Powerful Tools for Precise Engineering of Viatel Diblock Nanoparticle Size: Polymer and Solvent Structure

This poster was presented at CRS 2024 in Bologna

Purpose

Nanomedicine has immense potential as it offers nanoparticle(NP)-based delivery vehicles for vaccines or APIs. Polymeric NPs have been used for drug delivery due to their biocompatibility, biodegradability and potential to provide customized properties by tailoring polymer chemistry. NP size is a critical factor that impacts circulation time, in vivo biodistribution and cell uptake[1-3]. Also, NPs < 200 nm can be sterile filtered. Thus, it is crucial to control NP size. Herein, we determined the most effective factors to control NP size[4].

Method

Polymeric NPs were made by nanoprecipitation (illustrated in figure 1). Two compositions of an amphiphilic bioresorbable diblock copolymer marketed by Ashland Inc., Viatel DL 03 PEG5K, methoxy poly(ethylene glycol)-b poly(D,L-lactide) were used. Each had a PEG length of 5 kDa but varying PLA:PEG ratio (60:40, 75:25 wt%).

(click the graphics to enlarge them)

figure 1. nanoparticle formation method, nanoprecipitation — Figure 1. nanoparticle formation method, nanoprecipitation

Table 1 provides nanoprecipitation conditions in detail. dynamic light scattering (DLS) method was used to measure NP size. NPs were imaged by transmission electron microscope (TEM). API loaded NPs were lyophilized, dissolved in ACN and assayed with HPLC to determine API loading.

table 1. nanoprecipitation parameters — Table 1. nanoprecipitation parameters

Results

Figure 2 shows the size distribution results for both polymers using 100% acetone as solvent. TEM images in figure 3 showed spherical monodisperse morphology for these NPs.

figure 2. size distribution of polymeric NPs. — Figure 2. size distribution of polymeric NPs.

figure 3. TEM images of lyophilized Viatel TM NP using 5% CavitronTM W7HP5 as lyoprotectant — Figure 3. TEM images of lyophilized Viatel TM NP using 5% CavitronTM W7HP5 as lyoprotectant

ACN exhibits similar behavior as acetone (Fig 4.A). Increasing NMP content led to formation of larger NPs when using PLA-PEG(75:25) (Fig 2.B). The strongest effect was observed for DMSO(Fig 4.C). It increases NP size to 192.95 nm with PLA-PEG(75:25). Fig 4. D compares the effect of all solvents on NP size.

table 2. API loaded NP characterization — Table 2. API loaded NP characterization

Table 2 summarizes characterization data for API loaded ViatelTM PDLLA:PEG (75:25). Target API loading for these NPs was 10%. Figure 5 shows in vitro release profile of the model API (Atorvastatin from NPs over 48 hours).

figure 4. effect of solvent structure/composition on NP size — Figure 4. effect of solvent structure/composition on NP size

Conclusion

PLA-PEG NP size can be adjusted with two main parameters: polymer structure and solvent choice. Increasing the hydrophobic fraction of the polymer results in formation of larger NPs. Introducing DMSO and NMP into the polymer solution has a significant effect on NP size. As the content of the second solvent increases NP size increases too. Combination of these two parameters allows to precisely design and produce NP with a wide range of diameters.

See the poster “Powerful Tools for Precise Engineering of Viatel Diblock Nanoparticle Size” here

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Source: Niloofar Heshmati, Hamza Chouirfa, Michael Kogan, Kamaru Lawal, Shuyu Xu, Sangrama Sahu, Fengyuan Yang, Patrick Duffy, Cory Mahnen, Thomas Durig, Powerful Tools for Precise Engineering of Viatel Diblock Nanoparticle Size: Polymer and Solvent Structure, Ashland, CRS 2024 Poster “Powerful Tools for Precise Engineering of Viatel Diblock Nanoparticle Size”

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