Fluorescent metal nanoclusters: prospects for photoinduced electron transfer and energy harvesting.

Research on noble metal nanoclusters (MNCs) (elements with filled electron d-bands) is progressing forward because of the extensive and extraordinary chemical, optical, and physical properties of these materials. Because of the ultrasmall size of the MNCs (typically within 1-3 nm), they can be applied in areas of nearly all possible scientific domains. The greatest advantage of MNCs is the tunability that can be imposed, not only on their structures, but also on their chemical, physical, and biological properties. Nowadays, MNCs are very effectively used as energy donors and acceptors under suitable conditions and hence act as energy harvesters in solar cells, semiconductors, and biomarkers. In addition, ultrafast photoinduced electron transfer (PET) can be practised using MNCs under various circumstances. Herein, we have focused on the energy harvesting phenomena of Au-, Ag-, and Cu-based MNCs and elaborated on different ways to apply them.

Hydrophobic Chain-Induced Conversion of Three-Dimensional Perovskite Nanocrystals to Gold Nanocluster-Grafted Two-Dimensional Platelets for Photoinduced Electron Transfer Substrate Formulation.

Considering the augmentation of new generation energy harvesting devices and applications of electron-hole separation therein, conversion of 3D cubic CsPbBr3 perovskite nanocrystals into 2D-platelets through ligand-ligand hydrophobic interactions has been conceived here. Cationic surfactants with various chain length coated the gold nanoclusters (AuNCs) that interact with oleic acid (OA) and oleylamine (OAm) coated 3D CsPbBr3 nanocrystals to disintegrate the crystallinity of the perovskites and reformation of AuNC-grafted 2D-platelets of unusually large size. The planar perovskite-derivatives act as an exciton donor to the embedded AuNCs through photoinduced electron transfer (PET). This process is controlled by the optimum surfactant chain length. Transient absorption spectroscopy shows that the fastest radical growth time (4 ps) was with the 14-carbon containing tail of the surfactant, followed by the 16-carbon (45 ps) and the 12-carbon (290 ps) ones. PET is administered by the energy gaps of the participating candidates that control the transition dynamics. Our findings can be a potential tool to develop metal nanocluster-based hybrid 2D perovskite-derived platelets for optoelectronic applications.

Photosensitization Dynamics of Stable Copper Nanoclusters inside the Aqueous Core of Reverse Micelles with Different Pool Sizes.

The perennial problem of instability of fluorescent copper nanoclusters (Cu NCs), stemming principally from aerial oxidation, has prevented their vivid usage in energy harvesting compared to the other metal NCs. However, replacement of the much expensive metal NCs with the cheaper Cu NCs is desirable if the functions are met with. Although thiolate protection of Cu NCs could bring some stability to them, appreciably decentlystable Cu NCs were produced inside the aqueous core of reverse micelles (RMs). However, this recent development has not been further explored on the photosensitization of the Cu NCs inside the RMs and their controlled modulation as energy antenna. Here we have synthesized stable Cu NCs inside the aqueous core of RMs with three different pool sizes and established photoinduced electron transfer (PET) to an electron acceptor. Considering the bulk quencher concentration, it appears that the extent of PET increases with decrease in the size of the aqueous core of RMs. However, calculating the effective concentration of the electron acceptor inside the RMs and considering the polarity of the microheterogeneous systems, it becomes clear that the extent of PET actually decreases with decrease in the size of the aqueous pool (w0, i.e., [H2O]/[AOT]) = 5-20) in the RMs. This proof of concept and the results are promising toward applications in PET-driven phenomena such as solar cells or batteries.

Clinical efficacy of periosteal pedicle graft with subepithelial connective tissue graft in gingival recession coverage.

INTRODUCTION: Correction of gingival recession (GR) involves eliminating the cause of recession and it often requires surgical correction. Subepithelial connective tissue graft (SCTG) technique by Langer and Langer provides excellent esthetics and is considered most predictable in obtaining marginal tissue recession coverage. However, the requirement of a second surgical procedure for harvesting CTG remote from planned site of recession coverage increases the chances of postoperative infection. There is also a limitation in the amount of graft that can be harvested and an increased operative time contributing to patient discomfort. MATERIALS AND METHODS: Overcoming these difficulties has become possible with the introduction of "periosteal pedicle graft" (PPG). The study is a split-mouth design where patients with bilateral, isolated GR defects were treated using two different surgical techniques, i.e., PPG versus the SCTG in obtaining GR coverage. The objective was to analyze the comparative amount of root coverage and the gain in width of attached gingiva achieved by both the techniques. RESULTS: All the clinical parameters evaluated were comparable between SCTG and PPG when recorded at 6 and 9 months posttreatment. CONCLUSION: Both techniques produced satisfactory and predictable results. PPG eliminated the need for the 2nd operative site, lesser intraoperative time, and hence, patient comfort was enhanced.

Comparative evaluation of anchorage reinforcement between orthodontic implants and conventional anchorage in orthodontic management of bimaxillary dentoalveolar protrusion.

BACKGROUND: Increased upper lip procumbency is commonly associated with maxillary dentoalveolar protrusion with the major goal of reducing maxillary dentoalveolar protrusion. The treatment plan usually includes extraction of the maxillary first premolars, followed by retraction of anterior teeth with maximum anchorage. Dental implants have been widely accepted as successful adjuncts for obtaining maximum anchorage in orthodontic treatment. METHODS: 50 subjects between the ages of 13 and 17 years having bimaxillary dentoalveolar protrusion were included in the study. The patients were divided into two groups. Both groups received treatment with 0.022″ MBT prescription preadjusted edgewise appliance system. In addition, subjects of Group 'I' received the Nance button and lingual arch as anchorage reinforcement in the upper and lower arches, respectively. Subjects of Group 'II' received self-drilling titanium OI for anchorage reinforcement. RESULTS: Significant retraction was achieved in all cases with good vertical control. Anchor loss was observed in both groups. Anchor loss was much higher in Group I compared to Group II, and an intergroup comparison for anchor loss was highly significant. CONCLUSION: Implants as anchorage, for en masse retraction, can be incorporated into orthodontic practice. The use of orthodontic implants for anchorage is a viable alternative to conventional molar anchorage.

