Galen’s theory of black bile is strongly influenced by his aim to bring together a wide range of material from the work of different physicians and philosophers that begins with Hippocrates. This has caused there to be a large amount of inconsistencies in his writing on black bile. There has been a tendency in modern scholarship either to try to resolve these inconsistencies or to ignore them completely. In many cases there has been an emphasis on the definition of black bile in the Hippocratic On the Nature of Man as the most important basis for understanding Galen’s characterisation of black bile. My analysis will challenge this assumption concerning the dominance of On the Nature of Man for Galen’s use of black bile in his explanation of health and disease in the body. I shall show that an investigation of the way that Galen characterises the physical properties and function of black bile reveals that it is better to understand his use of this humour in terms of his attempt to bring material from a wide range of authorities together to support the arguments that he presents in his treatises. Galen defines black bile as three distinct types of substance that differ in physical properties in order to account for the different ways that this humour is characterised and defined in the various medical sources that he draws upon. However, he is unable to produce a theory of black bile without inconsistencies relating to a number of issues that include such factors as his naming of the different forms of black bile and his concept of authenticity of texts in the Hippocratic Corpus. Galen’s strategy is to make his audience believe that there is a comprehensive and well-defined theory of black bile that originates in the work of Hippocrates and was followed by certain physicians and philosophers afterwards. But in reality this is just a façade and Galen defines and uses black bile in many different and inconsistent ways for his arguments and refutations that cannot always be reconciled with the content of his sources.

A infecção das vias biliares é uma doença freqüente com alta morbidade e mortalidade, que pode variar de 10 a 60% dependendo de sua gravidade. A causa mais comum desta infecção é a presença de cálculos na via biliar principal que propicia o surgimento de bacteriobilia. O profundo conhecimento das características microbiológicas da bile nos casos de coledocolitíase e infecção das vias biliares são fundamentais para o melhor diagnóstico desta infecção e escolha da antibioticoterapia a ser instituída. Assim, o objetivo deste estudo foi de caracterizar os principais aspectos microbiológicos da bile dos pacientes com e sem coledocolitíase e avaliar sua importância na escolha dos antimicrobianos para o tratamento da infecção das vias biliares. Foram analisados 33 pacientes que foram divididos em um grupo de 10 pacientes sem coledocolitíase (grupo controle) no momento da Colangiografia Endoscópica (CPER) e em outro grupo de 23 pacientes com coledocolitíase. A bile de todos os pacientes foi coletada no início do procedimento endoscópico, através de catater introduzido na via biliar. O exame de microscopia direta com coloração de Gram e as culturas da bile foram negativas nos 10 pacientes que não apresentaram coledocolitíase durante a CPER. Dos 23 pacientes com cálculos na via biliar principal, 19 (83%) apresentaram culturas positivas. Desses 19 pacientes com culturas de bile positivas, 18 (94,7%) apresentaram microorganismos detectáveis à microscopia direta com coloração de Gram. Apenas um paciente apresentou crescimento de germe anaeróbio (Bacteroides fragilis). O cultivo de 28 bactérias teve predominância de microorganismos Gram negativos (18 bactérias- 64,3%). Os germes isolados foram E. coli (9, 32,1%), Klebsiella pneumoniae (5, 17,9%), Enterococcus faecalis (5, 17,9%), Streptococcus alfa-haemoliticus (3, 10,7%), Streptococcus viridans (2, 7,1%), Enterobacter cloacae (2, 7,1%), Panteona aglomerans (1, 3,6%) e Pseudomonas aeruginosa (1, 3,6%). Todos os pacientes com microorganismos detectados pela microscopia direta com coloração de Gram tiveram crescimento bacteriano em suas culturas, por outro lado nenhum paciente com cultura negativa apresentou microoorganismos à microsopia direta ( p= 0,0005). Nesses casos, a microsopia direta apresentou uma especificidade de 100% e sensibilidade de 80%. A análise quantitativa das culturas da bile mostrou que das 19 culturas positivas, 12 (63,2%) tiveram pelo menos um germe com contagem superior a 105 ufc/ml. Todas as bactérias Gram positivas isoladas foram sensíveis à ampicilina, da mesma forma que todas as Gram negativas foram sensíveis aos aminoglicosídeos. Os achados deste estudo demonstram uma boa correlação entre a microscopia direta da bile com coloração de Gram e os achados bacteriológicos das culturas da bile coletada por colangiografia endoscópica retrógrada. O esquema terapêutico antimicrobiano tradicionalmente empregado em nosso hospital, que inclui a combinação de ampicilina e gentamicina, parece