In the MMC group, two (4%) patients experienced locoregional recurrences at three months, four (8%) patients at six months, six (12%) patients at nine months, eight (16%) patients at 12 months, and 10 (20%) patients at 15 months of follow-up. In contrast, locoregional recurrences occurred in two (4%) patients in the betadine group at three months, six (12%) patients at six months, nine (18%) patients at nine months, 12 (24%) patients at 12 months, and 15 (30%) patients at 15 months. Although the difference in locoregional recurrences between the two groups was not statistically significant, there was a trend of decreasing locoregional recurrences in the MMC group relative to the betadine group as the duration of follow-up increased. In the subgroup analysis of patients with pathological extranodal extension (ENE), only 10 of 18 patients with ENE in Group A (55.55%) experienced a recurrence, whereas all 12 patients with ENE in Group B (100%) experienced a recurrence within the same time frame. This difference in locoregional recurrence rates between the two groups was statistically significant, with a p-value of 0.0100. Conclusions Our study demonstrated that the local administration of MMC on surgical resection beds may lower the risk of locoregional recurrences in patients with oral cancer, especially those with ENE. These findings contribute to the ongoing efforts to enhance treatment strategies and patient outcomes for this challenging malignancy.

Comparison of Functional and Survival Outcomes in Pedicled and Microsurgical Flap Reconstruction for Near-Total and Total Glossectomies.

Introduction: Patients with advanced carcinoma tongue end up with near-total/total glossectomy (NTG/TG). We intended to compare functional, oncological, and survival outcomes of patients undergoing pedicled and microsurgical flap reconstruction in NTG/TG patients at our hospital. Methodology: A prospective study was conducted for 7 years on 91 patients with carcinoma tongue who underwent NTG/TG at our institute. Patients underwent anterolateral thigh (ALT), free radial artery forearm flap (FRAFF), and pectoralis major myocutaneous (PMMC) flap reconstruction and were followed up for immediate complications and functional outcomes for speech, swallowing, and decannulation after completion of adjuvant treatment and then for survival rates for a period of 60 months and statistically analysed with log rank test and Fisher's exact test for correlation. Results: Ninety-one (42.85%) patients underwent NTG, while 57.14% underwent TG. 85% of patients had >5 mm margin, 14% had ≤ of 5 mm, and none were positive. 57% of patients did not have postoperative complications and 10% underwent re-exploration. During follow-up, 85.7% of patients were able to take orally: 52% soft diet and 32% liquid diet. Multivariate analysis of individual flaps, swallowing, and speech intelligibility values were significant. After 5 years of postadjuvant therapy, there was 76% overall survival, 11% local recurrence and 12% had regional recurrence. Discussion: Morbidity and functional outcome depends on the extent of resection. PMMC flaps can be done on lack of expertise. FRAFF has better functional outcomes owing to pliability of flap. ALT and other bulky flaps require expertise and are prone to flap-related complications. Planning of reconstruction should be based on the defect size together with counseling of patients regarding the risk of complications and delay in adjuvant therapy.

Outcome Evaluation of Mandibular Pull-Through Approach for Glossectomies.

Patients with advanced carcinoma tongue in the Indian subcontinent have an additional component of submucosal fibrosis (SMF) due to chewing of betel. We intend to evaluate  mandibular pull-through approach for total or near-total glossectomy and assessed its functional and survival outcome. Prospective study of 77 patients with carcinoma tongue, who underwent total or near-total glossectomy at our institute, were assessed retrospectively. All the patients who underwent glossecomy through mandibular pull through approach with pedicled or free flap reconstruction were assessed for functional and survival outcomes. Of the 77 patients, 45 (58.44%) patients underwent total glossectomy, while 32 (41.55%) patients near-total glossectomy, 61 (79.22%) cases had operative time ≤ 30 min, 69 (89.61%) patients had margins of > 5 mm, and none of the margins were involved. Flaps were reconstructed with 42 (54.54%) PMMC, 24 (31.16%) FRAFF, and 11 (14.28%) ALT. Five (6.49%) patients had surgical site infections, 6 patients each had to undergo re-explorations and partial flap loss, 7 patients had oro-cutaneous fistula, while 53 (68.83%) patients had no complications/osteoradionecrosis. A total of 94% of patients underwent decannulation, 92% of patients got discharged, and 89% got NG tube removed within 21 POD. Forty patients had reasonably good speech. On the long-term follow-up, 9% of the patients developed local recurrence and 11% of patients had regional/lymph node recurrence. Mandibular pull-through approach had the advantages of good accessibility to the tumour with the least mutilating techniques with shorter operation time, lower rates of postoperative complications, and better aesthetics and based on available data, it is superior to the mandibular lip-spilt surgery for advanced tongue involving BOT and floor of mouth cancers when coupled with SMF surgeries for the Indian scenario.

