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Organophosphorus pesticides, widely used as insecticides for crop protection, are classified as an extremely toxic class of chemical compounds by the World Health Organization (WHO). Organophosphorus pesticides show marked specificity for the enzyme acetylcholinesterase, and can cause irreversible harm to the nervous system. The excessive use of organophosphorus pesticides, specifically in developing countries, made WHO to impose a ban on certain organophosphorus pesticides being sold to the developing nations. WHO and the Food and Agriculture Organization of United Nations, in joint meetings on pesticide residues, have stressed the need to develop easy, rapid, and sensitive methods to detect the presence of organophosphorus pesticides in food and water. In this regard, a number of review articles have been published explaining a myriad of detection methods for organophosphorus pesticides. Among these, optical detection methods, using biological molecules as the recognition element, provide a number of advantages, such as, high sensitivity and selectivity, simple operation, fast response and cheap instrumentation, and can really prove to be an effective alternative to the time-consuming traditional methods in the current scenario. Therefore, in this review article, we have discussed the recent advances in the field of biosensors employing the optical detection of organophosphorus pesticides. Specifically, various biosensors developed, using enzymes acetylcholinesterase and organophosphate hydrolase, have been categorized on the basis of the material used for their fabrication. A systematic discussion of the working principles, analytical parameters, and advantages and disadvantages of the various biosensors, has been attempted, along with a future perspective, on the challenges and possible improvements in the field of optical detection of organophosphorus pesticides.

Although cyclodextrins have been extensively utilized in various branches of supramolecular chemistry due to their numerous attractive attributes, however, to achieve even advanced applications, they often need structural modification through substitutions of suitable functional groups at their rims. A systematic investigation on how the degree of substitution on the cyclodextrin rims affects the binding affinity for a given guest molecule has however rarely been reported, especially from the perspective of photophysical studies. Herein, we report the non-covalent interaction of a styryl based dye, LDS-798, with three different sulfobutylether beta cyclodextrin (SBE

A cyclodextrin-based fluorescence light-up and ratiometric sensor is reported for highly selective and sensitive recognition of glutathione over cystein and homocystein. The sensing scheme developed builds up on a supramolecular assembly formed between a molecular rotor dye (ThT) and a polyanionic supramolecular host (sulfated-β-cyclodextrin, SCD). The detection scheme is accomplished as follows: firstly, the bivalent Cu2+ quenches the emission from ThT-SCD assembly by causing the dissociation of ThT molecules from SCD surface. Secondly, when GSH is added to the copper-quenched system, owing to specific interaction between Cu2+ and GSH, Cu2+ is removed from the SCD which again allows the formation of ThT-SCD assembly. Indeed, this scheme of disassembly and reassembly successively caused by Cu2+ and GSH in the aqueous solution empowers our sensor framework to work as a good ratiometric sensor for the detection of GSH. The sensor scheme shows a linear response in the range 0–250 μM with a LOD of 2.4 ± 0.2 μM in aqueous solution and 13.6 ± 0.5 μM in diluted human serum sample. The sensor system is excited at 410 nm and the emission signal is plotted as a ratio of intensity at 545 nm (aggregate band) and 490 nm (monomer band). This ratiometric sensor system is highly selective to glutathione over cystein, homocystein, and other amino acids. Additionally, response of the sensor system towards GSH in complex biological media of serum samples demonstrates its potential for practical utility.

Inorganic pyrophosphate (PPi) is a crucial anionic analyte that is involved in various biochemical processes of living systems. The deficiency or excess of the anion leads to several abnormalities in humans. Therefore, PPi has drawn significant attention in the last few years from diagnostic point of view. In this regard, a large number of interesting and exciting research reports have emerged that especially involves nanomaterials. However, there is no review article that acknowledges and critically analyses these nanomaterials-based PPi sensing methods. Herein, we have attempted a detailed analysis of nanomaterial based PPi sensors/biosensors developed in the last 10 years. The sensing principles have been described, in detail, under different nanomaterial sections. Their various analytical performance parameters have been tabulated. The merits and demerits of each class of sensors/biosensors are given. Lastly, a future outline of possible impact of these studies in the development of PPi sensing methods has been highlighted.

A facile synthesis of 1,3,5,7-tetraaryl (thienyl and pyrenyl) substituted BODIPy derivatives from tetramethyl BODIPy and aryl aldehydes via one-pot Knoevenagel reaction conditions has been carried out to yield extensively conjugated BODIPy (1,2). Drastic bathochromic shift of more than 200 nm was observed in absorption (∼up to 700 nm) and emission (up to ∼740 nm) maxima of 1,2 as compared to classical BODIPy (∼500 nm). Nano-aggregates of 1,2 were prepared by re-precipitation method in aqueous medium and are characterized by absorption, emission, transient lifetime, DLS and SEM measurements. These studies revealed the aggregation formation through BODIPy core which is further strengthen by peripheral aryl substituents. Furthermore singlet oxygen production ability of 1,2 and their nano-aggregates were studied. Importantly, the nano-aggregates reveal superior singlet oxygen production ability in the aqueous phase as compared to their monomers in the biologically advantageous near-IR region.

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples.

Objectives: Diagnostics is the first step for the treatment and eradication of infectious microbial diseases. Due to ever evolving pathogens and emerging new diseases, there is an urgent need to identify suitable diagnostic techniques for better management of each disease. The success rate of specific diagnostic technique in any population depends on various factors including type of the microbial pathogen, availability of resources, technical expertise, disease severity and degree of epidemic of disease in the area. One of the important tasks of the policy makers is to identify and implement suitable diagnostic techniques for specific regions based on their specific requirements. In this review we have discussed various techniques available in the literature and their suitability for the target population based on above mentioned criteria. Methods: Diagnostic techniques evaluation of well documented representative microbial diseases; Tuberculosis (bacterial), Malaria (parasitic) and HIV (viral) were included in the study. Identification and collection of information and data was performed focusing on the diagnostic techniques used from the scientific publications from Pubmed, Science Access, Scopus, EMBASE and several regional databases. WHO and CDC database for Tuberculosis, Malaria and HIV were also included. These techniques were compared with respect to the financial resource availability, expertise and management, functional capacity, pathogen virulence and degree of epidemic in the population. Results and Conclusion: In case of Tuberculosis, ELISA and colorimetric techniques are successful in rural and urban communities with 80% – 90% sensitivity. Genotyping and SNP analysis are useful in drug resistant strains. Parasitic disease Malaria also follows the same trend with diagnostic techniques like RDTs being common in both population with fast results and around 90% sensitivity. STD disease like HIV however shows slight different trends due to urgent need of interference in rural epidemics of the disease. Rapid and sensitive immunotechniques like dipsticks and agglutination with almost 100% sensitivity are used in both rural and urban areas. For the confirmation further tests are done like protein Western and NAAT. Advance techniques could be the option for higher epidemic area, drug resistance and disease research, while rapid techniques would be suitable for low income areas and POC facilities. Therefore, suitability of the diagnostic techniques for better management depends not only on the financial resources and assessment skills of a community but sometimes on the disease itself. We have further discussed the technological improvements for specific settings (rural/urban) based on the past research for better management of diseases, which could be implemented for the understanding of understudied and newly emerging diseases.