ser adequado, pois apresenta eficácia terapêutica contra os principais microorganismos responsáveis pela infecção das vias biliares. / Acute cholangitis is an important cause of emergency admission for acute abdomen. The bacterial infection of the biliary system is associated with obstruction caused by ductal stones. Ductal obstruction leads to a raised intrabiliary pressure with bacteriobilia, cholangiovenous reflux, and bacteremia, which may progress to septicemia. We have studied the bacteriology of bile and clinical manifestations of 23 patients with choledocholithiasis and 10 patients without evidence of choledocholithiasis by endoscopic retrograde cholangiography. Nineteen (82.6%) of 23 patients with choledocholithiasis had positive bile cultures, and none of the patients without choledocholithiasis had positive bile cultures. A single microorganism was detected in 11 (57.9%) patients, while a mixed growth, with pathogens ranging from two to three species, were seen in 8 (42,1%) patients. Patients with clinical manifestations of cholangitis such as fever, abdominal pain, and jaundice (Charcot’s triad) had significant higher counts of colonies per ml of bile (p <0.001). The predominant microorganisms isolated were Escherichia coli (32,1%), Klebsiella spp. (17,9%), Enterococcus faecalis (17,9%), Streptoccus alfa-hemoliticus (10,7%), Enterobacter cloacae (7,1%), Streptococcus viridans (7,1%), Pseudomonas aeruginosa (3,6%), and Bacteroides fragilis (3,6%). In vitro susceptibility testing of the aforementioned biliary pathogens revealed ampcillin and gentamicin to have higher spectrum of antimicrobial activity. In summary, patients with choledocholithiasis have a high recovery rate of bacteria from the bile. The severity of biliary infection is associated with higher concentrations of bacteria in the choledocal bile. The data suggest that antimicrobial therapy of biliary tract infections should combine good in-vitro activity against Enterobacteriaceae (mainly Escherichia coli and Klebsiella spp.) and Enterococcus. spp. Based on the in vitro susceptibility testing of the isolated biliary pathogens, the combination of ampicillin and gentamicin seems to be an appropriate therapeutic regimen for biliary tract inferctions.

Resumo não disponível

A infecção das vias biliares é uma doença freqüente com alta morbidade e mortalidade, que pode variar de 10 a 60% dependendo de sua gravidade. A causa mais comum desta infecção é a presença de cálculos na via biliar principal que propicia o surgimento de bacteriobilia. O profundo conhecimento das características microbiológicas da bile nos casos de coledocolitíase e infecção das vias biliares são fundamentais para o melhor diagnóstico desta infecção e escolha da antibioticoterapia a ser instituída. Assim, o objetivo deste estudo foi de caracterizar os principais aspectos microbiológicos da bile dos pacientes com e sem coledocolitíase e avaliar sua importância na escolha dos antimicrobianos para o tratamento da infecção das vias biliares. Foram analisados 33 pacientes que foram divididos em um grupo de 10 pacientes sem coledocolitíase (grupo controle) no momento da Colangiografia Endoscópica (CPER) e em outro grupo de 23 pacientes com coledocolitíase. A bile de todos os pacientes foi coletada no início do procedimento endoscópico, através de catater introduzido na via biliar. O exame de microscopia direta com coloração de Gram e as culturas da bile foram negativas nos 10 pacientes que não apresentaram coledocolitíase durante a CPER. Dos 23 pacientes com cálculos na via biliar principal, 19 (83%) apresentaram culturas positivas. Desses 19 pacientes com culturas de bile positivas, 18 (94,7%) apresentaram microorganismos detectáveis à microscopia direta com coloração de Gram. Apenas um paciente apresentou crescimento de germe anaeróbio (Bacteroides fragilis). O cultivo de 28 bactérias teve predominância de microorganismos Gram negativos (18 bactérias- 64,3%). Os germes isolados foram E. coli (9, 32,1%), Klebsiella pneumoniae (5, 17,9%), Enterococcus faecalis (5, 17,9%), Streptococcus alfa-haemoliticus (3, 10,7%), Streptococcus viridans (2, 7,1%), Enterobacter cloacae (2, 7,1%), Panteona aglomerans (1, 3,6%) e Pseudomonas aeruginosa (1, 3,6%). Todos os pacientes com microorganismos detectados pela microscopia direta com coloração de Gram tiveram crescimento bacteriano em suas culturas, por outro lado nenhum paciente com cultura negativa apresentou microoorganismos à microsopia direta ( p= 0,0005). Nesses casos, a microsopia direta apresentou uma especificidade de 100% e sensibilidade de 80%. A análise quantitativa das culturas da bile mostrou que das 19 culturas positivas, 12 (63,2%) tiveram pelo menos um germe com contagem superior a 105 ufc/ml. Todas as bactérias Gram positivas isoladas foram sensíveis à ampicilina, da mesma forma que todas as Gram negativas foram sensíveis aos aminoglicosídeos. Os achados deste estudo demonstram uma boa correlação entre a microscopia direta da bile com coloração de Gram e os