**9. Future perspectives**

hypodermic needles [321]. Microneedles have been made from a variety of materials and in particular the polymers have been shown to be effective. They have also been produced in solid and as well as in hollow forms. Solid microneedles are used to render skin permeable, whereas hollow microneedles actively deliver drugs into the skin at a controlled rate. In contrast, jet injectors deliver a high-velocity liquid jet stream into the skin, delivering drugs into various skin layers, depending on the jet parameters [322]. Jet injectors have a long history, particularly in the delivery of vaccines, insulin, and growth hormone. Ultrasound enhances skin permeability by cavitation, which temporarily disrupts skin structure [323]. Iontophoresis and electroporation use electric fields to alter the skin structure and/or provide additional driving force for drug penetration through the skin [324]. These new routes of administration of therapeutics with improved responses have been achieved by high drug concentration in target, permeation, no first-pass effect, high bioavailability and compliance administration

The uses of bio-nanotechnology in therapeutics a number of unexpected inventions have been done recently on polymer based nanometers, which have great attention in the field of smart drug delivery applications. The biomaterials including protein based polymers, polysacchar‐ ide based polymers, natural or synthetic or semi-synthetic polymers, various biomaterials and combination of polymer have utilized to prepare various kinds of nano-formulations towards the smart drug delivery applications. Several polymeric nanoparticle-based therapeutic systems have been established for the treatment of various diseases. Several nanoparticle based drug delivery systems have been approved in clinical trials, some of them in under pre-clinical trial levels, this nanoparticle based system can provide the increased half-life, high biocom‐ patibility, and minimum immunogenicity, site targeting and overcome the membrane barriers. Also the last era, major and new identifications have been drastically established in the smart material that alter its own structure and function in response to the environment. This performance has been used for the fabrication smart drug delivery systems, Smart polymer matrices release drugs by environment responses this system have been successfully achieved. In parallel the new method of bottom-up and top-down nanofabrication technologies provided precisely controlled size and shaped nano-particulate delivery system. Simultaneously, various advanced significant routes of targeting have developed and successfully achieved to the site of action. At present, the field of microfluidics for synthesis, micro-needle for trans‐ dermal and site targeted delivery is still in its infancy. So the pharmaceutical industry has to bring these products into industry-led investigation and the improvement in this would

without enzymatic destruction [325, 326].

284 Application of Nanotechnology in Drug Delivery

possibly to quicken their progress.

**8. Conclusion**

Although there are considerable amount researches have been done in the field of drug delivery so far. In the polymeric nanoparticle based drug therapy has to be enhanced by incorporating by the combination therapies, Smart delivery has been achieved successful‐ ly in the case of cancer, but need to be concentrating more on other pathologies, also numerous challenges remain. From the material viewpoint, most of the smart delivery systems mechanism do well in vitro studies but flops the in vivo studies. So the research has to be re-considering to come up with simple, straightforward, efficient and reasona‐ bly accurate preparations with broadly applicable strategies, the pharmacologically active agent targeting to pathological sites, for the development of smart drug delivery systems. In technology vice the research has to focus into the fusion technologies. Although several specific specialized technologies have been shown to in polymer synthesis, functionaliza‐ tion, analysis, in vitro and in vivo study in the field of polymer science, the combinations of two or more techniques are often more effective than single technologies like a combina‐ tion of controlled radical polymerization with click chemistry. The fusion technologies can fulfil the various existing drawbacks of some individual technologies, and this has the high potentiality, synergistic enhancement in safest nanoparticle based drug delivery. Consider merging and adopting two or more right technologies for getting a high-throughput technology by selecting the right combinations is a fruitful area for research that is still largely unexplored. This new understanding must be incorporated into the future of newer polymeric based nanoparticle synthesis development and evaluation of smart drug delivery. Also the next generation of polymeric nanoparticle based delivery systems with drugs like growth factors, hormones, antibodies, genes, peptides, etc.; should also enhance the efficiency and minimize the unwanted effects.