Discriminating proteins using simple methods is a highly ambitious task. Herein, we provide the first report of a cyclodextrin based supramolecular host-guest assembly, which without involving any specially designed receptor and transducer, yields a distinct fluorescence response i.e., turn-on response towards non-metalloproteins and turn-off response towards metalloproteins, and leads to their detection and discrimination.

Alkaline phophatase (ALP) is indispensable for physiological functioning of living systems, and participates in the hydrolysis of monoester phosphate linkage from biological molecules, such as, nucleic acids, proteins etc. The abnormal concentration of ALP in human blood serum is an indicator of many diseases, therefore, ALP acts as a very useful biomarker for diagnosis of several diseases. In this contribution, we have exploited the unique phenomenon of aggregation induced emission (AIE) to design a rapid, easy, sensitive and highly selective fluorescence “Turn-On” probing system for monitoring ALP activity. The sensing units of the probing system are made up of an AIE active dye, di-anionic 1,2-Bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene salt (BSPOTPE) and polycationic protamine sulphate (PrS) that electrostatically interact with each other to make a highly fluorescent BSPOTPE-PrS supra-molecular complex. Subsequently, the fluorescence of BSPOTPE-PrS complex is efficiently quenched by the introduction of sodium hexametaphospahte, (NaPO3)6. A rapid recovery in the fluorescence (turn-on) is obtained by adding ALP in the basic buffer conditions. The method registers LOD of 28.7 (±3) μU/mL of ALP in the linear concentration range of 0–36 mU/mL. The sensor exhibits remarkable specificity for ALP. The potential application of the sensing probe in real samples is demonstrated successfully in human serum samples.

How to cite this article Kumar A, Kumar A, Kumar A, Sinha C, Kumar N, Singh PK. Acute Exacerbation of Cough as a Precipitating Cause of Hypoxia in COVID-19 Patients. Indian J Crit Care Med 2021;25(11):1324–1325.

In this study, we have developed an aggregation induced emission (AIE) based simple, sensitive, rapid and convenient biosensor for detection of trypsin and organophosphorous pesticides. The biosensor is composed of tetra-anionic sulphonyl derivative of tetraphenylethylene (Su-TPE) and cationic polyelectrolyte protamine (PrS), assembled by electrostatic interactions without any complex process of integration. The AIE property of Su-TPE/PrS system has been studied, in detail, using different spectroscopic techniques, such as, ground-state absorption spectroscopy, steady-state and time-resolved emission spectroscopy. The AIE phenomenon of Su-TPE molecules induced due to Su-TPE/PrS supramolecular complex formation has been supported by studying Su-TPE/PrS system under various environmental factors. After establishing the AIE phenomenon of Su-TPE/PrS complex, the potential of the sensing platform, for trypsin detection, has been explored based on the principle of trypsin dependent PrS hydrolysis. The detection system is highly sensitive in the linear trypsin concentration range of 0–16 nM with detection limit of 0.22 nM. Furthermore, the sensing platform also shows excellent selectivity towards trypsin. More importantly, based on trypsin inhibition, Su-TPE/PrS platform is also responsive towards organophosphorous pesticide detection. The commendable performance of the Su-TPE/PrS biosensor will enhance future development of rapid detection of trypsin along with fast high throughput screening of organophosphrous pesticides.

Designing extrinsic fluorescence sensors for amyloid fibrils is a very active and important area of research. Recently, an ultrafast molecule rotor dye, Auramine O (AuO), has been projected as a fluorescent amyloid marker. It has been claimed that AuO scores better than the most extensively utilized gold-standard amyloid probe, Thioflavin-T (ThT). This advantage arises from the fact that AuO, in addition to its usual emission band (∼500 nm), also displays a large red-shifted emission band (∼560 nm), exclusively in the presence of human insulin fibril medium and not in the native protein or buffer media. On the contrary, for ThT, the emission maximum (∼490 nm) largely remains unchanged while going from protein to fibril. This otherwise unknown large red-shifted emission band of AuO, observed in the presence of human insulin fibrils, was tentatively attributed to a species formed upon fast proton dissociation from excited AuO. It was proposed that because of the long excited-state lifetime (∼1.8 ns) of AuO upon association with human insulin fibrils, this fast proton dissociation from excited AuO could be observed, which is otherwise not observed in buffer or native protein media, owing to its very short excited-state lifetime (∼1 ps). Herein, we show that despite the long excited-state lifetime of AuO in other fibrillar media (human serum albumin and lysozyme), the new red-shifted emission band at 560 nm is not observed, thus possibly suggesting a different origin of the red-shifted emission band of AuO in human insulin fibril medium. We convincingly show that this red-shifted band of AuO (∼560 nm) could be observed under conditions that promote dye aggregation, such as a premicellar concentration of surfactants and polyelectrolytes. These AuO aggregates display strong emission wavelength dependence of transient decay traces, similar to that for AuO in human insulin fibril medium. Detailed time-resolved emission spectral (TRES) measurements suggest that the AuO/premicellar surfactant and AuO/human insulin fibril system share similar features, such as a dynamic red-shift in TRES and an isoemissive point in the time-resolved area-normalized emission spectra, suggesting that the characteristic red-shifted emission band of AuO in human insulin fibril medium may arise from AuO aggregates.

