**9. Morphology and surface patterning of nanoparticles**

Scientists already developed different advanced techniques to examine the meso-, nano-, and micro-, and macroscale porosity within the polymer nanoparticles, and this porous surface patterning depends on the self-assembly of chosen materials. Polymer nanoparticles' preparation is fairly easy, and they show good control over the size and shape with longer clearance time. The extensive use of polymer nanoparticles has led to study the surface properties based on its pharmaceutical and industrial applications [57–61]. For example, PVA and PLA nanoparticles show unique characteristic properties to modify their surface with greater control of size. However, double emulsion techniques can be applied to stabilize the PVA nanoparticles. The protein containing nanoparticles has limitations on the increase of nanoparticle size upon functionalization with other nanomaterials. The protein bovine serum albumin (BSA) containing PLGA nanoparticles has good control on its size and shape while functionalizing through the solid-in-oil and oil-in-oil microsphere development method with suspended droplet hardening using impeller atomization followed by the droplet shearing in a spinning oil film approach. As shown in **Figures 7** and **8**, the gold nanoparticles have good interactions with polymer micelles and formed a new nanomaterial which is

the combination of polymer micelle and gold nanoparticles with functionalized features. Similarly, iron and iron oxide containing a core of magnetite had a primary coat of a polymer of dextrans to get microspheres for bio applications [62].

However, liposomes have a spherical vesicular structure formed by the combination of hydrophilic head part and hydrophobic tail or hydrocarbon (fatty acid) chain which are called phospholipid bilayers. The hydrophilic and hydrophobic parts of the phospholipids are the main cause to form the liposome and for its structural integrity. The images in **Figure 7** corroborate the monodispersed silica (SiO2) nanoparticles prepared by using modified Stober's sol–gel method. The formation of spherical-shaped SiO2 nanoparticles depends on the stirring methods, the solvent used for the preparation, rotations per minute (RPM), purity of chemicals used for the synthesis of SiO2 nanoparticles, surfactants, and equipment used for the experiments [66]. **Figure 7** shows sharp uniform-sized monodispersed silica nanoparticles are penetrating the boundary of polymer thin film and sitting inside the film. Scientifically, it's a composite of polymer-silica, but specifically, here, in this case, polymer thin film has been inserted with the mesoporous silica nanoparticles. Nucleic acids are another class of biopolymers which are called as polysaccharides, and they can also be involved in the development of nanocarrier capsules or particles for biomedical applications. The chemical linkage between nucleic acid monomers is phosphodiester, and it also helps in the development of nanoparticles through the self-assembly manner. The synthesized PP-based nanoparticles have precise control

#### **Figure 7.**

*Transmission electron microscopic images. (a, b) Silica nanoparticle internalization into polymer thin film, (c) bare silica nanoparticles and separate polymer thin film interactions, (d) pure silica nanoparticles showing mesoscale porosity at the center and uniform size of particles at higher magnifications [62, 63].*

**153**

**Figure 8.**

*Polymer Properties: Functionalization and Surface Modified Nanoparticles*

over size and shape, and it can be controlled through the crystal sequestering of atoms and molecules [67]. Distribution of the guest particles and molecules inside the host matrix can be optimized through the agitation methods like sonication time, temperature, stirring (RPM), incubation time, and encapsulation and entrapment. However, numerous possible applications in the biomedical field arise due to the presence of long-range order in the spatial distribution of nanocarriers. Block copolymers show unique and novel characteristic features to the pattern surface of capsules and nanoparticles with porosity. The self-assembly nature between functional groups of polymers is highly dependent on solvent interactions (**Figure 8**). Surface and morphology of particles can be tuned based on using selective solvents. Surface patterning is an ideal as lithography templates to the spontaneous selfassembly in nanometer (nm) to micrometer (μm) size topography. The surface patterned by self-assembly of block copolymers thereby reduces the number of process

*Transmission electron microscopic images. (a, b) Gold nanoparticles functionalized with polymer micelle, image (c) dense polymer micelle, (d) gold nanoparticles arranged in a core-shell morphology with the eternal polymer micelles, (e) bare gold nanoparticles, and (f) shows lattice parameters of AuNPs [64, 65].*

