**3. Synthesis of microfluidic nanocarriers**

Beyond that, it seems that pharmaceutical formulators have been more interested in using synthetic nanocarriers than natural nanocarriers and colloidal systems, which have not been of much interest. Scientists have recently paid a lot of attention to the production of organic nano-carriers, particularly in pharmaceuticals, as pharmaceutical scientists have begun to recognize the important properties they confer on nano-carriers by microfluidic methods [21, 54]. Nano-carriers are created by spreading premade polymers or inducing polymers to develop through monomer reactions. These nanocarriers can be advanced in a variety of ways, and they are divided into classes based on the processes involved. In the primary group, materials are emulsified, but not necessarily in the other categories. As a result, it gives a straightforward and straightforward synthesis process. When those tactics are applied in typical devices, there is a lack of control over uniform blending, formation, and better impacts on formulation ingredients, and few goods have an excessive particle size dispersion as a result. Microfluidic control structures, on the other hand, can provide control over the aforementioned elements due to their equally sized particles [55]. Lipid polymer hybrid nanoparticles have been merged into high-capacity nanocarriers.

The microfluidic co-flow nanoprecipitation technology has been used to make a large number of LPHNPs. With the help of dissolving poly (lactic-co-glycolic acid) (2 mg/ml) into acetonitrile as a natural phase, the internal fluid changed its ordered state. The outer fluid had a two-to-three mass ratio of lecithin and Distearoylsn-glycero-3-phosphoethanolamine-polyethylene glycol 2000 dissolved in 4 percent ethanol and responded in water. These characteristics define a drug's potential to be a good choice for treating breast cancer [21, 22, 55].

Water-to-oil emulsification in a paper-based microfluidic drug carrier results in unique open-channel microfluidics with the capacity to manage the flotation of both adequate and inadequate surface tension liquids. The open channel devices are shown to be effective in limiting a variety of lower surface tension oils at high and low flow rates, allowing for microfluidic emulsification of water in oil in an open channel instrument. The droplets should be formed inside the channel with the aid of an adjustable speed of the continuous phases of the emulsified water and oil. Finally, an instrument has been turned to being used efficiently to synthesize remarkably monodisperse hydrogel microparticles that might contain a drug molecule.

Additional research into the drug delivery properties of manufactured products has yielded promising results. Open channel microfluidic devices have the potential to achieve a high level of fluid manipulation with fast and low-cost production [56]. Dopamine is used as a model drug to quantify electrochemical flow on paper-based devices in a dynamic microfluidic method. Combining electrochemical methods with microfluidic devices to achieve time-resolved detection of neuron-like PC12 cells cultured on filter paper Dopamine [57, 58]. After investigating the attachment of cells to the outside of the paper with a fluorescence microscope; dopamine drug delivery after stimulation with acetylcholine was investigated. As a result, the data collected by the device is consistent with single-cell statistics, demonstrating the effectiveness of the technique for high-throughput quantification of tissues or chemical targets on tissues [59] for higher-throughput quantification of chemical targets on tissues or organs-on-a-chip [58].

In general, microfluidic devices maintain many qualities in pharmaceutical science, consisting of appropriate doses, ideal drug delivery, site-targeted delivery, sustained release and controlled release, reduced repeated doses, and minimal side effects. To do so, these advantages are the key quality of the drug delivery system. Microfluidic technology has been routinely used in many active moiety carriers, direct drug delivery systems, high-throughput screening, and the production of polymers as superior carriers for additives and drugs. Cheaper and easily produced paper-based materials are good substrates that do solve several problems associated with transportation, filtration and storage, concentrators, valves, and multiplexing [59]. Going forward, creating microfluids on paper in controlled drug delivery programs can offer exciting opportunities to broaden the scope of the subject matter and support improved the scientific translation of drug delivery systems. A device for the controlled release of vinblastine (VBL) drug responsive to stimuli from magnetosensitive chitosan capsules, which is a magnetically sensitive device for controlled drug delivery, was developed by embedding superparamagnetic iron oxide (SPIO) nanoparticles (NPs) into a chitosan matrix and external magnet. Thus, the release rate, time, and dose of VBL released have become controlled by an exterior magnet. The prepared VBL and SPIO NPs-loaded chitosan microparticles were characterized and showed individual and distinctive controlled release patterns. In addition, droplet microfluidics, which is a unique technique for producing polymer spheres, has grown to be used for the manufacturing of monodispersed chitosan microparticles [60]. Because of their distinct physicochemical behavior and synergistic effects in the prevention and inhibition of colorectal cancer progression, atorvastatin and celecoxib were chosen as the version dosage form. For precisely controlled multidrug delivery, a microfluidic collection of monodisperse multistage pH-responsive polymer/porous silicone composites were developed [61]. Fabrication incorporating hypromerose succinate acetate, which does not dissolve in acidic conditions but incredibly dissolves in basic (alkaline) pH environments, is effective in preventing and suppressing the acceleration of colon and rectal cancers. Microcomposite [62] of Atorvastatin, which benefits from the larger pore volume of porous silicon (PSi), is first loaded into the PSi matrix and then encapsulated via microfluidics into pHresponsive polymer microparticles containing celecoxib, a multidrug obtained Road