In general, aggregation-prone organic molecules are prevented from self-aggregation in the presence of macrocyclic hosts like β-cyclodextrin because of their preference for the formation of inclusion complex with guest molecules. On the contrary, sulfate-laced β-cyclodextrin has been recently reported to induce the aggregation of some of the non-aggregation-prone organic dyes, which have been subsequently utilized for biosensing applications. In the present contribution, we report the interaction of a cationic organic probe molecule, 1-pyrene methyl amine (PMA), which belongs to one of the most useful families of organic fluorescent probes, that is, pyrene, with a sulfated β-cyclodextrin derivative (SCD). Interaction of a cationic probe with a β-cyclodextrin derivative was studied using a variety of photophysical methods such as ground-state absorption, steady-state emission, and time-resolved emission techniques. Detailed photophysical investigations have revealed that SCD induces the ground-state association of PMA molecules. This SCD-induced aggregation of PMA molecules has been attributed to the charge neutralization of the cationic probe by negatively charged sulfate groups, which subsequently lead to their association because of the close proximity on the rims of cyclodextrin. This monomer-dimer equilibrium of the PMA-SCD system is found to be extremely responsive to external chemical stimuli like temperature, pH, ionic strength of the medium, and organic solvent (dimethyl sulfoxide), which projects them as potential platforms for various sensing applications including bioanalytes. The supramolecular assembly has been demonstrated to sense arginine.

Supramolecular host–guest pairs, with a very high association constant, represent excellent molecular recognition motifs, and serve as useful building blocks for numerous exciting supramolecular functional materials. Cyclodextrins, an important class of glucopyranose-based hosts, generally, suffer from low affinity for most guest molecules (102–104 M−1). Herein, we report a styryl-based fluorogenic probe which registers a very high association constant of 7.84 × 105 M−1 with sulfobutylether substituted β-cyclodextrin in contrast to a low association constant of 1.89 × 102 M−1 with unmodified β-cyclodextrin (β-CD). This exceptionally high binding affinity of the fluorogenic probe with the sulfobutylether substituted β-CD has been attributed to the strong electrostatic interactions between the cationic guest and the polyanionic host along with improved hydrophobic interactions due to the extended butylether groups present on the rims of the cyclodextrin cavity. The significant modulations in the photophysical properties of guest molecule, upon interaction with host molecule, have been investigated, in detail, using ground-state absorption, steady-state fluorescence and time-resolved emission measurements. The effect of temperature and ionic strength of the medium have been employed to investigate the nature of the underlying interactions in the present host–guest system. The possibility of indicator displacement assay involving the present host–guest system has also been demonstrated using a competitive binder.

A fluorescence turn-on probe for amyloid detection in the extreme near-infrared region (>750 nm) is a highly desirable technological evolution from the view point of potential in vivo applications. Herein, we report a molecular rotor-based amyloid sensor probe which, on binding to the insulin amyloid fibril, registers a large turn-on emission in the near-infrared region, and records an exceptionally large red-shifted emission wavelength of ∼770 nm along with a Stokes’ shift of ∼150 nm, the highest reported to date for any amyloid sensor probe, in the insulin fibril bound form, in the near-infrared region. Importantly, when bound to insulin fibrils, this probe also exhibits an exceptionally large red-shift of ∼120 nm in the absorption spectra, which enables the naked eye in vitro detection of amyloid fibrils.

This paper argues that the pursuit of knowledge in the departments of humanities is faced with unprecedented crisis. The crisis emanates from the emergence of a new world order wherein the very idea of a human is questioned. Late capitalism promotes the creation of wealth for its own sake, the advancements in technology and science sketch narrow definitions of knowledge within the confines of objectivity and verifiability, and the whole idea of democracy is reduced to the manipulations of narratives. The study of English literature in India too is faced with this crisis. In this paper, an attempt is made to redefine and reformulate the role of humanities to face the challenges of the emerging world order.

The designing or identification of extrinsic fluorescence probes for the sensitive and selective detection of amyloid fibrils, which can emit in the red to near infrared region, is an extremely important area of research. Long wavelength emission offers various crucial advantages such as preventing auto-fluorescence and photo-damage of specimen, reduced scattering, large penetration depth, etc. Herein, we have identified a hemicyanine based organic dye molecule, LDS722, which displays an impressive fluorescence turn-on emission (~200 fold increase), in the near infrared region of the spectrum, in presence of insulin fibrils. LDS722 also displays a very high selectivity to bind to the fibrillar form of insulin as opposed to its native conformation. Remarkably, the probe also registers a very large Stokes' shift of ~170 nm and a huge red shift of ~120 nm in the excitation spectra. The significant shift in the absorbance maximum of the fibril-bound probe, from its initial free form, results in the visual colour change facilitating naked eye detection of the fibril positive solution. LDS722 could also efficiently monitor the kinetic progression of the fibrillation process without any interference. Importantly, LDS722 also shows a good performance in the human serum matrix with a LOD of 55 nM.

Single-wavelength based fluorescence sensing scheme of ATP have been amply reported in literature whereas, only limited reports exist, where a ratiometric detection scheme for ATP is developed that attain high discrimination against a closely related competitive analyte pyrophosphate (PPi), and constructed from all commercially available molecules. In this work, we report a dye-polyelectrolyte supramolecular assembly which works as an efficient sensor platform for selective and sensitive detection of ATP, and provides a ratiometric output for ATP with LOD of 0.1 μM. The dye-polyelectrolyte supramolecular assembly consists of the monomer-aggregate equilibrium of a tetranionic dye, 1,3,6,8-pyrenetetrasulfonic acid (PTS) on the surface of a positively charged polyelectrolyte, poly(allylaminehydrochloride), PAH. This monomer-aggregate equilibrium is significantly modulated by ATP yielding an advantageous fluorescence ratiometric response. Importantly, the present dye-polyelectrolyte assembly shows very high selectivity for ATP over pyrophosphate which is seldom reported in the literature. More importantly, the sensor platform also displays good response in human serum matrix, indicating its applicability in real-life scenarios. The sensor scheme involves all commercially available components which provide freedom from heavy dependence on synthetic molecules that involves laborious and time-consuming synthetic steps which are expected to significantly impact the prospect of this new sensor scheme in real-life applications.

Water molecules in reverse micelle serve as an excellent model for biological water. However, it has been argued previously that water molecules at the centre, even for smaller sized water pools of reverse micelles, behave like bulk water, using ultrafast vibrational lifetime measurements of azide ion. In the present investigation, the vibrational dynamics of an ultrasmall IR probe, azide ion, has been studied in AOT reverse micelle, at various w0 (radius of water pool), using linear IR measurements, vibrational lifetime measurements and 2D-IR measurements. While linear IR measurements show gradual variation in spectral parameters, such as, peak position and width of the vibrational transition, suggesting a gradual change in the micro environment of the probe with variation in radius of the water pool, the vibrational lifetime remains indistinguishable with variation in w0, which has been ascribed earlier to the location of azide ion in the centre of the water pool. Herein, ultrafast 2DIR spectroscopy convincingly demonstrates that, for a smaller sized water pool, the water molecules, even at the centre of the water pool, behave significantly different as compared to bulk water, an inference, which is missed by the previous vibrational lifetime measurements, and suggest an extensive slowdown of the hydrogen bond relaxation dynamics as compared to bulk water.

