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Ultraminiaturized neural implanted constructs display minimal immunologic response
KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.ORCID iD: 0000-0003-1235-9099
Karolinska Inst, Dept Clin Neurosci, Stockholm, Sweden.
KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.ORCID iD: 0009-0003-4252-9973
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2025 (English)In: MATERIALS TODAY BIO, ISSN 2590-0064, Vol. 32, article id 101819Article in journal (Refereed) Published
Abstract [en]

Biocompatibility of medical implants poses a significant challenge in medical technology. Neural implants, integral to curative therapies, initially exhibit efficacy but can lead to unforeseen long-term side effects. The material composition and dimensions of implants are critical factors influencing their biocompatibility within brain tissue. Typically, neural implants are identified as foreign entities by the patient's immune system, triggering persistent inflammation and severe adverse effects. In this study, we investigate the host response in mouse brain tissue of implanted microscale constructs measuring 0.1 x 0.1 x 1 mm3 fabricated from common microfabrication materials. Magnetic Resonance Imaging (MRI) analysis reveals rapid recovery of brain parenchyma at 6 week interval post-implantation, accompanied by negligible or mild adverse immune responses during the experimental period. Histological assessments and cell marker stainings targeting astroglia, macrophages, and microglia demonstrate minimal impacts of the microconstructs on mouse brain tissue throughout the 24-week implantation period. Our findings indicate that untethered microimplants of this scale may have potential applications in medical technology and medical treatment for various brain diseases. In summary, this study supports the development of potentially biocompatible brain microimplants that could be useful for the long-term management of chronic brain disorders.

Place, publisher, year, edition, pages
Elsevier BV , 2025. Vol. 32, article id 101819
Keywords [en]
Biocompatibility, Microimplants, Fabrication, Brain, Constructs
National Category
Neurosciences
Identifiers
URN: urn:nbn:se:kth:diva-364053DOI: 10.1016/j.mtbio.2025.101819ISI: 001487034500001PubMedID: 40391020Scopus ID: 2-s2.0-105003918976OAI: oai:DiVA.org:kth-364053DiVA, id: diva2:1962923
Note

QC 20250602

Available from: 2025-06-02 Created: 2025-06-02 Last updated: 2025-11-06Bibliographically approved
In thesis
1. Unorthodox mechanical microsystems for drug delivery
Open this publication in new window or tab >>Unorthodox mechanical microsystems for drug delivery
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Microelectromechanical systems (MEMS) offer powerful solutions for drug delivery where biological barriers limit the potential of advanced therapeutics. This thesis demonstrates how unorthodox applications of microfabrication techniques can create novel platforms to overcome drug delivery challenges, enhancing the delivery of potent and fragile biologics.

The first part of this work focuses on implantable systems. An ultrasonically actuated micro-implant is presented, which exploits mechanical resonance not for sensing but for the selective, on demand destruction of reservoir membranes. This enables remotely triggered drug release without onboard power or electronics. Building on this, a miniaturized ultrasonic energy harvester is developed, integrating a high-performance, bulk piezoelectric material (PZT-5H) via a novel low-temperature bonding process, creating a robust power source for future active implants.

The second part explores two-photon polymerization (2PP) to fabricate complex 3D microstructures for non-invasive delivery. First, rolling ultra-miniaturized microneedle spheres (RUMS) are introduced. Unlike traditional flat microneedle patches, these 3D particles are suspended in topical formulations to gently and repeatedly disrupt the skin’s stratum corneum, enabling the effective transdermal delivery of biologics. Second, a micro-swirl nozzle, a design typically found in internal combustion or agricultural applications, has been developed to aerosolize fragile biologics. This geometry generates a fine mist suitable for deep lung deliverythrough a low-shear mechanism, preserving the integrity of sensitive payloads like lipid nanoparticle (LNP)-encapsulated mRNA.

Collectively, this work showcases a versatile approach to biomedical engineering, where the precise control of micro-scale geometry and physics is leveraged to solve persistent challenges in therapeutic delivery.

Abstract [sv]

Mikroelektromekaniska system (MEMS) erbjuder nya effektiva lösningar för läkemedelstillförsel där biologiska barriärer hindrar den kliniska potentialen hos avancerade terapier. Denna avhandling visar hur oortodoxa tillämpningar av mikrofabrikationstekniker kan skapa nya plattformar för att överkomma läkemedelstillförsel utmaningar och förbättra tillförsel av potenta och ömtåliga biologiska läkemedel.

Den första delen av detta arbete fokuserar på implanterbara system. Ett ultraljudsaktiverat mikroimplantat presenteras som utnyttjar mekanisk resonans, inte för avkänning, utan för selektiv, on-demand destruktion av reservoarmembran. Detta möjliggör fjärrstyrd läkemedelsfrisättning utan någon inbyggd strömförsörjning eller elektronik. Baserat på samma teknik har en miniatyriserad ultraljudsenergiuppsamlare utvecklats. Den integrerar ett högpresterande, bulk-piezoelektriskt material (PZT-5H) via en ny lågtemperaturbindningsprocess, vilket skapar en robust strömkälla för framtida aktiva implantat.

Den andra delen utav arbetet utforskar tvåfotonpolymerisation (2PP) för att tillverka komplexa 3D-mikrostrukturer för icke-invasiv läkemedelstillförsel. Först introduceras rullande ultraminiatyriserade mikronålssfärer (RUMS). Till skillnad från traditionella platta mikronålsplåster är dessa 3D-partiklar suspenderade i topiska formuleringar för att skonsamt och upprepat bryta hudens hornlager, vilket möjliggör effektiv leverans av biologiska läkemedel genom huden av. Vidare har ett mikrovirvelmunstycke, en design som vanligtvis återfinns i förbränningsmotorer eller i jordbrukstillämpningar, utvecklats för att aerosolisera ömtåliga biologiska läkemedel. Geometrin hos munstycket genererar en fin dimma som är lämplig för djup lungadministrering genom en lågskjuvningsmekanism. Detta bevarar integriteten hos läkemedel med känsliga laster såsom lipid nanopartikel (LNP)-inkapslat mRNA.

Sammantaget visar detta arbete användbara och mångsidiga tillvägagångssätt inom medicinsk teknik, där precis kontroll av mikroskalig geometri och fysik utnyttjas för att lösa svåra utmaningar inom läkemedelstillförsel.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2025. p. xii, 85
Series
TRITA-EECS-AVL ; 2025:101
Keywords
Ulrasound, Piezoelectric, Energy Harvesting, Microneedles, Soft Mist Inhaler, Drug delivery, Biologics, 2-photon, additive manufacturing, MEMS, Ultraljud, Piezoelektrisk, Energiutvinning, Mikronålar, Soft Mist Inhalator, Läkemedelstillförsel, Biologiska läkemedel, 2-foton, additiv tillverkning, MEMS
National Category
Medical Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Medical Technology
Identifiers
urn:nbn:se:kth:diva-372432 (URN)978-91-8106-455-1 (ISBN)
Public defence
2025-12-19, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20251107

Available from: 2025-11-07 Created: 2025-11-06 Last updated: 2025-12-15Bibliographically approved

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Spyrou, ArgyrisSandell, MikaelIordanidis, Theocharis N.Stemme, GöranRoxhed, Niclas

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