Nanostructured Microneedles for Transdermal Drug Delivery
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Solution Overview
Problem
Current methods for targeted drug delivery face challenges in overcoming the body's structural and immune barriers, leading to low bioavailability of bioactive agents, particularly for high molecular weight agents, as they are often recognized as foreign substances and targeted by the immune system.
Innovation Solution
The use of nanostructured microneedles that penetrate the stratum corneum and feature a patterned surface to interact with biological tissues, increasing the permeability of the dermal barrier and avoiding immune recognition, allowing for direct delivery of bioactive agents to the cardiovascular system with high bioavailability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If transdermal delivery is used to avoid pain and provide sustained delivery, then delivery comfort and sustainability are improved, but the stratum corneum barrier function is encountered
Solution Approach 1:
The delivery system uses an array of discrete microneedles (e.g., 500-10,000 needles) distributed across the patch surface, with each needle independently penetrating individual corneocytes. This segmentation allows the barrier to be overcome through numerous small penetration points rather than requiring a single large breach, maintaining overall skin integrity while enabling agent delivery.
Solution Approach 2:
The microneedles are designed with spatially varying properties: sharper tips at the distal end for effective penetration, gradually thickening shafts for structural integrity, and differential material composition (e.g., hydrophobic outer layer, hydrophilic inner core) to match local requirements at different positions along the needle and across the patch surface.
2Reliability
If agents are delivered across the dermal barrier, then transdermal delivery is achieved, but immune response and foreign body response are triggered
Solution Approach 1:
The microneedles serve as a temporary intermediary that facilitates direct delivery of the bioactive agent from the patch reservoir to the dermal capillary network, bypassing the lymphatic system. This intermediary mechanism reduces immune recognition by minimizing the agent's exposure to immune surveillance pathways while maintaining effective delivery.
Solution Approach 2:
The delivery system extracts and utilizes the natural micro-channels and capillary networks already present in the dermal layer, avoiding the need to create new pathways that would trigger immune response. The microneedles align with and utilize existing vascular structures for agent transport.
3Reliability
If conventional delivery methods (oral or injection) are used, then agents can be delivered to the system, but gastrointestinal distress and pain occur
Solution Approach 1:
The system replaces the mechanical injection process (needles, syringes, muscle penetration) with a distributed microneedle array that uses controlled micromechanical penetration of the stratum corneum. This substitution eliminates the pain associated with deep tissue injection while maintaining effective agent delivery through the dermal barrier to systemic circulation.
4Speed
If bursts of agents are delivered rather than steady-state, then rapid effect is achieved, but pharmacokinetic control is reduced
Solution Approach 1:
The delivery system employs periodic release mechanisms where the microneedles deliver agents in controlled pulses or sustained low-level releases rather than a single large burst. This periodic action pattern allows for both rapid initial effect and extended duration of action, with the release rate adjustable based on the specific therapeutic requirements and agent characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves a bioavailability greater than 20% compared to subcutaneous delivery, effectively bypassing the lymph system and minimizing immune targeting, allowing for efficient and sustained delivery of high molecular weight agents like protein therapeutics.
Implementation Method 1
penetrating the stratum corneum of the subject with a microneedle
Implementation Method 2
increasing the permeability of the dermal barrier
Data Source
AI summary
A method for delivering a bioactive agent to the cardiovascular system is described. The method delivers the agent at a high bioavailability and with little loss of agent to the natural defense mechanisms of the body. For instance, little or none of the bioactive agent will be sequestered in lymph tissue and prevented from circulation in the cardiovascular system. The method includes utilization of a transdermal delivery device including microneedles with structures fabricated on a surface of the microneedles to form a nanotopography. A random or non-random pattern of structures may be fabricated such as a complex pattern including structures of differing sizes and/or shapes.