Considering the clinical importance of Heparin in anticoagulant therapy, intensive efforts have been devoted to develop optical sensor systems for the specific and sensitive detection of Heparin. However, majority of the reported probes either work through turn-off mechanism or are commercially inaccessible. Herein, we report a molecular rotor based dicationic cyanine derivative, commercially known as YOPRO-1, for effective, economic, simple and quick “turn-on” detection of Heparin. For the first time, the formation of emissive H-aggregates of YOPRO-1 has been demonstrated in any chemical or biological environment that offers an excellent sensing platform for the detection of this important biomolecule, Heparin. In addition, YOPRO-1 also undergoes exceptional changes in its absorption features that presents an opportunity of dual read-out i.e., both, colorimetrically as well as fluorometrically. Apart from sensitive detection (LOD =0.5 nM), YOPRO-1 also shows high selectivity for Heparin as compared to its structurally related analogs. Importantly, the commercial availability of this probe molecule presents an advantage over synthetically challenging probe molecules. More importantly, the dicationic YOPRO-1 shows improved response in high percentage of serum matrix over previously reported monocationic probes and represents a significant advance in the field of Heparin sensing.

The development of fluorescence based sensor for perrhenate anion, which serves as a non-radioactive surrogate of hazardous pertechnetate anion, is an extremely rewarding task but nevertheless has remained rarely investigated in literature. Further, there are no reports in literature that propose a lifetime based sensing of perrhenate anion which provides significant advantage over pure intensity based sensor. Herein, we report an extremely simple fluorescence sensor for perrhenate anion in aqueous media, where we have used 1-pyrenemethylamine (PMA) as fluorescent probe. The fluorescence intensity of PMA is heavily quenched along with drastic reduction in the excited-state lifetime of PMA that provides an excellent opportunity for a very sensitive detection of perrhenate anion (LOD = 14 μM). Importantly, PMA also displays high selectivity towards perrhenate anion when compared with several other environmentally ubiquitous anions. The selective interaction between PMA and perrhenate has been attributed to the high basicity of ReO4− anion which facilitates a strong H-bonding interaction with amino group of the probe and the quenching interaction is attributed to the photoinduced electron transfer between excited PMA and ReO4−. Overall, an extremely simple, selective and sensitive fluorescence sensor for perrhenate anion is reported which also operates through lifetime measurement that is first of its kind.

Background: Studies have reported that dental procedures may serve as a portal of entry for bacteria into the blood circulation, commonly termed as bacteremia which may inhabitate the heart and joints subjected to repair and replacement by prosthesis and may lead to complications in immunocompromised patients. Dental procedure may play a pivotal role in the development of infective endocarditis and infection around the prosthetic joint. Antibiotic use is suggested for all dental procedures requiring gingival manipulation or of the periapical region of teeth or mucosal incision in these patients. Objective: The present study has been conducted to inspect the antibiotic prescribing practices of general dentists among 250 dental practitioners. Methods: The study was conducted on 250 dental surgeons practicing in the urban Indian population of various parts of the country. A validated questionnaire was developed by a multidisciplinary dental and medical team and was circulated on the subject of the basic knowledge and awareness about antibiotic prophylaxis in susceptible patients. The data from the participants were collected, collated, and statistically analyzed. Results: The present study comprised 250 dental surgeons; 178 out of 250 were male, whereas 72 were female. Antibiotic prophylaxis guidelines were followed by 169 practitioners (67.60%), whereas 81 (32.40%) dentists did not follow any guidelines. Out of 169, 67 followed the American Academy of Orthopaedic Surgeons (AAOS) guidelines (39.64%), 58 followed American Heart Association (AHA) guidelines (34.30%), whereas 44 followed general physician's guidelines (26.03%). On screening the underlying conditions for which antibiotic cover was prescribed, it was shown that majority of the dental surgeons did the same for patients with cardiac valve repair or replacement (230; 92%), followed by infective endocarditis (212; 84.80%); organ transplant (212; 84.405); diabetes (189; 75.60%); prosthetic joint replacement (150; 60%); and congenital heart defect (110; 44%). Conclusion: Patients should then be trained to perform meticulous oral hygiene and advised to schedule regular dental checkups to maintain optimal dental health. Dentists should use antibiotic prophylaxis in only conditions associated with a valid scientific basis and should follow the standard protocols recommended by the American Dental Association, AHA, or AAOS.

Common milk allergens, such as, β-lactoglobulin (β-LG), poses a major health concern for public, particularly in children. Thus, sensitive and selective methods for detection of common milk allergens are highly warranted. To the best of our knowledge, detection and quantification of β-lactoglobulin, a common milk allergen, by fluorescence based technique has not been reported till date. Herein, we present the first ever fluorescence based report for the selective detection and quantification of milk allergen, β-LG, using LDS-798 as a fluorogenic probe, which registers an exceptionally large fluorescence enhancement of ∼2900 fold in the far-red region upon binding with β-LG with LOD of ∼6.3 (±0.3) nM for β-LG in aqueous buffer solution and 0.67 (±0.04) μM in 5% bovine milk matrix respectively. High sensitivity and selectivity, fast response, high repeatability and reproducibility, easy operation, along with emission in the technologically advantageous far-red region make the fluorometric quantification of β-LG, using LDS-798 as a fluorogenic probe, far more advantageous than the other techniques, generally used for β-LG quantification. Importantly, we have demonstrated the applicability of this probe for quantification of β-LG in real milk samples which has been validated by an established method.

