Nanomedicine Delivery With Molecular Dynamics Simulation

Nano-medicines are currently the hotspot of research.Due to its special size effect and surface effect,compared with common medicines,it has the advantages of strong penetrating ability,good targeting,and high catalytic efficiency,which have important applications in the field of biomedicine.In recent years,with the rapid development of nanotechnology,a variety of clinical treatments have adopted nano-medicines such as respiratory therapy.Respiratory therapy usually means that nano-medicines enter the lungs through the respiratory tract,and then participate in the internal circulation,which has a greater advantage than systemic administration.Nano-medicines will interact with pulmonary surfactants first when they enter the alveoli via the respiratory tract.Pulmonary surfactant is the first biological barrier for nano-medicines to enter the human body through the lungs and directly determines the final destination of nano-medicines.Therefore,understanding the interaction between nano-medicines and pulmonary surfactants will contribute to the development of nano-medicines in respiratory therapy.At the present stage,the continuous improvement of computational methods enables multiple fields to simulate the trajectory of atoms or molecules through computers,so as to achieve quantitative or qualitative observation of research objectives.The main task of this paper is to simulate the interaction between nano-medicines and pulmonary surfactants by computer,while nano-medicines mainly use rigid nano-particles as drug carriers,and pulmonary surfactants are a kind of phospholipid monolayers that mainly are composed of different phospholipids in a certain proportion.Therefore,in order to simplify the research process,this article uses coarse-grained molecular dynamics research methods for simulation experiments,with rigid nano-particles as nano-medicines and phospholipid monolayers as pulmonary surfactants.The research summarized as follows:1.Different sizes of nanoparticles on the role of phospholipid monolayersSize is one of the most concerned properties in nanoparticle research.At present,there are many researches on nanoparticle size in various fields.However,most of them focus on the transmembrane performance of nanoparticle.And there is still a lack of systematic and comprehensive theoretical research.Based on this problem,the molecular dynamics simulation method is used to study the size effect of nanoparticles crossing the monolayer of phospholipid.The simulation results show that different sizes of hydrophilic nanoparticles can cross the phospholipid monolayer,but have different effects on the monolayer structure and normal phase transition of phospholipid.The larger the size,the more obvious the influence is.At the same time,the size of the nanoparticles affects the time it takes to cross the phospholipid monolayer,which is that the larger size,longer transmembrane time is.In general,small size nanoparticles are more suitable as nano-medicine carriers.2.Different surface properties of nanoparticles on the role of phospholipid monolayersThe biological study of the surface properties of nanoparticles also plays a crucial role in the interaction between nanoparticles and phospholipid monolayers,such as hydrophobicity and surface charge.Hydrophobicity and surface charge have been studied for a long time.Based on this,we simulate the interaction of nanoparticles with different surface properties on a single molecule of phospholipid,including the different surface charge density of nanoparticles and the different surface charge positions of nanoparticles.The simulation results show that both the surface charge density and surface charge of nanoparticle can affect the nanoparticle's ability to cross the phospholipid monolayer.On the one hand,the surface charge density of nanoparticles influences the transmembrane results and the structure and normal phase transition of the phospholipid monolayer,which is that the greater the surface charge density of nanoparticles,the worse the transmembrane ability,the longer the transmembrane time and the greater the perturbation of the monolayer.At the same time,the charged nanoparticle can be adsorbed on the surface of the phospholipid monolayer,and this adsorption ability will gradually become stronger as the surface charge density of the nanoparticle increases.On the other hand,nanoparticle charged in the face-centered position has better transmembrane capacity,while the nanoparticle charged at the edge position has a lower transmembrane capacity,which is not related to the positive or negative charge of the nanoparticle.Moreover,compared with negatively charged nanoparticles,positively charged nanoparticles more easily adsorbed on the phospholipid monolayer.The results of these simulations can explain some experimental phenomena well and have important implications for the development of nano-medicine.In this paper,the interaction between nanoparticles and phospholipid monolayers is simulated to study the transmission of nano-medicines in the lung.The results of the study can better understand the bio-safety of nanoparticle as a nano-medicine carrier and promote their more effective application in the field of biomedicine.