A Microneedle Technology for Sampling and Sensing Bacteria in the Food Supply Chain

Abstract

Food quality monitoring, particularly, the detection of bacterial pathogens and spoilage throughout the food supply chain, is critical to ensure global food safety and minimize food loss. Incorporating sensors into packaging is promising, but it is challenging to achieve the required sampling volume while using food‐safe sensor materials. Here, by leveraging water‐based processing of silk fibroin, a platform for the detection of pathogenic bacteria in food is realized using a porous silk microneedle array; the microneedle array samples fluid from the interior of the food by capillary action, presenting the fluid to polydiacetylene‐based bioinks printed on the backside of the array. Through the colorimetric response of bioink patterns, Escherichia coli contamination in fish fillets is identified within 16 h of needle injection. This response is distinct from spoilage measured via the increase in sample pH. It is also shown that the microneedles can pierce commercial food packaging, and subsequently sample fluid and present it to the sensor, enabling the adaptation of the technology downstream in food supply chains such as in stores or at home. This study highlights that regenerated structural biopolymers can serve as safe materials for food contact and sensing with robust mechanical properties and tailored chemistry.

Food Sensors: Challenges and Opportunities

“…In contrast, electronic sensors target the pH dependent electrical properties of a material. Both optical and electronic sensors are operated by submersion into the food, [ 23,24 ] sampling, [ 25 ] or absorption of gases released by the food. [ 26 ]…”

“…In contrast, electronic sensors target the pH dependent electrical properties of a material. Both optical and electronic sensors are operated by submersion into the food, [23,24] sampling, [25] or absorption of gases released by the food. [26] Recent advances have focused on materials to immobilize and encapsulate color indicators into packaging materials, such as paper and polymer matrices, [27][28][29] and synthesis of sensors from food waste streams.…”

“…Kim et al have recently reported a microneedle technology for sensing bacteria in food. [25] The technology exploits the capillary action of silk microneedles to sample fluid from food products and deliver it to PDA bioink sensors that have been functionalized with E. coli targeting antibodies. The authors demonstrated the technology can be used to monitor salmon by attachment of the system to the food product.…”

“…Reproduced with permission. [25] Copyright 2020, Wiley-VCH. www.advmattechnol.de particle size is critical to the performance of the technology or could be toxic.…”

Smart Microneedles for Therapy and Diagnosis

“…To fabricate porous microneedles, various approaches have been adopted, such as adding pore-forming agents to the prepolymers [ 60 , 61 ] and changing the structure of the polymer chain [ 62 ]. In a recent study, Kim et al used a “water annealing” method to modulate the polymorphism of their silk fibroin microneedles [ 63 ]. These microneedles were treated with water annealing for 4-8 h, and thus, their water solubility was decreased and fibrillar porous structures were increased.…”