Wayne Cummins

Serum response to supplemental macular carotenoids in subjects with and without age-related macular degeneration.

Macular pigment (MP) is composed of lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ). The present study reports on serum response to three different MP supplements in normal subjects (n 27) and in subjects with age-related macular degeneration (AMD) (n 27). Subjects were randomly assigned to: Group 1 (20 mg L and 2 mg Z), Group 2 (10 mg L, 2 mg Z and 10 mg MZ) or Group 3 (3 mg L, 2 mg Z and 17 mg MZ). Serum carotenoids were quantified at baseline, and at 4 and 8 weeks using HPLC. Response data for normal and AMD subjects were comparable and therefore combined for analysis. We report response as the average of the 4- and 8-week concentrations (saturation plateau). Serum L increased significantly in Group 1 (0·036 μmol/l per mg (269 %); P< 0·001) and Group 2 (0·079 μmol/l per mg (340 %); P< 0·001), with no significant change in Group 3 (0·006 μmol/l per mg (7 %); P= 0·466). Serum Z increased significantly in Group 1 (0·037 μmol/l per mg (69 %); P= 0·001) and Group 2 (0·015 μmol/l per mg (75 %); P< 0·001), with no significant change in Group 3 ( − 0·0002 μmol/l per mg ( − 6 %); P= 0·384). Serum MZ increased significantly in Group 1 (0·0094 μmol/l (absolute value); P= 0·015), Group 2 (0·005 μmol/l per mg; P< 0·001) and Group 3 (0·004 μmol/l per mg; P< 0·001). The formulation containing all three macular carotenoids (Group 2 supplement) was the most efficacious in terms of achieving the highest combined concentration of the three MP constituent carotenoids in serum, thereby potentially optimising the bioavailability of these compounds for capture by the target tissue (retina).

Synthesis of mucoadhesive thiolated gelatin using a two-step reaction process

Using a novel two-step approach, the thiolation of gelatin for mucoadhesive drug delivery has been achieved. The initial step involved the amination of native gelatin via an amine to carboxylic acid coupling reaction with ethylene diamine, followed by thiolation with Trauts reagent. The resulting thiolated product showed an increase in thiol content of up to 10-fold in comparison with control gelatin samples. Improved cohesion and mucoadhesion in comparison with unmodified and control gelatin samples was also observed. This reaction process was observed to be influenced by both the temperature and the pH of the amination reaction, affecting both amine content and product yield. Swelling ability, cohesion and mucoadhesion were all observed to be strongly dependent on the thiol content of the samples but also, importantly, the molecular weight (MW) of the gelatin used. Gelatin with a MW of 20-25 kDa proved to be optimal in creating this novel mucoadhesive gelatin material.

Thermal desorption characterisation of molecularly imprinted polymers. Part I: a novel study using direct-probe GC-MS analysis

A novel thermal desorption technique using a direct-probe device (Chromatoprobe) attached to a gas chromatograph–mass spectrometer is presented for the thermal pretreatment, characterisation and analysis of molecularly imprinted polymers. The technique is demonstrated as effective for the removal of volatile materials, including template and unreacted monomers, from methacrylic acid–ethylene glycol dimethacrylate copolymers imprinted with 2-aminopyridine. Mass spectrometry is a powerful technique for polymer bleed characterisation. Thermal desorption studies on reloaded template and related compounds are reported as a means of assessing polymer morphology, specific binding by imprinted polymers compared with reference non-imprinted polymers and selective binding by an imprinted polymer for its template. Calibration studies on the thermal desorption technique using an internal standard are presented with R2 > 0.999. The technique provides a novel method for assessment of polymer thermal stability, composition and morphology.

Thiolated polymers as mucoadhesive drug delivery systems

&NA; Mucoadhesion is the process of binding a material to the mucosal layer of the body. Utilising both natural and synthetic polymers, mucoadhesive drug delivery is a method of controlled drug release which allows for intimate contact between the polymer and a target tissue. It has the potential to increase bioavailability, decrease potential side effects and offer protection to more sensitive drugs such as proteins and peptide based drugs. The thiolation of polymers has, in the last number of years, come to the fore of mucoadhesive drug delivery, markedly improving mucoadhesion due to the introduction of free thiol groups onto the polymer backbone while also offering a more cohesive polymeric matrix for the slower and more controlled release of drug. This review explores the concept of mucoadhesion and the recent advances in both the polymers and the methods of thiolation used in the synthesis of mucoadhesive drug delivery devices. Graphical abstract Figure. No caption available.

