Assessment of Functional and Physical Performances of Pre-filled Syringes in Deep Cold Storage Conditions.

The recent emergence of new drug technologies such as messenger ribonucleic acid-based vaccines developed to fight the outbreak of the COVID-19 global pandemic has driven increased demand for delivery solutions capable of withstanding deep cold storage conditions down to -50°C, and even down to -80°C. Although significant data exist for deep cold storage in vials, little evidence is available for pre-filled syringes. Because pre-filled syringes serve as both the storage container and the delivery mechanism, there are additional risks to performance that must be evaluated, such as plunger gliding performance, syringe lubrication, silicone layer stability, and container closure integrity (CCI). In the present study, a comprehensive assessment of functional and physical performances of pre-filled syringes (PFS filled with water) was performed after one or multiple freeze/thaw (F/T) cycles between ambient temperature and various temperature cycles including -40°C, -50°C or -80°C for both 'staked needle' and 'luer lock' configurations. The experiments were guided by historical normative methods such as ISO 11040-4 and USP <1207> and combined with headspace gas analysis for barrel-stopper tightness testing. In addition, they were complemented with a novel approach, namely in situ real-time optical imagery, to track plunger stopper movement during the F/T cycle. The findings indicated that there is no significant impact on the functional performances from F/T down to -80°C, whereas no CCI risk was found after F/T down to -50°C.

Multiple welding of long fiber epoxy vitrimer composites.

Vitrimers appear as a new class of polymers that exhibit mechanical strength and are insoluble even at high temperatures, like thermosets, and yet, like thermoplastics, they are heat processable, recyclable and weldable. The question arises whether this welding property is maintained in composite materials made of more than 50 vol% of reinforcing fibers. In this paper, we quantitatively analyze the bond strength of epoxy vitrimer-based composite plates made by resin transfer molding and compare them to their non-vitrimer counterparts made of a standard thermoset epoxy. It is demonstrated that only epoxy vitrimer samples show substantial bond strength and the ability to be repeatedly welded thanks to the exchange reactions, which promote improved surface conformity and chemical bonding between the adherands at the joint interface. This opens the way towards joining composite parts without adhesives nor mechanical fasteners.