achados bacteriológicos das culturas da bile coletada por colangiografia endoscópica retrógrada. O esquema terapêutico antimicrobiano tradicionalmente empregado em nosso hospital, que inclui a combinação de ampicilina e gentamicina, parece ser adequado, pois apresenta eficácia terapêutica contra os principais microorganismos responsáveis pela infecção das vias biliares. / Acute cholangitis is an important cause of emergency admission for acute abdomen. The bacterial infection of the biliary system is associated with obstruction caused by ductal stones. Ductal obstruction leads to a raised intrabiliary pressure with bacteriobilia, cholangiovenous reflux, and bacteremia, which may progress to septicemia. We have studied the bacteriology of bile and clinical manifestations of 23 patients with choledocholithiasis and 10 patients without evidence of choledocholithiasis by endoscopic retrograde cholangiography. Nineteen (82.6%) of 23 patients with choledocholithiasis had positive bile cultures, and none of the patients without choledocholithiasis had positive bile cultures. A single microorganism was detected in 11 (57.9%) patients, while a mixed growth, with pathogens ranging from two to three species, were seen in 8 (42,1%) patients. Patients with clinical manifestations of cholangitis such as fever, abdominal pain, and jaundice (Charcot’s triad) had significant higher counts of colonies per ml of bile (p <0.001). The predominant microorganisms isolated were Escherichia coli (32,1%), Klebsiella spp. (17,9%), Enterococcus faecalis (17,9%), Streptoccus alfa-hemoliticus (10,7%), Enterobacter cloacae (7,1%), Streptococcus viridans (7,1%), Pseudomonas aeruginosa (3,6%), and Bacteroides fragilis (3,6%). In vitro susceptibility testing of the aforementioned biliary pathogens revealed ampcillin and gentamicin to have higher spectrum of antimicrobial activity. In summary, patients with choledocholithiasis have a high recovery rate of bacteria from the bile. The severity of biliary infection is associated with higher concentrations of bacteria in the choledocal bile. The data suggest that antimicrobial therapy of biliary tract infections should combine good in-vitro activity against Enterobacteriaceae (mainly Escherichia coli and Klebsiella spp.) and Enterococcus. spp. Based on the in vitro susceptibility testing of the isolated biliary pathogens, the combination of ampicillin and gentamicin seems to be an appropriate therapeutic regimen for biliary tract inferctions.

Resumo não disponível

Surface modifications of bone-interfacing biomedical devices can increase their longevity by promoting bond formation and new bone growth, while reducing the toxic effects of corrosion and wear particles. Coatings which contain biocompatible polymers, bioceramics, drugs, and functional molecules are one route to achieve this. Here, a biomimetic approach is developed for the fabrication of poly(ethyl methacrylate) (PEMA) coatings. For the first time it is shown that PEMA can be solubilized in non-toxic solvents by naturally occurring bile acids. Their unique chemical structure and amphiphilicity allows for efficient solubilization of polymer macromolecules. Advancements in colloidal sciences enable a facile deposition method termed “dip coating” to be utilized. The feasibility of highly concentrated solutions of high molecular mass PEMA was a key factor for film deposition by dip coating. Singular layers or multilayered PEMA films could be deposited. Heat-treated PEMA films provided corrosion protection to stainless steels. This inexpensive and simple technique can be up scaled to larger manufacturing levels, leading to mass production and clinical development of novel coatings for biomedical applications. Additional challenges in the fabrication of composite coatings by dip coating were successfully addressed using bile acids. To produce high quality composite coatings by dip coating, a stable suspension is required. Particle aggregation leads to uneven coatings, poor adhesion, and weakened mechanical properties. It was shown that bile acids could act as dispersing agents to mediate this. PEMA coatings containing inorganic materials hydroxyapatite, silica, titania, and diamond were fabricated. The inorganic component of the films could be increased to 50 wt.