2 research outputs found
Rapid and Accurate Quantification of Viable <i>Lactobacillus</i> Cells in Infant Formula by Flow Cytometry Combined with Propidium Monoazide and Signal-Enhanced Fluorescence In Situ Hybridization
Lactobacillus is an important member
of the probiotic
bacterial family for regulating human intestinal microflora and preserving
its normalcy, and it has been widely used in infant formula. An appropriate
and feasible method to quantify viable Lactobacilli cells is urgently required to evaluate the quality of probiotic-fortified
infant formula. This study presents a rapid and accurate method to
count viable Lactobacilli cells in infant formula
using flow cytometry (FCM). First, Lactobacillus cells
were specifically and rapidly stained by oligonucleotide probes based
on a signal-enhanced fluorescence in situ hybridization (SEFISH) technique.
A DNA-binding fluorescent probe, propidium monoazide (PMA), was then
used to accurately recognize viable Lactobacillus cells. The entire process of this newly developed PMA-SEFISH-FCM
method was accomplished within 2.5 h, which included pretreatment,
dual staining, and FCM analysis; thus, this method showed considerably
shorter time-to-results than other rapid methods. This method also
demonstrated a good linear correlation (R2 = 0.9994) with the traditional plate-based method with a bacterial
recovery rate of 91.24%. To the best of our knowledge, the present
study is the first report of FCM combined with PMA and FISH for the
specific detection of viable bacterial cells
Multistage Anticoagulant Surfaces: A Synergistic Combination of Protein Resistance, Fibrinolysis, and Endothelialization
Anticoagulant
surface modification of blood-contacting materials
has been shown to be effective in preventing thrombosis and reducing
the dose of anticoagulant drugs that patients take. However, commercially
available anticoagulant coatings, that is, both bioinert and bioactive
coatings, are typically based on a single anticoagulation strategy.
This puts the anticoagulation function of the coating at risk of failure
during long-term use. Considering the several pathways of the human
coagulation system, the synergy of multiple anticoagulation theories
may provide separate, targeted effects at different stages of thrombosis.
Based on this presumption, in this work, negatively charged poly(sodium p-styrenesulfonate-co-oligo(ethylene glycol)
methyl ether methacrylate) and positively charged poly(lysine-co-1-adamantan-1-ylmethyl methacrylate) were synthesized
to construct matrix layers on the substrate by electrostatic layer-by-layer
self-assembly (LBL). Amino-functionalized β-cyclodextrin (β-CD-PEI)
was subsequently immobilized on the surface by host–guest interactions,
and heparin was grafted. By adjusting the content of poly(oligo(ethylene
glycol) methyl ether methacrylate) (POEGMA), the interactions between
modified surfaces and plasma proteins/cells were regulated. This multistage
anticoagulant surface exhibits inertness at the initial stage of implantation,
resisting nonspecific protein adsorption (POEGMA). When coagulation
reactions occur, heparin exerts its active anticoagulant function
in a timely manner, blocking the pathway of thrombosis. If thrombus
formation is inevitable, lysine can play a fibrinolytic role in dissolving
fibrin clots. Finally, during implantation, endothelial cells continue
to adhere and proliferate on the surface, forming an endothelial layer,
which meets the blood compatibility requirements. This method provides
a new approach to construct a multistage anticoagulant surface for
blood-contacting materials