Stimuli-responsive supramolecular host assisted guest aggregation has attracted tremendous attention, of late, because of its various technological applications. However, a large majority of them involve anionic supramolecular hosts such as p-sulfonato calixarenes, sulfated cyclodextrin and so on, in combination with cationic guests. On the other hand, the phenomenon of host-assisted aggregation of anionic guests with cationic supramolecular hosts, which can significantly broaden the scope of this exciting field, has rarely been reported in the literature. In the present work, we report, host assisted aggregation of an anionic organic probe molecule, pyrene tetrasulfonate (PTS), in the presence of a cationic cyclodextrin derivative, amino-β-CD (AβCD), which has been studied, in detail, using various spectroscopic techniques including UV–Vis spectroscopy, fluorescence spectroscopy, time-resolved spectroscopy, and molecular docking calculations. The effect of ionic strength of the medium on the photophysical properties of PTS-AβCD complex indicates that electrostatic interaction is the predominant force in assisting the formation of PTS-AβCD complex. The monomer-aggregate equilibrium of PTS in the present system is also found to be extremely sensitive towards external stimuli like temperature, and pH of the medium. Finally, the PTS-AβCD assembly has been used for sensing an important charged bio-analyte, adenosine triphosphate (ATP), demonstrating the applicability of the present host-guest system.

Perrhenate oxoanion is a non-radioactive surrogate of the radioactive and hazardous pertechnetate oxoanion. The efficient sensor systems for perrhenate anion in aqueous medium is barely reported and still remains challenging due to low charge density and large size of the anion. In this regard, we have identified a cyanine based molecular rotor probe, pseudoisocyanine, which produces an appreciably larger emission enhancement of ∼60 fold in response to perrhenate anion, which is highest reported, till date, for any turn-on sensor for perrhenate anion leading to a significant improvement in the detection limit (0.17 μM) over existing sensors for perrhenate. Our sensing scheme operates through the ion pairing interaction between perrhenate and pseudoisocyanine which induces the formation of J-aggregates of pseudoisocyanine that yield dramatic changes in its fluorescence properties. The J-aggregate formation of pseudoisocyanine, in the presence of perrhenate anion, also yields significant changes in the absorption properties providing an opportunity of dual sensing of perrhenate, i.e. via fluorimetry and colorimetry. Apart from being sensitive and selective, our probe molecule exhibits a desirable feature of emission and excitation wavelength lying in the red region of the visible specrum which is advantageous for operation of a probe molecule in complex sensing matrix.

Triblock copolymer and surfactant based supramolecular assemblies have been used for the controlled sequestration of the DNA intercalator. The triblock copolymer micelles do not affect the molecules that are intercalated in the DNA. However, on addition of charged surfactant to the triblock copolymer micellar solution, sequestration of the intercalated molecules from DNA to the polymer-surfactant supramolecular assemblies takes place. Such sequestration of the intercalated molecules in the polymer-surfactant supramolecular assemblies has been explained on the basis of the charged surface formed in the polymer micelles due to the addition of surfactants. Sequestration of the intercalated molecules from the DNA to the polymer-surfactant supramolecular assemblies has been monitored through the ground state absorption, steady state, and time-resolved emission measurements. It is shown that the extent of sequestration of the intercalated molecules can be finely tuned by tuning the concentration of the surfactant in the triblock copolymer solution. Quantitative sequestration of the intercalated molecules by the supramolecular assemblies has been achieved. Such controlled sequestration of the DNA intercalated molecules by polymer-surfactant supramolecular assemblies can be used to study the binding of drug with DNA and may be useful in applications like detoxification in the case of drug overdose.

Most macrocyclic host molecules, including cyclodextrins, usually prevent self-aggregation of the guest organic molecules, by exploiting inclusion complexation of the guest with the host. In this work, it was found that a negatively charged β-cylcodextrin derivative induces aggregation of a well-known amyloid sensing dye, Thioflavin-T, and leads to an unprecedented formation of the rarely observed emissive H-type aggregates of the dye.

The emission properties of Thioflavin-T (ThT), a cationic molecular rotor, have been investigated in two fluoroalkylphosphate ([FAP]) anion based ionic liquids, namely, 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate and 1-(2-hydroxyethyl)-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, over a wide temperature range. The micro-viscosities of ionic liquids around ThT, measured from the emission quantum yield, are found to be quite different from their bulk viscosities. The temperature dependence of the viscosity and the emission quantum yield reveals that, despite the very low shear viscosity of these ILs, the non-radiative torsional relaxation has a strong dependence on the free volume of these [FAP] anion based ILs.

Objective: The phenomenal popularity of social networking sites has been used globally by medical professionals to boost professional associations and scientific developments. They have tremendous potential to forge professional liaisons, generate employment,upgrading skills and publicizing scientific achievements. We highlight the role of social networking mediums in influencing teaching, training and research in anaesthesiology. Background: The growth of social networking sites have been prompted by the limitations of previous facilities in terms of ease of data and interface sharing and the amalgamation of audio visual aids on common platforms in the newer facilities. Review: Contemporary social networking sites like Facebook, Twitter, Tumblr,Linkedn etc and their respective features based on anaesthesiology training or practice have been discussed. A host of advantages which these sites confer are also discussed. Likewise the potential pitfalls and drawbacks of these facilities have also been addressed. Conclusion: Social networking sites have immense potential for development of training and research in Anaesthesiology. However responsible and cautious utilization is advocated.

Large posterior mediastinal masses may lead threatening complications such as critical tracheobronchial compression. Airway management in these individuals is a challenge and being a lower airway obstruction; rescue strategies are limited. We encountered one such case of a large esophageal mucocele causing extrinsic tracheobronchial compression. We have described the anesthetic management of this case using awake fiber-optic assessment followed by intubation. Close communication with the surgical team, meticulous planning of airway management, and early drainage of the mucocele are the cornerstones of management in such patients.

Heparinase is a mammalian endoglycosidase which specifically degrades Heparin, the widely used blood-anticoagulant, into smaller fragments and produces therapeutically important low molecular weight Heparin. More importantly, the increased expression of Heparinase was found to correlate with malignancy of tumour and its ability to metastasize. Considering the various crucial biological roles played by Heparinase, it is important to develop detection scheme for Heparinase. However, very few reports exist for detection of Heparinase, especially from the viewpoint of ratiometric detection. Herein, we report a selective and sensitive fluorescence ratiometric sensor for the detection of Heparinase that has been developed by utilizing a fluorescent complex of a molecular rotor dye, Thioflavin T with Heparin. Heparinase specifically degrades Heparin into smaller fragments which leads to the release of the Thioflavin-T aggregates from the surface of Heparin and leads to large modulations in the fluorescence properties of Thioflavin T-Heparin complex. The sensing mechanism has been demonstrated by utilizing a variety of spectroscopic techniques such as ground-state absorption, steady-state and time-resolved emission and circular-dichroism spectroscopy. The sensing scheme provides a simple, sensitive, selective, and label-free approach for detection of Heparinase. Importantly, the sensing scheme involves all commercially available molecules which provides a significant advantage in terms of relief from extreme dependence on time-consuming and tedious synthetic pathways. More importantly, the current sensing scheme also shows response towards Heparinase in serum matrix.

