Determination of Microneedle Puncture Performance

Microneedling is an efficient, safe, and novel transdermal drug delivery technique that possesses advantages that cannot be achieved by other traditional transdermal drug delivery techniques. Microneedle materials can be metals, polymers, hydrogels, etc.; there are also many different types of microneedles, such as hollow microneedles, solid solid microneedles, soluble microneedles, and dissolving microneedles. Microneedles can rapidly open skin channels to deliver drugs into the skin with no or minimal damage to the dermis. CD Formulation offers skin puncture experiments based on expertise and experience, and provides evaluation of puncture performance.

Fig.1 Penetration performance of microneedle arrays. (Yong et al., 2022)

Microneedle Skin Penetration Experiment

Although measuring the fracture force and compression properties of microneedles can simulate the theoretical penetration process of microneedles without using isolated skin and predict the effectiveness of microneedle penetration, the actual penetration effect of microneedles cannot be accurately predicted by fracture force or compression properties due to the influence of the process of microneedle use on the penetration and the large difference between the skin and flat surfaces such as stainless steel plates. Therefore, most studies have used biological tissues (usually isolated human skin or animal skin) to examine the real penetration performance of microneedles. Microneedle skin puncture experiments, compared with real skin, are easy to standardize skin models, have high test efficiency and reproducibility, and are more ethical, and can be applied to pig skin penetration tests to evaluate microneedle penetration performance.

Puncture performance evaluation methods

The main methods for evaluating microneedle penetration performance are mechanical test, staining method, epidermal water loss method (TEWL), resistance method, OCT, electron computed tomography (CT), fluorescent staining and labeling method, tissue sectioning method, and paraffin membrane puncture method.

Microneedle puncture performance evaluation

• Penetration force

The minimum force required for a microneedle to pierce the skin is the penetration force. The determination of penetration force is influenced by many factors such as microneedle parameters, application force, measurement method, skin type, and environmental conditions. The force applied by the microneedle must be designed to be greater than the penetration force in order for the microneedle to effectively penetrate the skin, while controlling the intensity of the force to minimize the pain caused to the user.

• Penetration rate

The penetration rate is the ratio of the number of microneedles in the microneedle array that are sufficient to pierce the epidermis to the number of all microneedles in the array. A high penetration rate indicates that the microneedles can effectively break through the epidermal barrier for drug delivery.

• Depth of penetration

The penetration depth refers to the distance from the microneedle tip to the skin surface after the microneedle penetrates the skin. A good penetration depth should be able to break through the stratum corneum and effectively improve the drug delivery efficiency without touching the painful nerves.

Among them, CD Formulation's evaluation of the penetration force and penetration rate of microneedle puncture can be obtained directly by mass spectrometry and staining method, which is simple and fast. The observation of the penetration depth often requires the use of imaging instruments and methods such as OCT and histological sections. In addition, fluorescence spectroscopy, Raman spectroscopy, CLSM, can be used to evaluate the diffusion and distribution of microneedle-delivered bioactive molecules in simulated and real skin. If you want to perform microneedle puncture experiments and evaluate the performance of microneedle puncture, choose us and we will customize a solution for you.

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