Hyperbranched Silicone MDTQ Tack Promoters.

Low molecular weight, highly crosslinked silicone resins are widely used as reinforcing agents for highly transparent elastomers and adhesion/tack promoters in gels. The resins are complex mixtures and their structure / property relationships are ill defined. We report the synthesis of a library of 2, 3 and 4-fold hyperbranched polymeric oils that are comprised of linear, lightly branched or highly branched dendronic structures. Rheological examination of the fluids and tack measurements of gels filled with 10, 25 or 50% dendronic oils were made. Viscosity of the hyperbranched oils themselves was related to molecular weight, but more significantly to branch density. The properties are driven by chain entanglement. When cured into a silicone gel, less densely branched materials were more effective in improving tack than either linear oils or Me3SiO-rich, very highly branched oils of comparable molecular weight, because the latter oils underwent phase separation.

Thiolated silicone oil: synthesis, gelling and mucoadhesive properties.

The aim of this study was the development of novel thiolated silicone oils and their evaluation with regard to gelling and mucoadhesive properties. A thiol coupling of 220 ± 14 and 127 ± 33 µmol/g polymer for 3-mercaptopropionic acid (MPA)- and cysteine-coupled silicone oil was determined, respectively. The dynamic viscosity of MPA-silicone raised significantly (p<0.000001) after oxidation with iodine to a maximum of 523-fold within 1h. During tensile studies, MPA-silicone showed both the highest results for total work of adhesion (TWA) and maximum detachment force (MDF) with a 3.8- and 3.4-fold increase, respectively, compared to the control. As far as the residence time on small intestinal mucosa is concerned, both silicone conjugates were detectable in almost the same quantities for up to 8h with 56.9 ± 3.3 and 47.8 ± 8.9% of the initially applied conjugated silicone oil. Thiolated silicone oils can be regarded superior in comparison to commonly used silicone oils due to a prolonged retention time in the small intestine as site of action. Gelling and mucoadhesive features are advantageous for antiflatulent as well as mucoprotective biomaterials. Thus, these novel thiomers seem promising for an upgrade of currently available products for the treatment of dyspepsia, reflux oesophagitis and even inflammatory bowel diseases such as ulcerative colitis or Crohn's disease.

Uniform-sized silicone oil microemulsions: preparation, investigation of stability and deposition on hair surface.

Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 µm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 µm. The uniform-sized microemulsion of 40.0 µm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner.

Development of biotechnology products in pre-filled syringes: technical considerations and approaches.

A monoclonal antibody (mAb) product development case study is presented to address some of the issues faced during developing a pre-filled syringe (PFS) product for a biotherapeutic. In particular, issues involving incompatibility with silicone oil and a stability-based approach for selection of PFS barrel and tip cap components have been discussed. Silicone spiking studies followed by exposure to agitation stress or accelerated temperature conditions were used to check for incompatibilities of the mAb with silicone oil, a necessary product contact material in PFS. In addition, screening studies to compare various closure materials as well as syringe barrel processing methods were used to select the optimum closure materials as well as the correct syringe processing method. Results indicate that the model mAb formulation used was sensitive to high levels of silicone oil especially under accelerated temperature conditions resulting in formation of protein-silicone particles in the solution for samples that were spiked with the silicone oil. Agitation stress did not have any significant impact on the quality attributes tested. Samples stored in syringe barrels that were processed with sprayed-on silicone had higher levels of subvisible particles as compared to those that were processed with the baked-on process. The tip cap comparability study resulted in one tip cap material having superior compatibility among the three that were tested. The quality attribute that was most impacted by the tip cap materials was mAb oxidation. An approach for evaluation of primary packaging components during the development of pre-filled syringe presentations for biotechnology-based compounds has been highlighted.