Nanoparticles as an emerging tool to alter the gene expression: Preparation and conjugation methods

Many human diseases occur due to the over or under-expression of genes which can be corrected either by silencing or over-expression, respectively by transforming with specific nucleic acid (NA). NA transformation for medical purposes to alter the cellular gene expression is challenging because NA cannot cross efficiently the cellular biomembrane. One option, the viral vectors, is risky for patients and, the non-viral vectors have lower transformation efficiency. From the past few years, nanoparticles (NPs) are being studied extensively for their use as a vector to deliver NA. They are of a sub-micron size, have a large surface area, rapid absorption ability and can reach inside of the cells. These properties make them a suitable gene carrier. NPs types - organic, inorganic, organic/inorganic hybrid and polymeric NPs, having different properties that can be used to deliver the NA. They possess various properties like biocompatibility, targeted delivery of gene, controlled release of NA which makes them suitable for different uses. In this review, we are describing and comparing various methods to synthesize various kinds of NPs and how they can be conjugated with NA. A series of modifications in NPs to form the polyplex are also discussed along with the varying outcomes in terms of changes in the gene expression and its cytotoxicity towards different cell lines. This review is helpful for nano-scientists to decide which method to be followed for a specific need via controlling gene expression.