New strategies for the enrichment of metallic single-walled carbon nanotubes.

Enrichment of metallic single-walled carbon nanotubes (SWNTs) has been accomplished by several means, including new extraction and synthetic procedures and by interaction with metal nanoparticles as well as electron donor molecules. In the presence of Fe(CO)5, the arc discharge method yields nearly pure metallic nanotubes. Fluorous chemistry involving the preferential diazotization of metallic SWNTs offers a good procedure of obtaining the pure metallic species. Interaction of gold or platinum nanoparticles as well as of electron-donor molecules such as aniline and tetrathiafulvalene (TTF) transform semiconducting SWNTs into metallic ones. Raman and electronic spectroscopies provide ideal means to monitor enrichment of metallic SWNTs.

Synthesis and Dual-Mode Electrochromism of Anisotropic Monoclinic Nb12O29 Colloidal Nanoplatelets.

Transition metal oxide nanocrystals with dual-mode electrochromism hold promise for smart windows enabling spectrally selective solar modulation. We have developed the colloidal synthesis of anisotropic monoclinic Nb12O29 nanoplatelets (NPLs) to investigate the dual-mode electrochromism of niobium oxide nanocrystals. The precursor for synthesizing NPLs was prepared by mixing NbCl5 and oleic acid to form a complex that was subsequently heated to form an oxide-like structure capped by oleic acid, denoted as niobium oxo cluster. By initiating the synthesis using niobium oxo clusters, preferred growth of NPLs over other polymorphs was observed. The structure of the synthesized NPLs was examined by X-ray diffraction in conjunction with simulations, revealing that the NPLs are monolayer monoclinic Nb12O29, thin in the [100] direction and extended along the b and c directions. Besides having monolayer thickness, NPLs show decreased intensity of Raman signal from Nb-O bonds with higher bond order when compared to bulk monoclinic Nb12O29, as interpreted by calculations. Progressive electrochemical reduction of NPL films led to absorbance in the near-infrared region (stage 1) followed by absorbance in both the visible and near-infrared regions (stage 2), thus exhibiting dual-mode electrochromism. The mechanisms underlying these two processes were distinguished electrochemically by cyclic voltammetry to determine the extent to which ion intercalation limits the kinetics, and by verifying the presence of localized electrons following ion intercalation using X-ray photoelectron spectroscopy. Both results support that the near-infrared absorption results from capacitive charging, and the onset of visible absorption in the second stage is caused by ion intercalation.

Stable dispersions of metal oxide nanowires and nanoparticles in water, dimethylformamide and toluene.

In view of the important need to generate well-dispersed inorganic nanostructures in various solvents, we have explored the dispersion of nanostructures of metal oxides such as TiO2, Fe3O4 and ZnO in solvents of differing polarity in the presence of several surfactants. The solvents used are water, dimethylformamide (DMF) and toluene. The surfactant-solvent combinations yielding the best dispersions are reported alongwith some of the characteristics of the nanostructures in the dispersions. The surfactants which dispersed TiO2 nanowires in water were polyethylene oxide (PEO), Triton X-100 (TX-100), polyvinyl alcohol (PVA) and sodium bis(2-ethylhexyl) sulphosuccinate (AOT). TiO, nanoparticles could also be dispersed with AOT and PEO in water, and with AOT in toluene. In DMF, PVA, PEO and TX-100 were found to be effective, while in toluene, only AOT gave good dispersions. Fe3O4 nanoparticles were held for long periods of time in water by PEO, AOT, PVA and polyethylene glycol (PEG), and by AOT in toluene. In the case of ZnO nanowires, the best surfactant-solvent combinations were found to be, PEO, sodium dodecyl sulphate (SDS) and AOT in water and AOT, PEG, PVA, PEO and TX-100 in DMF. In toluene, stable dispersions of ZnO nanowires were obtained with PEO. We have also been able to disperse oxide nanostructures in non-polar solvents by employing a hydrophobic silane coating on the surface.