In late December 2025, a research group in China published a comprehensive review on an emerging material in the microneedle landscape: natural polysaccharides. While these “complex carbs” are derived from simple plant, animal, and microbial sources, their potential for 3D fabrication is anything but basic. Unlike traditional silicon or synthetic polymer microneedles that act as passive “envelopes,” polysaccharide microneedles (PMNs) function as active therapeutic platforms. Because they are inherently biocompatible, biodegradable, and capable of priming the immune system, they are being reimagined as a tool for cancer immunotherapy. The review, published in Glycoscience & Therapy, in part explored how micro molding and 3D printing are being used to fabricate such tools. After explaining why polysaccharides are a desirable material, we’ll get into how AM technologies specifically are unlocking their potential.
Why Polysaccharide Microneedles?
Natural polysaccharides offer a “living” alternative to the inert or brittle materials traditionally used in 3D printing. While inorganic substances like silicon and glass carry a high risk of fracturing and leaving hazardous shards in the skin, polysaccharides are bioresorbable, safely dissolving into harmless metabolites after delivery. More importantly for oncology, these complex carbohydrates are bioactive. They act as natural adjuvants that “prime” the immune system to recognize tumor cells more effectively.
3D Printing: Addressing Polysaccharides’ Rheology
For engineers, the challenge with natural polysaccharides is their rheology and mechanical properties. While they are biological powerhouses, they often lack the structural integrity required to penetrate the skin’s tough outer barrier without buckling. To bridge this gap, the research group identified three fabrication strategies that leverage 3D printing’s precision to reinforce these soft materials.
1. Indirect Fabrication
The most common hurdle is that many polysaccharides are too viscous or structurally “soft” for high-resolution direct printing via stereolithography (SLA). To solve this, researchers use indirect additive manufacturing. In this workflow, high-resolution digital light processing (DLP) or SLA is used to print a “master” microneedle array with sub-micron accuracy. This master serves as a template to create a negative silicone mold.
By shifting 3D printing to the molding stage, engineers can achieve complex biomimetic geometries. This could include features like octopus-inspired suction cups or barbed tips that maximize skin adhesion. The polysaccharide is then cast into these molds, inheriting a sophisticated architecture that would be impossible to achieve through traditional etching or milling.
2. Hybrid Structural Skeletons
When a mold isn’t sufficient, and the needle needs more backbone, researchers turn to a composite architecture. Rather than relying on the polysaccharide to provide both the drug payload and the mechanical structure, 3D printing is used to create a rigid internal skeleton.
In this method, a structural core is printed using a high-strength polymer. This skeleton is then dip-coated in a polysaccharide solution. A representative example involves the use of continuous liquid interface production (CLIP), a high-resolution 3D-printing technology that utilizes oxygen-permeable membranes and controlled photopolymerization to rapidly generate MNs with optimized surface topographies. Researchers have increased drug-loading capacity by over 30% with this strategy, compared to monolithic needles. This ensures the therapeutic layer is distributed uniformly across every needle.
3. Smart Hydrogel Reservoirs
In advanced cancer immunotherapy, a patch needs to be more than just a needle; it needs to act like a programmable pump. To achieve this, researchers are using FDM to print integrated “iontophoretic” systems, essentially devices that use a small electric current to push medication through the skin.
In this setup, the 3D printer builds the rigid structural housing, while the “engine” of the device is a polysaccharide hydrogel, such as agarose. This gel serves a dual purpose: it acts as a reservoir for the drug and an electrolyte that conducts the electric current. By combining this 3D-printed frame with ultrasound-activated transport, these hybrid systems can “drive” medication into the body with incredible precision, achieving up to 93% delivery efficiency for both small molecules and complex proteins.
The Future of Scalable Oncology
The integration of polysaccharide science and 3D printing marks a move away from “one-size-fits-all” drug delivery toward intelligent, personalized oncology. By utilizing 3D printing to overcome the structural limitations of natural sugars, researchers have created a platform that is like a high-precision transport vehicle. These intelligent patches offer a scalable, minimally invasive alternative to traditional immunotherapy, and we’ll have to watch to see how the technology develops. To learn more, find the full review HERE.
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*All Photo Credits: Zhang et al.