Protamine, an arginine rich polycationic peptide, is the only clinically approved antidote of Heparin and has been successfully used in reversing the action of Heparin in case of Heparin overdose, a situation which can have fatal outcomes. Therefore, developing sensors for Protamine is of uttermost importance in clinical diagnosis. However, only limited reports are available on optical detection of Protamine, since it is relatively difficult to detect Protamine due to its composition, which is devoid of aromatic amino acids. In the present contribution, we describe a fluorescence turn-on sensing scheme for Protamine which utilizes the phenomenon of aggregation induced emission of an anionic derivative of tetraphenylethene, i.e. sodium 1,2-bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene (BSPOTPE) on interaction with Protamine. The interaction between BSPOTPE and Protamine has been thoroughly investigated using various photophysical techniques, which include, ground state absorption, steady-state and time-resolved emission spectroscopy, and molecular docking calculations. The interaction of BSPOTPE with Protamine leads to large modulation in its photophysical properties, with an enhancement of ~70-fold in emission intensity and significant modulation in excited-state lifetime. Apart from being simple and selective, the present sensor system is highly sensitive for Protamine with a LOD of 47 pM in aqueous solution. Importantly, BSPOTPE is a commercially available probe molecule which provides freedom from the tedious and time-consuming protocols to develop synthetic probe molecules for sensor applications, which normally serves as an impediment for real-life applications.

Background: N-acetyl cysteine, a mucolytic agent, demonstrates free radical scavenging and anti-inflammatory properties, and prevents endothelial dysfunction by inhibition of NF-KB and formation of no adducts. This has a potential role to tackle cytokine storms, endothelial dysfunction and prothrombotic state observed in COVID-19 manifestations like ARDS and Multi organ dysfunction.Methods: Institution based descriptive cross sectional study, 164 patients from laboratory confirmed RT PCR positive COVID-19 patients, in the study period from 27th May 2020 to 10th August 2020, were assessed, in medical college Kolkata, a dedicated COVID-19 care facility.Results: It was observed that moderate-severe patients who received N-acetyl cysteine along with standard therapy had average hospital stay duration of 12 days, higher rate of discharge, average duration of oxygen therapy of 8 days, less number of deaths and reduced transfer to critical care facilities.Conclusions: N-acetyl cysteine can be considered as an adjunctive therapy with standard protocol driven care, due to its beneficial anti-inflammatory and free radical scavenging properties.

The 1′-hydroxy-2′-acetonaphthone (HAN) is a well-known excited-state intramolecular proton-transfer (ESIPT) dye that has been used as a useful fluorescence probe to understand various homogenous and microheterogenous media. However, interaction of HAN with proteins is still largely less explored. The present study is aimed to investigate the interaction of HAN with the most abundant animal circulatory protein, bovine serum albumin (BSA), using multi-spectroscopic techniques and molecular docking studies. The photophysical properties of HAN undergo significant modulation upon its interaction with BSA protein. The confinement and reduced polarity experienced by bound HAN into BSA binding pocket causes a large fluorescence enhancement. The binding constant for HAN-BSA complex is evaluated to be ∼4.3 × 104 M−1. Time-resolved fluorescence measurements reveal the exclusive presence of only keto (K*) form and twisted keto rotamer (KR*) form of the dye in the excited state inside the BSA binding pocket, though in the ground state the dye exists entirely in its enol (E) form. Results suggest a quantitative ESIPT reaction for HAN even inside the BSA pocket. Time resolved fluorescence anisotropy studies indicate very tight binding of HAN into the BSA pocket such that independent rotational diffusion of the dye is completely ceased. Molecular docking studies provide best docking conformation and involved interaction forces, suggesting the preferred binding of HAN to the site IIA (Sudlow's site I) of the BSA protein. Observed photophysical results provide valuable insights of HAN–BSA binding interaction, revealing for the first time that the intriguing excited-state equilibrium between K* and KR* forms of HAN is largely shifted towards KR* form, as the dye binds to the BSA pocket. To the best of our knowledge such an intriguing modulation in the excited state prototautomeric conversion process has not been reported before for the studied dye in the presence of any other host. Results of the present study can be useful in understanding the pharmacology of structurally similar dyes/drugs, having relevance to drug delivery, pharmaceutical sciences, sensors, and so on.

The self-aggregation of the aggregation prone molecules are avoided by employing a macrocyclic host molecule, such as β-cyclodextrin, which commonly favours the inclusion complex formation with the guest molecule and prevents the self-aggregation of the guest molecule. On the contrary, the substituted host molecules, with multiple charges are reported to promote self-aggregation of guest molecules, specifically when the guest molecules are oppositely charged. One such interesting anionic host molecule is sulfobutylether substituted β-cyclodextrin (SBE7-β-CD), which possesses both extended hydrophobic cavity as well as relatively high negative charge which makes this host capable of forming both stable inclusion complexes with the incoming guest molecule as well as inducing aggregation of guest molecules. However, there are only limited reports of this host inducing aggregation of guest molecules. In the present work, we report the interaction of SBE7-β-CD with a versatile cationic fluorescent probe, 1-pyrenemethyl amine (PMA), using ground-state absorption, steady-state emission, and time-resolved emission measurements. Interestingly, in contrast to various reports, SBE7-β-CD is found to promote the aggregation of PMA molecules. These aggregates are confirmed by the changes in the emission spectra of PMA by emergence of a distinct broad emission band at around 493 nm, which is largely red-shifted from the monomer emission peaks of PMA which appear at 375 and 395 nm. The detailed investigation of the photophysical properties of this assembly discloses that association of PMA molecules in their ground-state is induced by SBE7-β-CD instead of forming excimers in the excited state. These aggregates are found to show significant and reversible response to external stimuli such as ionic strength of medium and temperature, which makes this system to be responsive aggregate assembly to be explored in sensing applications of biochemically important analytes, which has been demonstrated by sensing Lysine and Arginine, important basic amino acids, using this PMA-SBE7-β-CD assembly.

