Mehmet R Dokmeci

• Ph.D.
• Professor at University of California, Los Angeles

Skin-on-a-chip models provide physiologically relevant platforms for studying diseases and drug evaluation, replicating the native skin structures and functions more accurately than traditional 2D or simple 3D cultures. However, challenges remain in creating models suitable for microneedling applications and monitoring, as well as developing skin c...

Nanofibrous acoustic energy harvesters (NAEHs) have emerged as promising wearable platforms for efficient noise-to-electricity conversion in distributed power energy systems and wearable sound amplifiers for assistive listening devices. However, their real-life efficacy is hampered by low power output, particularly in the low-frequency range (< 1 k...

The global miniature devices market is poised to surpass a valuation of $12–$15 billion USD by the year 2030. Lab-on-a-chip (LOC) devices are a vital component of this market. Comprising a network of microchannels, electrical circuits, sensors, and electrodes, LOC is a miniaturized integrated device platform used to streamline day-to-day laboratory...

Several microfabrication technologies have been used to engineer native‐like skeletal muscle tissues. However, the successful development of muscle remains a significant challenge in the tissue engineering field. Muscle tissue engineering aims to combine muscle precursor cells aligned within a highly organized 3D structure and biological factors cr...

The tumor microenvironment consists of diverse, complex etiological factors. The matrix component of pancreatic ductal adenocarcinoma (PDAC) plays an important role not only in physical properties such as tissue rigidity but also in cancer progression and therapeutic responsiveness. Although significant efforts have been made to model desmoplastic...

Developing theranostic devices to detect bleeding and effectively control hemorrhage in the prehospital setting is an unmet medical need. Herein, an all‐in‐one theranostic platform is presented, which is constructed by sandwiching silk fibroin (SF) between two silver nanowire (AgNW) based conductive electrodes to non‐enzymatically diagnose local bl...

The contact lens (CL) industry has made great strides in improving CL‐wearing experiences. However, a large amount of CL wearers continue to experience ocular dryness, known as contact lens‐induced dry eye (CLIDE), stemming from the reduction in tear volume, tear film instability, increased tear osmolarity followed by inflammation and resulting in...

Within the complex microarchitecture of native cartilage tissue, the micromechanical properties of pericellular and extracellular matrices (PCM and ECM) potentially play important roles in developmental, physiological, and pathological processes. Here, we report a unique biomaterial-based engineering strategy to create cartilage-tissue equivalents...

Exosomes, a form of small extracellular vesicles, play a crucial role in the metastasis of cancers and thus are investigated as potential biomarkers for cancer diagnosis. However, conventional detection methods like immune‐based assay and microRNA analyses are expensive and require tedious pretreatments and lengthy analysis time. Since exosomes rel...

Silk fibroin (SF) is a promising biomaterial for tendon repair, but its relatively rigid mechanical properties and low cell affinity have limited its application in regenerative medicine. Meanwhile, gelatin‐based polymers have advantages in cell attachment and tissue remodeling but have insufficient mechanical strength to regenerate tough tissue su...

The eye is one of the most complex organs in the human body, containing rich and critical physiological information (e.g., intraocular pressure, corneal temperature, and pH) as well as a library of metabolite biomarkers (e.g., glucose, proteins, and specific ions). Smart contact lenses (SCLs) can serve as a wearable intelligent ocular prosthetic de...

Electrical stimulation can facilitate wound healing with high efficiency and limited side effects. However, current electrical stimulation devices have displayed poor conformability and coupling with wounds, due to their bulky nature and the rigidity of electrodes utilized. Here, a flexible electrical patch (ePatch) made with conductive hydrogel as...

Droplet-based microfluidic systems have been employed to manipulate discrete fluid volumes with immiscible phases. Creating the fluid droplets at microscale has led to a paradigm shift in mixing, sorting, encapsulation, sensing, and designing high throughput devices for biomedical applications. Droplet microfluidics has opened many opportunities in...

Wearable piezoresistive sensors are being developed as electronic skins (E‐skin) for broad applications in human physiological monitoring and soft robotics. Tactile sensors with sufficient sensitivities, durability, and large dynamic ranges are required to replicate this critical component of the somatosensory system. Multiple micro/nanostructures,...