Sometimes pore size and shape throughout the surface of the capsules and nanoparticles may appear irregular and inconsistent because of interatomic and molecular orientations and imprinting methods. However, intermolecular attractions also show the effect on the morphology of particles. There are highly inconsistent pores with smooth and rough surfaces because of the solvent effect and sonication methods. From **Figure 9**, AFM images of the surface profile for zinc oxide nanoparticles have been measured, and it shows the surface characters. From the image (a), the arrangement of ZnONPs can be seen, and the line scan profile gives a channel type of surface morphology for zinc oxide nanoparticles, whereas wet chemical methods and sample preparation procedures also play a vital role to exhibit a considerable change in shape and surface morphology of polymer NPs. A non-contact mode AFM operation has been carried out to acquire the topography of the ZnONPs. However, tip size and magnification play a crucial role to acquire the topography of the NPs. Furthermore, for the uniform pores and consistent particle size, the shape can be optimized based on several factors such as sonication,

steps involved in the formation of such desired structures [68].

*DOI: http://dx.doi.org/10.5772/intechopen.84424*

*Polymer Properties: Functionalization and Surface Modified Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.84424*

#### **Figure 8.**

*Role of Novel Drug Delivery Vehicles in Nanobiomedicine*

the combination of polymer micelle and gold nanoparticles with functionalized features. Similarly, iron and iron oxide containing a core of magnetite had a primary

*Transmission electron microscopic images. (a, b) Silica nanoparticle internalization into polymer thin film, (c) bare silica nanoparticles and separate polymer thin film interactions, (d) pure silica nanoparticles showing* 

*mesoscale porosity at the center and uniform size of particles at higher magnifications [62, 63].*

However, liposomes have a spherical vesicular structure formed by the combination of hydrophilic head part and hydrophobic tail or hydrocarbon (fatty acid) chain which are called phospholipid bilayers. The hydrophilic and hydrophobic parts of the phospholipids are the main cause to form the liposome and for its structural integrity. The images in **Figure 7** corroborate the monodispersed silica (SiO2) nanoparticles prepared by using modified Stober's sol–gel method. The formation of spherical-shaped SiO2 nanoparticles depends on the stirring methods, the solvent used for the preparation, rotations per minute (RPM), purity of chemicals used for the synthesis of SiO2 nanoparticles, surfactants, and equipment used for the experiments [66]. **Figure 7** shows sharp uniform-sized monodispersed silica nanoparticles are penetrating the boundary of polymer thin film and sitting inside the film. Scientifically, it's a composite of polymer-silica, but specifically, here, in this case, polymer thin film has been inserted with the mesoporous silica nanoparticles. Nucleic acids are another class of biopolymers which are called as polysaccharides, and they can also be involved in the development of nanocarrier capsules or particles for biomedical applications. The chemical linkage between nucleic acid monomers is phosphodiester, and it also helps in the development of nanoparticles through the self-assembly manner. The synthesized PP-based nanoparticles have precise control

coat of a polymer of dextrans to get microspheres for bio applications [62].

**152**

**Figure 7.**

*Transmission electron microscopic images. (a, b) Gold nanoparticles functionalized with polymer micelle, image (c) dense polymer micelle, (d) gold nanoparticles arranged in a core-shell morphology with the eternal polymer micelles, (e) bare gold nanoparticles, and (f) shows lattice parameters of AuNPs [64, 65].*

over size and shape, and it can be controlled through the crystal sequestering of atoms and molecules [67]. Distribution of the guest particles and molecules inside the host matrix can be optimized through the agitation methods like sonication time, temperature, stirring (RPM), incubation time, and encapsulation and entrapment. However, numerous possible applications in the biomedical field arise due to the presence of long-range order in the spatial distribution of nanocarriers. Block copolymers show unique and novel characteristic features to the pattern surface of capsules and nanoparticles with porosity. The self-assembly nature between functional groups of polymers is highly dependent on solvent interactions (**Figure 8**). Surface and morphology of particles can be tuned based on using selective solvents. Surface patterning is an ideal as lithography templates to the spontaneous selfassembly in nanometer (nm) to micrometer (μm) size topography. The surface patterned by self-assembly of block copolymers thereby reduces the number of process steps involved in the formation of such desired structures [68].

