Comparison of polymers to enhance mechanical properties of microneedles for bio-medical applications

Abstract

To pierce through the skin and interact with the first biofluid available, microneedles should be mechanically strong. However, some polymers used to fabricate microneedles yield insufficient strength for the fabrication of arrays (PDMS, highly porous structures, etc.). To enhance mechanical properties, piercing materials can be used. They aim to pierce the skin evenly and dissolve quickly, clearing the way for underlying microneedles to interact with the interstitial fluid (ISF). Three materials-carboxymethyl cellulose (CMC), alginate, and hyaluronic acid (HA)-are discussed in this article. Low concentrations, for a quick dissolution while keeping enhancing effect, are used ranging from 1-5%(w/w) in deionized water. Their overall aspects, such as geometrical parameters (tip width, height, and width), piercing capabilities, and dissolution time, are measured and discussed. For breaking the skin barrier, two key parameters-a sharp tip and overall mechanical strength-are highlighted. Each material fails the piercing test at a concentration of 1%(w/w). Concentrations of 3%(w/w) and of 5%(w/w) are giving strong arrays able to pierce the skin. For the purpose of this study, HA at a concentration of 3%(w/w) results in arrays composed of microneedles with a tip width of 48 ± 8 μm and pierced through the foil with a dissolution time of less than 2 min.

Engineering Microneedle Patches for Improved Penetration: Analysis, Skin Models and Factors Affecting Needle Insertion

“…If some polymers have insufficient piercing abilities, piercing materials can be used in conjunction with the MNs themselves. For example, one study used hyaluronic acid, carboxymethyl cellulose and alginate as a piercing material to pierce the skin quickly (through quick dissolution) and evenly, thereby allowing underlying MNs to interact with interstitial fluid [ 181 ]. This study found that a sharp needle tip and overall mechanical strength were the two most important factors affecting needle insertion.…”

Antibiofilm Efficacy of the Pseudomonas aeruginosa Pbunavirus vB_PaeM-SMS29 Loaded onto Dissolving Polyvinyl Alcohol Microneedles

“…The height and base diameters were reduced by approximately 5.08% and 7.32% in the INL MNs compared to the silicon MNs ( Figure 2 ) and 14.19% and 1.74% for BA MNs compared to the purchased molds’ specifications. Differences in height and base diameters between master molds and polymer MNs are common due to the dehydration of the polymer and have been reported for different dissolvable, swellable and biodegradable polymers [ 50 , 51 ]. For instance, Demir et al used pyramidal-shaped MN (900 µm height and 250 µm base diameter) and six polymers to produce MNs.…”

Microneedle-Based Natural Polysaccharide for Drug Delivery Systems (DDS): Progress and Challenges

“…GwenaëlBonfante et al discussed three materials-carboxymethyl cellulose (CMC), alginate, and hyaluronic acid (HA)-for the manufacture of microneedles. However, the microneedles have been designed with low concentrations for rapid dissolution while maintaining the strengthening effect and were used varying from 1 to 5% (w/w) in deionized water [138]. Their overall performance aspects, such as geometric parameters (width, height, and tip width), piercing capabilities, and dissolution time, are measured and discussed.…”