Increasing evidence from cancer cell fusion with different cell types in the tumor microenvironment has suggested a probable mechanism for how metastasis-initiating cells could be generated in tumors. Although human mesenchymal stem cells (hMSCs) have been known as promising candidates to create hybrid cells with cancer cells, the role of hMSCs in...

Wearable piezoresistive sensors are being developed as electronic skins (e-skin) for broad applications in human physiological monitoring and soft robotics. Tactile sensors with sufficient sensitivities, durability, and large dynamic ranges are required to replicate this critical component of the somatosensory system. Multiple micro-/nano-structure...

The remarkable ability of biological systems to sense and adapt to complex environmental conditions has inspired new materials and novel designs for next-generation wearable devices. Hydrogels are being intensively investigated for their versatile functions in wearable devices due to their superior softness, biocompatibility, and rapid stimuli-resp...

Silver nanowires (AgNWs) hold great promise for applications in wearable electronics, flexible solar cells, chemical and biological sensors, photonic/plasmonic circuits, and scanning probe microscopy (SPM) due to their unique plasmonic, mechanical, and electronic properties. However, the lifetime, reliability, and operating conditions of AgNW-based...

Organ-on-a-chip (OoC) models are bioengineered tissue constructs integrated with microfluidics that recapitulate the key features of the physiology of human organs and tissues with applications related to drug development and personalized medicine. The characterization of OoCs relies on conventional labor-intensive approaches despite the many years...

The skin serves a substantial number of physiological purposes and is exposed to numerous biological and chemical agents owing to its large surface area and accessibility. Yet, current skin models are limited in emulating the multifaceted functions of skin tissues due to a lack of effort on the optimization of biomaterials and techniques at differe...

In article number 2007425, Junmin Lee, Ali Khademhosseini, and co‐workers present a breakthrough for modeling of non‐alcoholic fatty liver disease (NAFLD) based on bioengineered multicellular liver microtissues and a liver‐on‐a‐chip system. The microtissues consisting of four major liver cell types (primary human hepatocytes, stellate cells, Kupffe...

Despite considerable efforts in modeling liver disease in vitro, it remains difficult to recapitulate the pathogenesis of the advanced phases of non‐alcoholic fatty liver disease (NAFLD) with inflammation and fibrosis. Here, a liver‐on‐a‐chip platform with bioengineered multicellular liver microtissues is developed, composed of four major types of...

Cancer immunotherapies, including immune checkpoint inhibitor (ICI)‐based therapies, have revolutionized cancer treatment. However, patient response to ICIs is highly variable, necessitating the development of methods to quickly assess efficacy. In this study, an array of miniaturized bioreactors has been developed to model tumor‐immune interaction...

Wearable and implantable pressure sensors are in great demand for personalized health monitoring. Pressure sensors with low operation voltage and low power-consumption are desired for energy-saving devices. Organic iontronic devices, such as organic electrochemical transistors (OECTs), have demonstrated great potential for low power-consumptionbioe...

Wearable and implantable pressure sensors are in great demand for personalized health monitoring. Pressure sensors with low operation voltage and low power-consumption are desired for energy-saving devices. Organic iontronic devices, such as organic electrochemical transistors (OECTs), have demonstrated great potential for low power-consumption bio...

In article number 2003601, Shiming Zhang, Libo Zhao, Ali Khademhosseini, and co‐authors demonstrate a GelMA hydrogel biosensor capable of monitoring various human physiological signals. The device shows excellent stability. Robust chemical bonding and a reliable encapsulation approach are introduced to overcome detachment and water evaporation issu...

Fluorescent nanomaterials have been widely used in biological imaging due to their selectivity, sensitivity, and noninvasive nature. These characteristics make the materials suitable for real-time and in situ imaging. However, further development of highly biocompatible nanosystems with long-lasting fluorescent intensity and photostability is neede...

Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques. Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels t...

Gelatin methacryloyl (GelMA) is a widely used hydrogel with skin‐derived gelatin acting as the main constituent. However, GelMA has not been used in the development of wearable biosensors, which are emerging devices that enable personalized healthcare monitoring. This work highlights the potential of GelMA for wearable biosensing applications by de...