Protamine is an arginine rich cationic protein and is known to be a very important pharmaceutical compound which is utilized in interventional radiology procedures, vascular surgery, and cardiac surgery, and is the only clinically approved antidote for Heparin overdose. Considering its importance in various biological processes, it is very important to develop sensor platforms for selective and sensitive detection of Protamine. Herein, we present a rarely reported ratiometric fluorescence detection scheme for Protamine, which is based on Protamine-induced disassembly of a dye-polyelectrolyte supramolecular assembly that causes a tuning of the monomer-aggregate equilibrium of the dye, and yields a sensitive ratiometric response for the Protamine. Our sensor system registers high sensitivity and selectivity for Protamine. Besides being simple, selective and sensitive, one of the prime features of this developed detection method is its ratiometric response which principally provides increased accuracy for quantitative analysis in complex samples due to inherent internal calibration of two bands. Another noteworthy feature associated with this detection scheme is that it employs commercially available probe molecule and other components that avoid the heavy dependence on time-consuming and tedious synthetic procedures involved with the previously existing methods. Importantly, our current sensing scheme also demonstrates sensing performance in complex human serum matrix.

In comparison to traditional calyx[4]arene, thiacalix[4]arene is unique due to its bridging S-atoms. Therefore, functionalized p-sulfonato thiacalix[4]arene has been used for the detection of some transition metal ions. The inclusion behavior between the important water soluble p-sulfonato thiacalix[4]arene with fluorescein and M2+ (Co2+, Ni2+, Cu2+, Zn2+) ions has been studied using a spectrofluorometric method. 1H NMR, 2D NMR and IR spectra also supported the complexation. The complex stability follows the order Cu2+ > Zn2+ > Co2+ > Ni2+, which is supported by the Irving-Williams series. The combined results demonstrate the cooperative interaction of the M2+ ions with p-sulfonato thiacalix[4]arene and this is further supported by a molecular docking study.

The crucial involvement of amino acids in various physiological processes and their ability to function as effective biomarkers for a variety of diseased conditions has inspired a significant activity in conceptualizing sensor system for amino acids, although there are still limited reports which aim to detect basic amino acids with simpler design yet with high sensitivity and selectivity. Herein, we report a ratiometric optical sensor that is based on Arginine and Lysine-induced disintegration of a supramolecular assembly, leading to significant modulation in the monomer-aggregate equilibrium, which yields a ratiometric signal that has been used for quantification of Lysine and Arginine in aqueous solutions. Our sensor design overcomes many disadvantages that are associated with the existing optical sensing schemes, such as, technically demanding and time-consuming synthetic protocols for probe synthesis, limited aqueous solubility, and more importantly, most of the previously reported sensors operate via single wavelength based measurements, which makes their performance error prone to a variety of analyte-independent factors which can be overcome by ratiometric detection as achieved here. Overall, we have devised a label free, rapid, simple, dual-sensing, ratiometric sensor for the detection of basic amino acids. Importantly, our sensing system also shows response in the human serum matrix.

Devising sensors for the perrhenate anion in aqueous media is extremely challenging, and has seldom been reported in the literature. Herein, we report a fluorescence turn-on sensor for the perrhenate anion in aqueous media based on the aggregation-induced emission of a popular ultrafast molecular rotor dye, Thioflavin-T. The selective response towards the perrhenate anion has been rationalized in terms of matching water affinity, with the weakly hydrated perrhenate anion spontaneously forming a contact ion pair with the weakly hydrated ultrafast molecule-rotor-based organic cation, Thioflavin-T, which in turn leads to an aggregate assembly that provides a fluorescence turn-on response towards perrhenate. The sensing response of Thioflavin-T has been found to be quite selective towards the perrhenate anion when tested against anions that are ubiquitously present in the environment, such as chloride, nitrate, and sulfate anions. The formation of self-assembled Thioflavin-T aggregates has also been investigated by time-resolved emission and temperature-dependent measurements.

Heparin is the second most widely used natural drug and an extensively employed blood anticoagulant worldwide. Construction of fluorescent sensors for Heparin has remained heavily dependent on the complex and time-consuming laborious synthetic efforts. However, reports on the direct usage of in-expensive commercially available probe molecule, for sensitive and selective fluorimetric sensing of Heparin, which can greatly simplify the synthetic efforts, has been limited and remains highly desirable. Herein, we report a very sensitive and selective fluorescence turn-on sensor for Heparin, which utilizes a commercially available organic dye molecule, Pseudoisocyanine. The supramolecular interaction between the Pseudoisocyanine and Heparin leads to the J-aggregate formation of Pseudoisocyanine on the surface of Heparin, with an exceptional fluorescence enhancement of ∼400 fold. The J-aggregates of Pseudoisocyanine also display remarkable changes in the absorption features, in the presence of Heparin, which provides a unique advantageous feature of dual sensing of Heparin, by colorimetry and fluorimetry. Pseudoisocyanine also displays high selectivity towards Heparin over its structurally related analogs Chondroitin sulphate and Hyaluronic acid, and other analytes, with a detection limit of 2 nM. More importantly, our sensor system shows good performance in the serum samples, a complex biological media. We further demonstrate that, the interaction of Heparin with its only medically approved antidote, Protamine can also be monitored using Pseudoisocyanine J-aggregates. Thus, our assay is sensitive and selective, rapid, simple, and inexpensive, which can promote the Heparin related biochemical and biomedical research.

Developing sensitive and selective near-infrared fluorescent bio-probes for serum albumin detection is an ambitious and highly rewarding task. Herein, we report a styryl based fluorophore for serum albumin detection, which displays an exceptional turn-on emission enhancement of ∼500 fold, the highest reported so far in the near-infrared region, and more importantly enables quantification of albumin in the complex serum matrix.

Objective Identification of risk factors that might be responsible for postoperative hypoxaemia, in view of changing profile of surgical patients and better but more complex perioperative care nowadays. Methods We conducted a prospective observational study that included patients aged 18-65 years, who underwent elective surgery and required general anaesthesia. Oxygen saturation was monitored before the induction in operating room and continued 72 hours post-surgery. Patients were maintained on room air if SpO2 remained >94%. If SpO2 was between 90% and 94%, then patients were provided oxygen therapy via face mask (flow rate at 5-6 litre min-1). If SpO2 was between 89%-85% despite oxygen therapy with face mask, the Bilevel Positive Airway Pressure (BiPAP) was applied. If SpO2 was 90% on BiPAP, then patient was intubated, and ventilatory support was provided. Results Out of 452 patients, 61 developed SpO2 ≤94% requiring oxygen therapy (13.5%). Oxygen therapy by face mask was required in 51 patients, BiPAP in 8 and ventilatory support with endotracheal intubation in 2. Age, body mass index (BMI), smoking status, presence of preoperative respiratory disease, SPO2 (on room air) at baseline and immediately after the transfer to the post-anaesthesia care unit (PACU) were independently associated with postoperative oxygen therapy. Conclusion The risk of postoperative hypoxaemia was highest in patients aged 51-65 years, BMI higher than 30, current and former smokers, pre-existing respiratory disease, chronic obstructive pulmonary disease, patients with 96% oxygen saturation or less at baseline or after shifting to PACU. The type of surgical incision, duration of surgery and dose of opioids administered were not independent risk factors.

