Anticancer drugs targeted therapy through the blood-brain barrier: drug, chemical modification or nanoparticles. Quite small and carrier size, which limits the number of modified nano-carrier molecules, making it difficult to achieve the appropriate combination balance. Adsorption-mediated endocytosis also becomes a hot topic, including the electrostatic interaction between the negatively charged cell membrane and positively charged ligands at the BBB (mainly sialic acid). The carrier-mediated transporter system, including glucose transporter 1, has been studied. It was shown that liposome surface parcels coated with mannose, but not B a mannose derivative, can induce transport across the BBB. Cation transporter-mediated choline derivatives coated nanoparticles are transported by brain-derived endothelial cells faster than uncoated nanoparticles, possibly due to the lipophilic nature of choline derivatives. The BBB-specific expression of folate receptor transporter can be surface-modified by folic acid flexible multi-star nanoparticles. Some hydrophilic surfactants, especially Tween class, interact with the BBB surface. Tween flexible multi-coated nanoparticles show more potential for drug transit to the brain compared to PEG-coated nanoparticles. Surfactant toxicity, non-biocompatibility, and increased BBB permeability causing destruction of tight junctions are important issues.
3 Conclusion: Several strategies can improve the ability of anticancer drugs to penetrate the BBB: (1) fat-soluble drugs by passive diffusion, limited to small molecules; (2) the development of prodrugs to bypass the BBB transporter mechanism, but the high selectivity of the transport mechanism limits this strategy; (3) the development of drug-loaded nanocarriers that can disrupt the tumor BBB. Treating brain tumors with nanoparticles holds the most potential for drug delivery. Minimally invasive and highly selective strategies for drug delivery to brain tumors must take advantage of physiological and permeability differences. Colloidal systems (nanoparticles) through modification can enhance brain targeting, improving drug efficacy while reducing adverse reactions. Development-related technical issues include the complexity of nanoparticle preparation and targeted nanoparticles, increasing the risk of adverse reactions; advantages include increased drug reaching the target and selective enhancement, and the possibility of multiple drugs reaching the same position. Creating a molecular toolbox to effectively wrap drugs and deliver them to brain tumors is necessary, assembling molecular-level structures into controllable ordered configurations. Multifunctional delivery vectors must contain positively charged (cationic) components to enhance vascular uptake, vascular targeting, and intercellular transport of reagents and drugs. Achieving the effectiveness and selectivity of nano carriers capable of carrying anticancer drugs is a very complex entity. Nanocarriers can wrap anticancer drugs in a polymer film layer core, have BBB-targeting molecules on their surface, enhance transporter molecular modifications, carry enough positive charge to increase brain tumor vascular intake, and also inhibit BBB and multi-drug resistance mechanisms produced by tumor cells. Therefore, the ideal target brain tumor treatment drug nanoparticle delivery system (Figure 2) has the following characteristics: (1) selective targeting of BBB lesions; (2) contains partial hydrolyzable key efflux pump inhibitors; (3) transports drugs through the brain vascular system and transfers them to the target, which is brain tumor cells. Nanosystems with this diversity require a better understanding of the biophysical mechanisms of interaction between nanoparticles and living organisms, biochemical mechanisms, and physiological mechanisms. Challenges include changes in clear brain tumor and disease-related BBB properties; modification of drugs or drug carriers as targeting agents and transit enhancers. Antibodies are selective, but their size and potential immunogenicity limit their spread and use in tissues, such as Tf and its receptor, presenting similar problems. The most promising vectors are small molecules that can be used as BBB targeting agents and transit enhancers, stable in physiological medium, easy to synthesize in large quantities with high drug loading. However, a generic design uniquely applicable in various environments and purposes for targeting vectors is unrealistic.
The agent, blood drying Shao boots, improves selection: Tian pickled Yi transport enhancer, mouth BBB transporter + ~ II R inhibitors: hydrolysis in order to reduce the drugs' efflux across the BBB from the endothelial cells. Figure 2 shows the structure model of the nanoparticle delivery system compiled from Juillerat-JeanneretL,. The targeted delivery of cancer drugs across the blood-brain barrier: chemical modifications of drugs or drug-nanoparticles? [J]. Drug Discov Today, 2008,13 (23/24):1099-1106.