The Erlich's "Silver Bullet" is the final goal for any drug delivery researcher to accomplish. The development of various engineered nanocarrier systems for the delivery of drugs to the specific diseased locations in the body possess fresh challenges every time. The stability of the nanocarrier is very important inside the body. The carrier when injected into the blood stream it should not be degraded or dissolved immediately. At the same time it should not elicit any immune response. Most importantly, the carrier should not leak the drug until it reach the target site. To attain these basic but important things, researchers mostly chose the systems that have the stable charge distributed all over the carrier system. Research showed that the positive charged systems elicit immune response at a faster rate compared to negative and neural charged carriers.
While designing a carrier for a particular drug the architecture of the carrier are very important. The shape and nature of the carrier plays an important role. Spherical carrier of different chemical nature like polymers, liposomes, nanoparticles are widely exploited. The polymer drug carriers are mainly used in the cases where the drug has to be released for a long time. For the case of liposomes, it is burst release or quick release and their life time at the targeted site is less. These carrier choices, to achieve specific duties, helps in enhancing the effectiveness of the carrier and also decrease the number of drug dosage times for the patient.
Though these carriers seems to be promising, still there is room to increase their efficiency of drug loading and drug targeting particularly DNA or si-RNA targeting. The polymers such as Poly-L-Lysine, Polyethyleneimine etc are widely used to deliver these genetic material. These polymers are positive charged polymers that form tight complexes with the negatively charged DNA or si-RNA. A more protection is needed for this genetic material from the surrounding molecules and enzymes that degrade these once injected into the blood stream. A new approach of designing the delivery carriers to overcome these problems is reported recently. The layer-by-layer approach for the delivery of genetic material is reported by Deng et al., published in ACS Nano.
The cartoon showing the Layer-by-Layer designed drug delivery carrier system
Such engineered carrier systems are the future for a sustained, stable and effective delivery of the load to the targeted site.
Zhou J. Deng, Stephen W. Morton, Elana Ben-Akiva, Erik C. Dreaden, Kevin E. Shopsowitz, Paula T. Hammond†, Layer-by-Layer Nanoparticles for Systemic Codelivery of an Anticancer Drug and siRNA for Potential Triple-Negative Breast Cancer Treatment. ACS Nano 7 (2013) 9571-9584.