Adsorption And Interaction Of Nano-micro Particles On Membrane Surfaces

In the environment around us,there are various particles,such as micro-scale atmospheric particles and nano-scale synthetic particles.The impact of partilces on the human health has attracted a lot of attention.In this paper,fly ash particles and gold nanorods（GNRs）were selected as the typical representatives of nano-micro particles.Their adsorption behaviors on protein membranes or model cell membrane as well as their interaction characteristics were studied using a few spectroscopic methods and a quartz crystal microbalance with a dissipation monitor（QCM-D）.The main contents are shown as follows.（1）Component analysis of fly ash particles and their behaviors in protein solutions.Fly ash particles can contribute to haze and adverse health outcomes.The dispersion and sedimentation behaviors of fly ash particles in protein solutions were studied to analyse their relationship with health hazards.In the experiment,two mucins（BSM,PGM）and bovine serum albumin（BSA）served as model proteins.Fly ash powders were provided by a local municipal waste incineration plant and the average particle size of fly ash particles was 9.35±0.97μm.Furthermore,the particles contained high concentrations of Fe,Zn and Pb ions,which were at harmful levels.The sedimentation rate of fly ash particles in Milli-Q water was faster than that in mucin solutions and it was slowest in BSA solution.Moreover,the proportion of small particle size of fly ash particles in mucin and BSA solutions increased significantly.Thses results indicited that mucins and BSA dispersed the fly ash particles and they may promote particles to transport to the remote body part,which may cause health hazards.（2）Adsorption behaviors and interaction characteristics of fly ash particles with proteins.Interaction and adsorption behavior studies revealed the toxicity and health hazards of fly ash particles,which further provided health risk warning.The interaction characteristics between fly ash particles and three kinds of protein solutions were investigated by combining several spectroscopic techniques.The results indicated that the fly ash particles could induce the loosening of mucins and BSA.Furthermore,theα-helix content decreased with increasing fly ash particle concentrations.Addition of fly ash particles into protein solutions led to fluorescence quenching.These results suggested that there were interactions between fly ash particles and mucins as well as BSA.The association constants（K_a）for BSM and BSA were 5.35 L/g and 4.18 L/g,respectively.In addition,the results of QCM-D analyses showed that the masses decreased on the mucin membrane surfaces but increased slightly on the BSA membrane surface with the injection of fly ash particles,which indicated that the fly ash particles disrupted the mucin membranes.（3）Real-time adsorption behaviors of gold nanorods on model cell me mbrane.Gold nanorods（GN Rs）exhibit promising potentials in therapeutics and diagnostics.The study of interaction between GN Rs and model cell membranes provided a comprehensive and systematic understanding of their interactions,which guided applications of GN Rs to some extent.Supported lipid bilayers（SLBs）comprising zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine（DOPC）modified on chip surface were used as the model cell membrane.QCM-D results showed that the adsorption masses of GN Rs on DOPC SLBs increased with increasing GNRs concentrations.The GNRs with smaller size exhibited a higher deposition mass in comparison with the larger one when they had a similar zeta potential.Under neutral p H conditions,the adsorption masses and rates of GNRs on SLBs increased with increasing concentrations of Na⁺（from 10 m M to 1 M）and Ca²⁺（from 0.1 to 0.5 m M）.However,the adsorption masses and rates decreased with further increase in Ca²⁺concentrations from 0.5 to 10 m M.Additionally,p H also influenced the deposition behavior of GNRs on SLBs because of the change in their electrostatic interaction.Furthermore,a possible mechanism was proposed based on the experimental results.The repulsive hydration force was probably reduced at high concentrations of Na⁺and more GNRs were adsorbed on DOPC SLBs.However,in the presence of high concentrations of Ca²⁺,the GN Rs aggregation and electrostatic repulsion between GNRs and SLBs which may occur due to the charge reversal of SLBs resulted in low adsorption mass.