%. Model drugs tetracycline and ibuprofen were used for the creation of drug-loaded PEMA coatings. Lastly, composite coatings containing functional molecules including heparin and nanocellulose were created. Overall, these coatings provide corrosion resistance to metallic orthopedic implants, while enhancing potential biocompatibility of the device. The biomimetic approach developed in this investigation was motivated by the role of bile acids and bile salts as solubilizers of cholesterol and other molecules within the digestive system of mammals. A solubilization mechanism has been proposed. This work paves the way for the fabrication of future composite coatings containing other high molecular mass polymers, inorganic nanomaterials, and functional materials or drugs. / Thesis / Master of Applied Science (MASc) / Biomedical devices have various properties they must possess to perform their function within the body without harming the patient. Coatings applied to these devices can mitigate the body’s response by reducing corrosion, preventing wear, and promoting bond formation. This increases the lifespan of the device and prevents invasive revision surgeries. Advances in materials engineering and colloidal sciences can help achieve these goals. Materials selection for novel coatings can be inspired by the composition of real bone - consisting of a polymer matrix with embedded inorganic nanomaterials. Additionally, manufacturing techniques that avoid high temperatures are desirable. Therefore, advances in colloidal sciences which enable coatings to be fabricated by a simple and inexpensive method known as dip coating is of paramount importance. This work used natural biosurfactants bile acids to aid in fabrication of coatings for biomedical devices using advanced polymer poly(ethyl methacrylate) and functional inorganic materials.

No description available.

No description available.

Chapter 1: Amphiphilic self-assembled systems as nanocarriers Nanocarriers are the nanometric size molecular assemblies that are used for the transport of small molecules into their non-solvating environments. These systems find major applications as drug delivery systems (DDS) in pharmacological research. These drug delivery systems improves solubility and stability of the drug molecules through encapsulation and also offer additional advantages like target specificity and stimuli responsive release of the drug molecules. Several types of DDS are reported in the literature, which can be prepared by a variety of processing techniques. Of these, molecular self- Chart 1: Developments in the design of amphiphilic nanocarriers assembly has attained considerable attention due to its greater tunability and control in the preparation of nanocarriers. In this chapter we discussed about the amphiphilic nanocarriers which are prepared through self-assembly of amphiphiles through hydrophobic interactions. Several developments in the area of amphiphilic nanocarriers such as di-block polymeric systems, dendritic systems and core-shell architectures are also mentioned. We also highlighted some recent developments in the design of amphiphilic nanocarriers through supramolecular interactions and advantages of such systems. Chapter 2: Bile acid derived dendrons and their application as nanocarriers Host-guest chemistry is well known for dendritic systems. To understand the influence of steric crowding, dendritic effect and importance of number of hydroxyl groups on the bile acid backbone in the host-guest chemistry of bile acid dendrons, we designed and synthesized a new series of C3 symmetric systems and studied the above-mentioned objectives through extraction of polar dyes into nonpolar media. Dye extraction experiments performed using trimeric molecules suggested that only the cholate derivatives (3 and 4) showed considerable extraction of the polar dyes into chloroform; deoxycholate derivatives did not show any extraction, thus emphasizing the importance of the number of hydroxyl groups for dye extraction in these molecular architectures. The effect of steric crowding at the core of these trimeric molecules was shown by efficient extraction of the dyes with the triethylbenzene core (4) compared to the benzene core (3). Greater influence of the aggregates in the case of triethylbenzene core on the extracted dye was also manifested in the Chart 2: Structures of the designed molecules 1-6 value of the induced circular dichroism signal. Surprisingly, a higher analogue in these molecular architectures showed lesser efficiency in dye extraction (on a per bile acid residue basis) compared to the trimers, suggesting a more compact structure for the higher analogue. This was supported by molecular modeling studies. Generality of these systems as nanocarriers for hydrophilic dyes was investigated by screening several other dyes and polar molecules, which are diverse in their structure and functionalities. All these experiments suggested a dependency of the extraction profile on the size of the dye molecule. This was also examined by dynamic light scattering studies, which showed larger size and wider distribution in the size of the aggregates in the case of larger dyes. We also demonstrated selective extraction of a single dye molecule from a blended food color (apple green) using one of the trimer (4) and demonstrated solvent dependent morphological changes in these compounds using electron microscopy. The self-assembly of these amphilic molecules at the air-water interface was studied through Langmuir monolayer studies. Chart 3: Structure of polar guest molecules (Cresol red (7). Erioglaucine (8), Eriochrome black T (9),) phenyl β-D-glucopyranoside (10) and Eosin B (11) Chapter 3: Design and synthesis of