Nanoformulation Encapsulation Efficiency Testing Service

Encapsulation efficiency is an important indicator for evaluating the quality and process quality of dosage forms such as nanocapsules, microspheres, and liposomes. CD Formulation has developed appropriate encapsulation efficiency testing methods to meet customers’ different requirements for their samples to be tested, including size exclusion chromatography, microcolumn centrifugation, dialysis, etc.

Our Nanoformulation Encapsulation Efficiency Testing

After we obtain microcapsules, microspheres, and liposomes dispersed in a liquid medium during preparation, we separate them by appropriate methods (such as gel column chromatography, centrifugation, or dialysis) and measure their encapsulation efficiency. The specific experimental process is as follows. First, use a certain method to separate unencapsulated free drugs from microcapsules, microspheres, or liposomes and measure their drug content. Then calculate the encapsulation rate based on the total dosage. After separation, we will measure the ratio of the amount of encapsulated drug (liposome) to the phospholipid and calculate the drug-lipid ratio.

Fig.1 Our workflow of encapsulation efficiency testing for nanoformulations. (CD Formulation)

Our Techniques for Nanoformulation Encapsulation Efficiency Testing

Size Exclusion Chromatography (gel chromatography)

This method uses the difference in molecular weight and particle size between liposomes and free drugs to separate. The liposomes with larger particle sizes are eluted first, and the free drugs with smaller particle sizes are eluted later to achieve the separation effect.

Microcolumn Centrifugation

The microcolumn centrifugation method can quickly and easily separate liposome internal and external phase drugs, requires a small sample amount, and hardly affects the liposome encapsulation efficiency determination of the original sample properties and status. It is especially suitable for the detection of some intermediate processes, such as drug release processes and active drug loading processes.

Dialysis

This method is to put the drug into a dialysis bag with a certain molecular weight cutoff, and then place the dialysis bag in a dialysis medium that is many times larger than its volume. The free drug permeates from the inside of the dialysis bag to out of the dialysis bag along the concentration gradient. Liposomes cannot penetrate the external medium due to their large particle size. Then the drug concentration in the medium is measured at different times until the drug concentration in the external medium remains unchanged, indicating that the concentration of free drugs inside and outside the dialysis bag is the same and reaches balance. The time at this time is used as the dialysis equilibrium time of the free drug. The drug concentration in the medium at this time is measured to calculate the concentration of the free drug, and then the encapsulation efficiency is calculated.

Centrifugation

The centrifugal method is used to determine the encapsulation efficiency based on the different centrifugal forces experienced by liposomes and free drugs due to different specific gravity, resulting in different sedimentation speeds to achieve separation.

Ion Exchange Chromatography

Ion exchange chromatography separates free drugs and liposomes based on the differences in charges.

NMR Method

In this approach, a pH-sensitive proton chemical shift reagent is employed as a tracer when there is a transmembrane pH gradient. The resonance signal shift of the free drug and the encapsulated drug is observed at various pH levels by modifying the pH of the external medium surrounding the liposome. This allows for the differentiation between encapsulated and unencapsulated drug peaks within the liposome, enabling the determination of the liposome's encapsulation efficiency.

Fluorescence Quenching Reaction

The fluorescence quenching reaction method uses a fluorescence detector to measure the fluorescence value and accurately determines the concentration of the fluorescent substance initially encapsulated and unencapsulated by liposomes to calculate the encapsulation efficiency.

Electron Spin Resonance Spectroscopy

We developed electron spin resonance spectroscopy for the determination of encapsulation efficiency, and the electron spin band of the external label is significantly broadened when a paramagnetic reagent such as iron hydride is added. We can also use the difference in diffusion coefficient between the label encapsulated inside the liposome and the free label to determine the encapsulation efficiency.

Protamine Agglutination Method

In this method, we first quickly mix a certain number of liposomes and protamine solution, the liposomes and protamine aggregate, and the supernatant (or filtrate) and the agglomerate are separated by filtration or centrifugation. The drug concentration in the supernatant (or filtrate) is then measured as the concentration of the free drug, and the drug concentration in the aggregate is the concentration of the drug encapsulated in the liposomes, and finally, the encapsulation rate is calculated.

Why Choose Us to Test Nanoformulation Encapsulation Efficiency?

• We have a variety of world-class equipment for encapsulation efficiency testing, such as chromatography, NMR, fluorescence spectrophotometer, etc.
• Our technical team has rich experience in the characterization services of nanomedicines, especially encapsulation efficiency testing during both nanoformulation development and quality control.
• We have complete analysis and testing service management specifications, and a relatively fast sample circulation cycle, and can provide you with our professional proposal and test report immediately.
• We also provide customers with thoughtful after-sales technical consulting services for free. If you have any questions within 15 working days of receiving the test report, our team will answer your questions as quickly as possible.

Published Data

CD Formulation can quickly respond to your requirements for encapsulation efficiency testing and provide you with our professional analytical services for your nanoformulation development needs. If you have any questions about encapsulation efficiency testing, please feel free to contact us for detailed communication.

How It Works

STEP 1

Submit a service request describing your specific research or development need.

STEP 2

We'll email you to provide your quote and confirm order details if applicable.

STEP 3

Execute the project with real-time communication, and deliver the final report promptly.