Comparative evaluation of the marginal gingival epithelium in smokers and nonsmokers: a histomorphometric and immunohistochemical study.

Smoking is one of the strongest predictors of attachment and bone loss. Smokers demonstrate reduced inflammatory clinical signs, which could be due to local vasoconstriction and increased gingival epithelial thickness. The byproducts originating from tobacco oxidation modify the clinical characteristics and progression of periodontal disease. The aim of this study was to investigate the relationship between the thickness of marginal gingival oral epithelium, sulcular bleeding, and vascular caliber and density of the microvessels in smokers and nonsmokers with and without periodontitis and to better understand the role of smoking in relation to periodontal disease. One hundred twenty individuals were enrolled in this study and divided into four groups comprising 30 participants each. The clinical measurements carried out included probing depth, clinical attachment loss, and bleeding index, along with gingival biopsy specimens, which were subjected to immunohistochemical and histomorphometric analysis. Correlation of the clinical and histologic features revealed that smokers presented with fewer inflammatory signs, had fewer vascular elements in the subepithelial connective tissue layer, and showed a resultant increase in epithelial thickness irrespective of the presence of periodontitis. There was a mean increase of epithelial thickness of 181.3 µm (suprapapillary epithelial thickness [SET]) to 380.2 µm (maximal epithelial thickness [MET]) in smokers with periodontitis as compared to 157.4 µm (SET) to 325.3 µm (MET) in nonsmokers with periodontitis. The mean microvascular density in smokers with periodontitis was 325.4 per mm, which was found to be statistically significantly less than that of nonsmokers with periodontitis, who had a mean value of 412.13 per mm. The vessel caliber also was reduced in smokers, with a mean value ranging from 4.7 to 6.1 µm compared with a mean of 6.2 to 9.2 µm in nonsmokers, irrespective of the presence of periodontitis. Statistically significant differences were found in vascular density and thickness of gingival epithelium between smokers and nonsmokers with and without periodontitis. These differences may impact the progression of periodontal disease.

Periodontal pathogens in atheromatous plaque.

BACKGROUND: There has been increasing attention paid in recent years to the possibility that oral bacterial infection, particularly periodontal disease may influence the initiation and or progression of systemic diseases. These studies confirm the observation that heart disease is the most commonly found systemic condition in patients with periodontal disease. Moreover, the literature has also highlighted substantial evidence indicating the presence of Gram-negative periodontal pathogens in atheromatous plaques. AIM: This study intends to investigate the possible association between periodontal health and coronary artery disease by evaluating periodontal status, association between the periodontal plaque and coronary atheromatous plaques for presence of micro-organisms such as, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia. MATERIALS AND METHODS: A case-control study was designed with seven patients who had undergone coronary endarterectomy for cardiovascular disease and 28 controls. The periodontal examination for cases was performed 1 day before vascular surgery and the controls were clinically examined. The atheromatous plaque sample collected during endarterectomy and the intraoral plaque samples were subjected to polymerase chain reaction for identification of A. actinomycetemcomitans, P. gingivalis, P. intermedia and T. forsythia. RESULTS: The presence of periodontal bacteria DNA in coronary atheromatous plaques and sub-gingival plaque samples of the same patients was confirmed by this study. CONCLUSION A correlation was established between putative bacteria contributing to atheromatous plaques and species associated with periodontal disease. One particularly important study to be carried out is the investigation of a possible clinically meaningful reduction in coronary heart disease resulting from the prevention or treatment of periodontal disease.

Evaluation of serum ceruloplasmin in aggressive and chronic periodontitis patients.

BACKGROUND: Pro-inflammatory markers are seen to increase in inflammatory diseases like periodontitis. Detecting an increase in these markers is one of the diagnostic modality. One such marker, which can be detected, is the ceruloplasmin. Ceruloplasmin induces hypoxia and generates oxygen radicals at the site of aggressive periodontitis. It also causes a state of hypoferremia leading to increase in the natural resistance of the body. The aim of this study was to evaluate the serum levels of cerruloplasmin in both aggressive and chronic periodontitis patients. MATERIALS AND METHODS: Blood samples were collected from aggressive periodontitis patients (n = 20), chronic periodontitis patients (n = 20) and periodontally healthy patients (n = 20). The serum was extracted from all the blood samples and ceruloplasmin levels were spectroscopically evaluated through a new kinetic method, which used a norfloxacin based reagent. RESULTS: Serum ceruloplasmin levels were found to be significantly higher in aggressive periodontitis patients (P > 0.05) than in chronic periodontitis patients (P > 0.05) even though increase in the level of ceruloplasmin was found in chronic periodontitis. Periodontally healthy patients did not show increase in the levels of serum ceruloplasmin. The levels of serum ceruloplasmin also increased with the disease severity whose manifestations were increased bleeding on probing, increased pocket depth and increased attachment loss. CONCLUSION: Serum ceruloplasmin levels increased in both aggressive and chronic periodontitis patients, but more in aggressive periodontitis patients making it a potential marker for diagnosis of periodontitis.