bile acid derived surfactants: Study of their aggregation and potential applications Bile acids are facially amphiphilic systems and their amphiphilicity can be improved by attaching polar groups on the bile acid back bone or by synthesizing oligomeric systems which show better self-assembly compared to their monomeric units. To study and improve the amphiphilicity of bile acids, we designed and synthesized a new tripodal surfactant system, with a phosphine oxide based central core to which the bile acids were attached through the C-3 position using click chemistry. Our molecular design also offers added advantage of studying the influence of the stereochemistry at the C-3 position on the aggregation of these molecular architectures. We synthesized trimeric systems with both cholic and deoxycholic acids attached to the central phosphine oxide core with α and β stereochemistry at the C-3 position. Aggregation of these molecules was studied by surface tension measurements, dye extraction studies and NMR. All these compounds showed aggregation at micromolar concentrations. NMR studies suggested changes in the structure of the aggregates at higher temperature and these changes were studied by DLS, which suggested thermodynamically stable monodispersed aggregates for cholic acid derivatives (13 and 15) at higher temperature. These aggregates are stable even after cooling to room temperature and with time. The aggregates of these derivatives were also characterized by atomic force microscopy. Gelation was observed in the case of α derivatives (12 and 13) in phosphate buffer (0.1 M) at pH 7.5 for both deoxy and cholic derivatives, which emphasized the influence of stereochemistry at C-3 position in these architectures. These gels were characterized by rheology experiments. Finally, the possible utility of these micellar systems as model systems to study photophysical processes was demonstrated through lanthanide sensitization experiments in these micellar solutions. Chart 4: Structure of the designed molecules Chapter 4: Synthesis of oligomeric bile acid-taurine conjugates: Study of their aggregation and efficiency in cholesterol solubilization Bile acids are bio-surfactants that are used for the emulsification of fats, vitamins etc. in our body. Bile salts also solubilize the excess cholesterol in our body through mixed micelle formation in the bile and when the bile gets saturated with cholesterol, it leads to cholesterol gallstone formation, which needs to be treated. Ursodeoxycholic acid (UDCA) is used as drug in some cases for the solubilization of (small) cholesterol gallstones, even though the efficiency to solubilize cholesterol is less for UDCA compared to the other bile acids (UDCA is less toxic than the others). So there is a need to develop new cholesterol solubilizing agents. Since oligomeric systems can aggregate better, we designed and synthesized two tetramer taurine conjugates, which differ in the spacer between the bile acid units. Since these conjugates are not soluble in water, their solubility and aggregation was studied in 10% MeOH/Water using pyrene fluorescence experiments. Aggregation studies suggested better aggregation for these molecules compared to their monomeric analogues. These aggregates were also characterized byDLS and electron microscopy. These systems were subsequently studied as nanocarriers for liphophilic dye molecules into aqueous media. Finally, the influence of oligomeric effect in cholesterol solubilization was investigated by cholesterol solubilization studied using these two tetramer taurine compounds and a control, sodium taurocholate. These studies suggested efficient solubilization of cholesterol by oligomers compared to monomeric analogues.(For structural formula pl see the abstract file)

Chapter 1. Introduction This chapter is an overview on the literature of self-association of small organic molecules. The chapter is presented in four parts. First, an introduction to aggregation of small molecules is given with the emphasis on micelles and gels(Parts 1 and 2) In part 3, a short overview is given on bile acid based aggregates and their applications. Lastly, the content of the thesis is outlined. Chapter 2. Solution properties of novel cationic bil salts: A structure-aggregation property study Scheme 1: Structures of Cationic bile salts(Refer PDF File) Bile Salts are biosurfactants and they are known to form micelles in aqueous medium. We studied the micellar properties of cationic bile salts(Scheme 1) and compared with their natural (anionic) counterparts. A serendipitous discovery of the gelation of a cationic bile salt(4) led us to investigate the aggregation properties of this new class of cationic hydrogelators. This chapter highlights the recent efforts on the study of side chain structure-aggregation property relationship of cationic bile salts. Bile acid analogues with a quaternary ammonium group(Scheme 1, compounds 2, 3, 4, 6, 8 and 12) on the side chain were found to efficiently gel aqueous salt