ABSTRACT
The complexity of tumor microenvironment brings both challenges and opportunities for targeted drug delivery. On the one hand, using the special characteristic as stimuli, we can construct a variety of responsive drug delivery systems for tumor targeting. On the other hand, the abnormal vasculature and dense extracellular matrix in solid tumor become formidable barriers to the nanoparticles delivery, which greatly reduces the drug delivery efficiency. Lots of researches focus on regulating the tumor microenvironment to make it more conducive to drug delivery. In this review, we will highlight the recent advances both in tumor microenvironment responsive nano-drug delivery systems design and tumor microenvironment regulation to improve tumor targeted delivery efficiency, and discuss the existing problems and future development.
ABSTRACT
DNA hydrogels,combining the features of both DNA and hydrogels macromolecules,are endowed with the biologi?cal characters of DNA and the framed structure of hydrogels skeleton.Currently,most DNA hydrogels can achieve sensitive response to temperature,pH,light,and small molecule stimuli,by introducing specific groups or sequences into their backbone.Therefore, the functional properties of DNA hydrogels can be further improved.In this review,we introduce the mentioned stimuli-response DNA hydrogels,as well as their applications in drug controlled-releasing,targeted cancer therapy,biosensor and others.Finally,the pros?pects in the development of DNA hydrogels are also mentioned.
ABSTRACT
Stimuli-responsive nano drug delivery systems based on specific structures and physicochemical properties of tumor have been drawing wide attention from researchers, one of which is charge-reversal nano drug delivery system(CRN-DDS). CRN-DDS can effectively combine the merits of positive and negative charges in the drug delivery process in vivo, and it also has the good property of tumor-targeting. Although studies of CRN-DDS application in cancer therapy have already been reported, there is very little relevant Chinese literature, especially review articles. To fill in the blank, the foreign literatures about CRN-DDS were looked up in the last six years, classified CRN-DDSs by their different approaches of surface charge reversal, and summarized the studies on their applications in the cancer therapy. Last but not least, the prospect of CRN-DDS's development and application was preliminarily looked into in this article.
ABSTRACT
Nanocrystals are pure drug crystals with sizes in the nanometer range. Due to the advantages of high drug loading, platform stability, and ease of scaling-up, nanocrystals have been widely used to deliver poorly water-soluble drugs. Nanocrystals in the blood stream can be recognized and sequestered as exogenous materials by mononuclear phagocytic system (MPS) cells, leading to passive accumulation in MPS-rich organs, such as liver, spleen and lung. Particle size, morphology and surface modification affect the biodistribution of nanocrystals. Ligand conjugation and stimuli-responsive polymers can also be used to target nanocrystals to specific pathogenic sites. In this review, the progress on injected nanocrystals for targeted drug delivery is discussed following a brief introduction to nanocrystal preparation methods, i.e., top-down and bottom-up technologies.