Thermal desorption characterisation of molecularly imprinted polymers. Part II: Use of direct probe GC–MS analysis to study crosslinking effects

A powerful method utilising direct probe thermal desorption GC–MS is presented for the study of molecularly imprinted polymers (MIPs). A series of 2-aminopyridine (2-apy)-imprinted methacrylic acid–ethyleneglycol dimethacrylate (MAA–EGDMA) copolymers were prepared under identical conditions but with varying amounts of EGDMA (crosslinking monomer). The use of appropriate temperature programmes permitted template removal, and the subsequent assessment of polymer affinity and specificity, all of which were found to be dependent on polymer composition and morphology. The system was sufficiently sensitive to identify a specific response of imprinted polymers over nonimprinted counterparts. Correlations were found to exist between thermal desorption analysis and solution phase binding, which was assessed by UV spectroscopy, where specificity was found to diminish with decreasing EGDMA concentration. This was attributed to the increased number of free carboxyl groups in those polymers containing a lower percentage of EGDMA. Thermal desorption profiles obtained for the analyte were found to be unaffected by the physical and chemical properties of the solvent used for analyte reloading.

Dispersive Liquid-Liquid Microextraction in the Analysis of Milk and Dairy Products: A Review

Dispersive liquid-liquid microextraction (DLLME) is an extraction technique developed within the last decade, which involves the dispersion of fine droplets of extraction solvent in an aqueous sample. Partitioning of analytes into the extraction phase is instantaneous due to the very high collective surface area of the droplets. This leads to very high enrichment factors and very low solvent consumption, relative to other liquid or solid phase extraction methods. A comprehensive review of the various modes of DLLME in the analysis of organic and inorganic analytes in dairy products (milk, cheese, infant formula, yogurt, and breast milk) is presented here. Dairy products present a complex sample matrix and the removal of interfering matrix components can prove troublesome. This review focuses on sample pretreatment prior to the appropriate DLLME procedure, the extraction and dispersive solvents chosen, derivatisation methods, and analytical figures of merit. Where possible, a critical comparison of DLLME methods has been undertaken. The overall suitability, and limitations, of DLLME as a sample preparation technique for dairy products has been assessed.

Comparison of the mucoadhesive properties of thiolated polyacrylic acid to thiolated polyallylamine.

Synthetic polymers, polyacrylic acid (PAA) and polyallylamine (PAAm), were thiolated using different methods of thiolation. Both polymers resulted in comparable thiol contents, thus allowing for the direct comparison of mucoadhesive and cohesive properties between the well-established thiolated PAA and the more novel thiolated PAAm. Thiolation of both polymers improved the swelling ability and the cohesive and mucoadhesive properties in comparison to unmodified control samples. In this study, it was shown that the swelling abilities of the thiolated PAAm sample were far greater than that of the thiolated PAA sample which, in turn, affected the drug release profile of the thiolated PAAm sample. Importantly, however, the mucoadhesive properties of thiolated PAAm were equivalent to that of the thiolated PAA sample as demonstrated by both the adhesion times on porcine intestinal tissue as measured by the rotating cylinder method and by rheological studies with a mucin solution. This study demonstrates the potential thiolated polyallylamine has as a mucoadhesive drug delivery device.

The application of dispersive liquid–liquid microextraction in the analyses of the fatty acid profile in bovine milk in response to changes in body condition score

Dispersive liquid-liquid microextraction (DLLME) was used prior to gas chromatography flame ionization detection (GC-FID) for the extraction of five fatty acids from milk taken from cows with different body condition scores. Optimum extraction conditions were: 300 μL of chloroform (extraction solvent), and 1 mL methanol (dispersive solvent). The procedure was optimised using Design of Experiments (DoE). The analytes were separated on a GC capillary column containing a polyethylene glycol stationary phase (15 m × 0.53 mm × 1.2 μm). Enrichment factors were in the range of 8-15 and limit of detection (LOD) was 0.04 μg/mL. Calibration graphs showed good linearity with coefficients of determination higher than 0.994% and relative standard deviations lower than 7%. This method provided a simple and rapid derivatisation and extraction method for the determination of fatty acids in bovine milk. It showed that there was a significant difference in the palmitic acid content of milk from cows that had an optimum body condition score (10.85 mg/mL) compared to cows that had a high body condition score (5.73 mg/mL).

Effect of seaweed supplementation on tocopherol concentrations in bovine milk using dispersive liquid-liquid microextraction

A dispersive liquid-liquid microextraction (DLLME) method, combined with HPLC-UV detection, was developed for the extraction and preconcentration of δ-tocopherol from bovine milk. This method was used to study the effect of supplementing cow feed with the seaweed Ascophyllum nodosum on vitamin content in milk. The optimal experimental conditions were determined: 200 μL of chloroform (extraction solvent), 1.0 mL of ethanol (dispersive solvent), 5 mL of water (aqueous phase). Under these optimal conditions the DLLME method provided linearity in the range 0.01 μg/mL to 8 μg/mL with R2 values of 0.998. Limit of detection (LOD) was 0.01 μg/mL, while the enrichment factor was 89. Cow feed that was supplemented with Ascophyllum nodosum was shown to increase δ-tocopherol levels from 3.82 μg/mL to 5.96 μg/mL.