Sometimes pore size and shape throughout the surface of the capsules and nanoparticles may appear irregular and inconsistent because of interatomic and molecular orientations and imprinting methods. However, intermolecular attractions also show the effect on the morphology of particles. There are highly inconsistent pores with smooth and rough surfaces because of the solvent effect and sonication methods. From **Figure 9**, AFM images of the surface profile for zinc oxide nanoparticles have been measured, and it shows the surface characters. From the image (a), the arrangement of ZnONPs can be seen, and the line scan profile gives a channel type of surface morphology for zinc oxide nanoparticles, whereas wet chemical methods and sample preparation procedures also play a vital role to exhibit a considerable change in shape and surface morphology of polymer NPs. A non-contact mode AFM operation has been carried out to acquire the topography of the ZnONPs. However, tip size and magnification play a crucial role to acquire the topography of the NPs. Furthermore, for the uniform pores and consistent particle size, the shape can be optimized based on several factors such as sonication,

#### **Figure 9.**

*Atomic force microscopic images acquired for the ZnO nanoparticles. The image (a) corresponds to phase(s), and it shows the surface properties of ZnO NPs, image (b) elucidates the three-dimensional view of ZnONPs and their morphology, the image (c) illustrates the surface properties of ZnONPs arranged on the substrate, and these are acquired from the line scanning mode AFM operation as represented in the image (a) phase [64, 65, 69, 70].*

#### **Figure 10.**

*Schematic shows the factors which cause the surface modification and functionalization in polymer nanoparticles.*

solvent, pH, and concentration of the system (**Figure 10**). The nanoscale clustering and complexation of the peripheral of nanoparticles and capsules have been done through the modification of active functional groups as potential substrates for subsequent functionalization and surface modifications. The post-insertion method is used for the preparation of dendrimer nanoparticles and lipid nanocapsules (LNCs) with the chemically reactive surface. Ideally, this method has been designed for the grafting of ligands to the polymer compounds, and later it has been

**155**

**10. Conclusions**

*Polymer Properties: Functionalization and Surface Modified Nanoparticles*

extended to another particle development also. During the preparation of polymer nanoparticles or dendrimers, one can be focused on the experimental conditions such as the ratio between both reactants, quantity of solvent, external stimuli factors such as stirring methods, sonication, magnetic field, electric field applications,

The reaction conditions such as slow, fast, and moderate reactions can be tuned or controlled based on literature. The polymers, i.e., PCL, PLGA, PNIPAM, PS, and PEG, are advantageous to design the nanocapsules because they have the capability to form network structure which helps to load the drug molecules efficiently, and these properties help to sustain release of the medicines. The rigid morphology and close compacted structure of nanoparticles or nanocapsules with covalent bonding cannot allow us to modify its surface even at rigorous conditions also [71]. The loosely bound functional groups allow modifying the surface of the nanoparticles based on our applications. The homogeneous mixture of ingredients present in the polymer nanoparticles leads to form a close-compacted and smooth surface of the particles. However, development of a vinyl ether-functionalized poly phosphoester as a template for multiple post-polymerization conjugation core-shell type degradable polymeric nanoparticles was appended in the various publications, and those help to design and develop polymer NPs with surface-modifiable properties [72]. The confirmation and confinement of two reactants followed by the formation nanoparticles at the interface have a unique advantage to tune their surface properties based on its phase transitions and thermal stability, and this can help to improve and to know the reaction kinetics, higher yields, and selectivity of NPs. However, the presence of a liquid interface can accelerate the reaction through the phase-transfer catalyst which is employed to draw the reaction for the development of NPs based on phase transfer phenomena. Interestingly, the use of immiscible systems in emulsions offers an easy phase separation and formulation of desired nanoparticles. However, a brief overview on low molecular weight and low-density polymer complexes show the significant proximity of the interface in emulsions, and this strategy can be used for the efficient production of nano- and microparticles for various applications [65, 69–72]. However, several mechanisms were proposed for the formation of nanoscale pores within the nanoparticles because of the removal of some of the BCP fragments from the network of the PCL. The size of the BCP-based polymer nanoparticles reduced as blocks were removed from the parent blocks. As PCL is hydrophobic in nature, therefore BCP spheroids may be dissolved out from the PCL network structure and create the pores of the equivalent size of BCP spheroids. Moreover, as per factors appended in **Figure 10**, temperature change affects a lot on the pore size and morphology of nanoparticles [65, 73–78].

