The meaning of gene therapy is the delivery of DNA or RNA to cells for the treatment or prevention of genetic disorders. The success rate of gene therapy depends on the progression and safe gene delivery system. The vectors available for gene therapy are divided into viral and non-viral systems. Viral vectors cause higher transmission efficiency and long gene expression, but they have major problems, such as immunogenicity, carcinogenicity, the inability to transfer large size genes and high costs. Non-viral gene transfer vectors have attracted more attention because they exhibit less toxicity and the ability to transfer large size genes. However, the clinical application of non-viral methods still faces some limitations, including low transmission efficiency and poor gene expression. In recent years, numerous methods and gene-carriers have been developed to improve gene transfer efficiency. The use of Polyethylenimine (PEI) based transfer of collaboration may create a new way of treating diseases and the combination of chemotherapy and gene therapy. The purpose of this paper is to introduce the PEI as an appropriate vector for the effective gene delivery.

Development of biologically inspired green synthesis of silver nanoparticles has attracted considerable worldwide attention in matter of medical science and disease treatment. Herein, the green synthesis of silver nanomaterials using organic green sources has been evaluated and discussed. These kinds of materials are widely used for treatment of antibiotic-resistant bacteria, cancer and etc due to their elegant properties compared with other chemical ways and drugs. Moreover, the outcome of green-based approaches were compared with chemical procedures and obtained data were examined via various analyses including UV-visible spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), atomic force microscopy (AFM) and Fourier transforms infrared spectroscopy (FT-IR). In this study, variety of green methods were investigated to present a summary of recent achievements toward highlighting biocompatible nanoparticles, all of which can reduce the toxicity of nanoparticles, make them eco-friendly, reduce their side effects and decrease the production cost. The nature of these biological organisms also affect the structure, shape, size and morphology of synthesized nanoparticles.