solutions. Some of the cationic bile salts gelled water alone and many of them gelled aqueous salt solutions even in the presence of organic co-solvents(≤ 20%) such as ethanol, methanol, DMSO and DMF. A strong counter ion dependent gelation was observed. These gels showed interconnected fibrous networks. Unlike natural anionic bile salt gels(reported for NaDC, NaLC), the cationicgels reported here are pH independent. Cationic gels derived from DCA showed more solid-like rheological response compared to natural NaDC gels studied earlier by Tato et al. A strong structure(side-chain) andcounter-ion dependent flow of the cationic bile salt gels was seen. Chapter 3. Applications of cationic bile salts and their aggregates Cationic bile salts are useful in many ways. We have studied some of the applications of cationic bile salts(discussed in chapter 2) and their aggregates in this chapter. The chapter is presented in three parts. Part 1. Interaction of Cationic bile salts and DNA The bile acid amphiphilicity is believed to help the DNA binding process of polyamines. This has prompted us to study the DNA-bile salt binding interaction of bile salts. The binding of cationic bile salts has been expressed in terms of C50 values, which were determined from the plot of fluorescence of ethidium bromide bound DNA vs. bile salt concentration(Fig 1) The C50 values for cationic bile salts were estimated to be about 1.2 mM. Fig1: A plot of fluorescene of ethidium bromide bound DNA against bile salt concentration (Refer PDF File) Part 2. Cholesterol solubilization and crystallization studies in aqueous bile salt solutions. Dihydroxy bile salt micelles are well known for cholesterol dissolution(e.g. UDCA and CDCA). We studied the dissolution of cholesterol in the cationic bile salt micelles(of 21-25) and the results are discussed in this part. Scheme 2: Cationic bile salt chlorides studied for cholesterol dissolution (Refer PDF File) A powder dissolution method was used to study the solubility of anhydrous cholesterol in cationic bile salt solution. These cationic bile salt micelles can dissolve cholesterol to the same extent as the taurine conjugates of bile acids, but lesser than the natural anionic bile salts(Fig.2) Addition of PC(Phosphatidylcholine) to cationic bile salt micelles enhanced the micellar cholesterol solubilization. Fig 2:Cholesterol dissolution in cationic bile salt solutions(Refer PDF File) The crystal nucleation time of cholesterol did not change significantly by adding 5-30 mM of the cationic bile salts. The bile salt analogues did, however, attenuate cholesterol crystallization to a similar extent at all concentrations studied. All these effects wer comparable to those fo cholic acid. Part 3. Hydrogels as a reaction vessel for photodimerization Bile salt micelles have been shown to control the product selectivity in photochemical reactions. The dynamic nature of the bile salt micelles results in differential effects on reaction selectivity. The photodimerization of acenaphthylene(sheme 3) was studied in micellar and hydrogel medium(e.g. NaDC, 22, 28, etc.) The ratio of anti- to synphotodimer was found to be greater in gel bound state than in solution. Substitution on the CAN ring did not show larger variation on the product distribution from solution gel. Scheme 3: Photodimerization of acenaphthylene(Refer PDF File) Chapter 4. Bile acid derived sulfur analogues in designing novel materials. Part 1. A simple approach towards nanoparticle-gel hybrid material. Scheme 4: Scheme for the synthesis of thiols derived from bile acids (Refer PDF File) Our interest in bile acid based gelator molecules led us to explore the synthesis and properties of bile analogues with the side chain carboxylic acid replaced by a thiol(Scheme 4) to stabilize metal NPs. We reasoned that the specific self-aggregation modes of facially amphiphilic bile units would enable a metal NP capped by such a thiol to “lock” onto a gel fiber derived from a structurally related gelator molecule. AuNPs stabilized by 38-40 were obtained by the NaBH4 reduction of homogeneous methanolic solutions of the thiol and gold salt. These steroid capped nanoparticles were found to stay dispersed in a gel of 28, thus providing a simple approach to obtain gel-nanoparticle hybrid. A photograph of the hybrid material and their morphology are shown in Fig 3.(Refer PDF File) Chart 1: Structure of the gelator used for designing a hybrid material(Refer PDF File) Part 2. Gelation of aromatic solvents using sulfur analogues of bile acid A few of the sulfur derivatives were serendipitously fouond to gel organic solvents (Fig 4). Thiol 38 formed stable gels at room temperatures while the disulphide 36 formed stable gels below 5º C. The aggregation properties, morphology, and the melting profiles of gels of disulfides and thiols derived from bile acids have been highlighted in this part. Fig 4: A photograph of the gels derived from 38(Refer PDF File) (For Figures and Molecular Formula Pl refer the Original Thesis)