Recently, numerous attempts have been made to evaluate the potential of chitosan as an adjuvant; however, few have explored the mechanism underlying the adjuvant activity of chitosan.
Food safety is one of the major concerns for consumers all around the world. Here in this work, we present a method that can be used for direct onsite fast screening of illicit additives on fruit peel. The method is based on our newly developed poly(vinyl alcohol) (PVA) hydrogel (slime) SERS substrate, which can conform to any surface shape. Simply by applying the hydrogel SERS substrate on the surface of interest, the limit of quantification for Sudan red (SR) III on a glass surface was found to be 1.6 ng/4 cm 2 . The time decay of SR III on a spiked kumquat was monitored with the proposed hydrogel SERS method and verified by HPLC. It was found that even after 25 days since dying, SR III could still be clearly identified at a level of dozens of ppb. With virtually no sample preparation requirement, the whole analysis procedure only took less than 5 min. Thus, the hydrogel SERS substrate based method could be used for future onsite food quality assurance applications when combined with a portable Raman spectrometer.
Recombinant protein vaccines, with highly pure ingredients and good safety, are gradually replacing some attenuated and inactivated vaccines in clinical practice. However, since their low immunogenicity of the recombinant proteins, adjuvants are often needed to enhance immune response after vaccination. Aluminum adjuvant has been widely used in some vaccines for decades, it can induce strong humoral immunity, but the deficiency of cellular immunity limits its application for some vaccines. Therefore, it is urgently needed to develop novel adjuvant to increase not only humoral but also cellular immune response. To address this, we designed and prepared a new nano adjuvant (PF3) through microfluidization by the combination of saponin (Ginsenoside Rg1) and oil-in-water nano emulsion (NE) in the present study. As compared to aluminum adjuvant, PF3 had stronger humoral and cellular immune induction effect because of high cellular uptake and activization of immune response pathways. Furthermore, PF3 showed better immune enhancement and acceptable biosafety equivalent to that of aluminum adjuvant. In addition, no obvious changes of PF3 were observed in size and zeta potential after 12 weeks storage at 4 and 37°C, demonstrating its high stability in vitro. This study provided an adjuvant platform to replace traditional aluminum adjuvant in design of recombinant vaccines.
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