Herein, polymer synthesis, design, and development of nanoparticles and their functionalization have been discussed in detail. The various polymerization methods and different types of nanoparticles and capsules were reported in this chapter. The nanoparticle/capsule classification and surface functionalization followed by size, shape, and morphological changes based on industrial and biomedical applications have been corroborated. The polymer properties play a key role in the development of NPs with desired features, and such influencing factors were reported and elaborated in the respective sections. Nanoparticles and capsules with significant changeable surface and with a more specific surface area have potential applications in various fields. The porosity on the surface of nanoparticles and capsules is an important concern to prepare the NPs for both industrial and pharmaceutical applications.

pH, temperature, viscosity, density, and molecular weight of reactants [69].

*DOI: http://dx.doi.org/10.5772/intechopen.84424*

#### *Polymer Properties: Functionalization and Surface Modified Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.84424*

*Role of Novel Drug Delivery Vehicles in Nanobiomedicine*

**154**

**Figure 10.**

**Figure 9.**

*phase [64, 65, 69, 70].*

*nanoparticles.*

solvent, pH, and concentration of the system (**Figure 10**). The nanoscale clustering and complexation of the peripheral of nanoparticles and capsules have been done through the modification of active functional groups as potential substrates for subsequent functionalization and surface modifications. The post-insertion method is used for the preparation of dendrimer nanoparticles and lipid nanocapsules (LNCs) with the chemically reactive surface. Ideally, this method has been designed for the grafting of ligands to the polymer compounds, and later it has been

*Atomic force microscopic images acquired for the ZnO nanoparticles. The image (a) corresponds to phase(s), and it shows the surface properties of ZnO NPs, image (b) elucidates the three-dimensional view of ZnONPs and their morphology, the image (c) illustrates the surface properties of ZnONPs arranged on the substrate, and these are acquired from the line scanning mode AFM operation as represented in the image (a)* 

*Schematic shows the factors which cause the surface modification and functionalization in polymer* 

extended to another particle development also. During the preparation of polymer nanoparticles or dendrimers, one can be focused on the experimental conditions such as the ratio between both reactants, quantity of solvent, external stimuli factors such as stirring methods, sonication, magnetic field, electric field applications, pH, temperature, viscosity, density, and molecular weight of reactants [69].

The reaction conditions such as slow, fast, and moderate reactions can be tuned or controlled based on literature. The polymers, i.e., PCL, PLGA, PNIPAM, PS, and PEG, are advantageous to design the nanocapsules because they have the capability to form network structure which helps to load the drug molecules efficiently, and these properties help to sustain release of the medicines. The rigid morphology and close compacted structure of nanoparticles or nanocapsules with covalent bonding cannot allow us to modify its surface even at rigorous conditions also [71]. The loosely bound functional groups allow modifying the surface of the nanoparticles based on our applications. The homogeneous mixture of ingredients present in the polymer nanoparticles leads to form a close-compacted and smooth surface of the particles.

However, development of a vinyl ether-functionalized poly phosphoester as a template for multiple post-polymerization conjugation core-shell type degradable polymeric nanoparticles was appended in the various publications, and those help to design and develop polymer NPs with surface-modifiable properties [72]. The confirmation and confinement of two reactants followed by the formation nanoparticles at the interface have a unique advantage to tune their surface properties based on its phase transitions and thermal stability, and this can help to improve and to know the reaction kinetics, higher yields, and selectivity of NPs. However, the presence of a liquid interface can accelerate the reaction through the phase-transfer catalyst which is employed to draw the reaction for the development of NPs based on phase transfer phenomena. Interestingly, the use of immiscible systems in emulsions offers an easy phase separation and formulation of desired nanoparticles. However, a brief overview on low molecular weight and low-density polymer complexes show the significant proximity of the interface in emulsions, and this strategy can be used for the efficient production of nano- and microparticles for various applications [65, 69–72]. However, several mechanisms were proposed for the formation of nanoscale pores within the nanoparticles because of the removal of some of the BCP fragments from the network of the PCL. The size of the BCP-based polymer nanoparticles reduced as blocks were removed from the parent blocks. As PCL is hydrophobic in nature, therefore BCP spheroids may be dissolved out from the PCL network structure and create the pores of the equivalent size of BCP spheroids. Moreover, as per factors appended in **Figure 10**, temperature change affects a lot on the pore size and morphology of nanoparticles [65, 73–78].