Using sub-picosecond fluorescence upconversion spectroscopy, the effect of supramolecular confinement on the ultrafast excited state torsional dynamics of an amyloid fibril sensing dye, Thioflavin-T (ThT), is investigated in a novel cyclodextrin derivative, Sulphobutylether β-cyclodextrin (SBE-β-CD). The encapsulation of ThT inside the nanocavity of SBE-β-CD results in a significant increase in the emission intensity and the excited state lifetime of ThT when compared with native β-CD. Detailed analysis of the time-resolved emission spectra (TRES) shows that the time dependent changes in the integrated area, mean frequency and the width of the emission spectra are appreciably slower as compared with bulk water and native β-CD. These features suggest a significant confinement effect on the ultrafast torsional dynamics of ThT. The ionic strength of the medium significantly affects the complexation of ThT with SBE-β-CD, which indicates that the interaction between the host and the guest is predominantly electrostatic in nature. The results further suggest that the hydrophobic interaction in SBE-β-CD, although minor in contribution in the present case, is comparatively stronger than the native β-CD.

The aggregation of proteins into the amyloid fibrils is mainly responsible for several neurological diseases. Knowledge of dynamics in amyloid fibril is very essential to understand its biological activity. Although, the effects of environment like pH, ionic strength, temperature, etc. on the fibril have been studied extensively, studies on the dynamics of amyloid fibril and the role of water in fibril are scarce. In this article, we have reported the results on the excited state dynamics of amyloid fibrils formed by a well-known blood plasma protein, human serum albumin (HSA), at neutral pH. The sole tryptophan residue, W214, has been used as the intrinsic fluorescent probe to monitor its excited state dynamics. Steady-state and time-resolved fluorescence data suggests that the W214 becomes more closer to the quencher amino acid residues in the fibrillar phase than in the native protein. From detailed time-resolved emission measurements, it is shown that despite having a more ordered structure, the water molecules around W214 in amyloid fibril is more labile than that in the native protein. Fluorescence depolarization studies also indicate that the W214 residue is located in a relatively more flexible region of the ordered amyloid fibril than that in the native protein.

Formation of a ternary complex by an ultrafast molecular rotor (UMR) with a macrocyclic cavitand has been investigated for the sensitive detection of the alkyl chain of a surfactant. A benzothiazole based UMR, Thioflavin-T (ThT), has been used as a fluorescent probe. It is shown that ThT forms a very weak inclusion complex with γ-cyclodextrin (γ-CD) with an association constant of 8.8 M(-1). However, the addition of a small amount of surfactant results in a significant increase in the emission intensity of ThT in γ-CD solution. From detailed steady-state and time-resolved fluorescence measurements and NMR studies, it has been inferred that the addition of the surfactant results in the formation of a ternary complex through the inclusion of its alkyl chain inside the γ-CD nanocavity. In such a ternary complex, the non-radiative torsional motion in ThT is largely prevented due to a large increase in the frictional force inside the nanocavity and results in a significant fluorescence enhancement. The formation of the binary and the ternary complexes in the present system has been further supported by the molecular docking and subsequent molecular dynamics simulation studies. The present result indicates that the inclusion complex with an UMR as a guest could be a potential candidate for the efficient detection of insoluble organic molecules, especially hydrocarbons.

In this communication, using sub-picosecond resolved fluorescence upconversion spectroscopy, we discover that despite a large fluorescence enhancement observed for thioflavin-T in insulin fibrils, the majority of fibril bound thioflavin-T undergoes efficient ultrafast conformational relaxation, and thus does not contribute to the characteristic fluorescence enhancement.

Benzothiazole based ultrafast molecular rotor, Thioflavin T (ThT), is a well known fluorescence sensor for nucleic acids. Thus, the knowledge of mode of interaction between ThT and DNA is very important for efficient utilization of such fluorescence sensors. In the present article, we have reported detail studies on the mode of interaction between ThT and a natural DNA using steady-state and femtosecond time-resolved transient emission techniques. Detail steady-state studies show that ThT binds strongly with natural DNA and causes a large change in its spectroscopic properties. Femtosecond transient emission studies show a substantial decrease in the torsional motion in the excited state of ThT bound to DNA molecules, indicating a strong interaction between them. It is observed that ThT binds to DNA through two modes of interaction. Studies with salt indicate that large fraction of ThT binds to DNA by electrostatic interaction, whereas, viscosity and resonance energy transfer studies indicate the intercalation of ThT with DNA molecules.

Extubation after general anesthetic procedures is often accompanied by transient undesirable responses such as hypertension, tachycardia, coughing, bucking, and raised intracranial and intraocular pressures. In neurosurgical procedures, they need to be stringently controlled to prevent the rise in cerebral blood flow, increase in intracranial pressure, and intracranial bleeding. Intravenous (IV) lignocaine (1-1.5 mg/kg) administration is one such method to blunt extubation responses. We describe a case where IV lignocaine was administered within the recommended doses to inhibit the extubation response, but the same resulted in generalized convulsions because of the clinical and physiological status of the patient at that point of time. Intravenous lignocaine administered to obtund extubation responses can itself manifest in toxic reactions depending on the preexisting clinical and physiological state of the patients. Thus, extreme caution and vigilance is to be maintained whenever IV local anesthetics are used for such purposes.

The existence of neural connection between the limbic system (hypothalamus, hippocampus, amygdala, and other adjacent areas) and the autonomic nervous system has been postulated to trigger severe hemodynamic responses. The hemodynamic consequences of stimulation of amygdala or hippocampus have been sporadically reported in animal studies and adult patients. However, the effect of this stimulation in pediatric patients is scarce. We present our experience of three cases of sympatholysis during intraoperative manipulation of amygdalohippocampus and review the pertinent literature.