The skin houses a developed vascular and lymphatic network with a significant population of immune cells. Because of the properties of the skin, nucleic acid delivery through the tissue has the potential to treat a range of pathologies, including genetic skin conditions, hyperproliferative diseases, cutaneous cancers, wounds, and infections. This w...

Thrombosis is a life‐threatening pathological condition in which blood clots form in blood vessels, obstructing or interfering with blood flow. Thrombolytic agents (TAs) are enzymes that can catalyze the conversion of plasminogen to plasmin to dissolve blood clots. The plasmin formed by TAs breaks down fibrin clots into soluble fibrin that finally...

In article number 1900456, Han‐Jun Kim, Ali Khademhosseini, and co‐workers analyzed the swelling, degradation, microstructural, mechanical, rheological and biological properties of various compositions of composite hydrogels consisting of gelatin and silicate nanoplatelets (SNPs). Understanding of mechanical and biological consequences of the chang...

In article number 1901794, Ali Khademhosseini, Nureddin Ashammakhi, and co‐workers, present a novel approach to develop oxygenated bioinks, using oxygen generating calcium peroxide particles. Cardiomyocyte‐laden oxygenated and 3D printed tissue constructs developed in this study can significantly support cell survival when applied in hypoxic condit...

Separation of circulating tumor cells (CTCs) from blood samples and subsequent DNA extraction from these cells play a crucial role in cancer research and drug discovery. Microfluidics is a versatile technology that has been applied to create niche solutions to biomedical applications, such as cell separation and mixing, droplet generation, bioprint...

Cell survival during the early stages of transplantation and before new blood vessels formation is a major challenge in translational applications of 3D bioprinted tissues. Supplementing oxygen (O2) to transplanted cells via an O2 generating source such as calcium peroxide (CPO) is an attractive approach to ensure cell viability. Calcium peroxide a...

Cell separation is a key step in many biomedical research areas including biotechnology, cancer research, regenerative medicine, and drug discovery. While conventional cell sorting approaches have led to high‐efficiency sorting by exploiting the cell's specific properties, microfluidics has shown great promise in cell separation by exploiting diffe...

In article number 2000086, KangJu Lee, Ali Khademhosseini, and co‐workers present a novel device for enhancing wound healing, the detachable hybrid microneedle depot. It is the first device to use a microneedle array to facilitate localized mesenchymal stem cell delivery with a minimal dose of cells.

Mesenchymal stem cells (MSCs) have been widely used for regenerative therapy. In most current clinical applications, MSCs are delivered by injection but face significant issues with cell viability and penetration into the target tissue due to a limited migration capacity. Some therapies have attempted to improve MSC stability by their encapsulation...

Injectable shear‐thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varyin...

The detection of cardiac troponin I (cTnI) is clinically used to monitor myocardial infarctions (MI) and other heart diseases. The development of highly sensitive detection assays for cTnI is needed for the efficient diagnosis and monitoring of cTnI levels. Traditionally, enzyme-based immunoassays have been used for the detection of cTnI. However,...

Patterning of conducting polymer poly(3,4)ethylenedioxythiophene doped with polystyrene sulfonate (PEDOT:PSS) thin films directly on hydrophobic soft substrates is challenging. Shiming Zhang, Ali Khademhosseini, and co‐workers, in article number 1906016, report that hydrogels are capable of transfer‐printing patterned PEDOT:PSS thin films from glas...

Minimally invasive biosensors are emerging as powerful tools to enable personalized healthcare and precision medicine. Recent advances in biotechnology, wireless communication, and flexible electronics have offered unprecedented opportunity to develop minimally invasive biosensors for commercial applications. In this chapter, we discuss emerging te...

Currently, there are more than 1.5 million knee and hip replacement procedures carried out in the United States. Implants have a 10–15-year lifespan with up to 30% of revision surgeries showing complications with osteomyelitis. Titanium and titanium alloys are the favored implant materials because they are lightweight and have high mechanical stren...

In article number 1904752, Shiming Zhang, Ali Khademhosseini, and co‐workers demonstrate that an injectable conducting polymer poly(3,4‐ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) hydrogel fiber can be achieved by crosslinking a PEDOT:PSS suspension at room temperature in a tube. The hydrogel fiber can be extruded by pressurizing th...

Microphysiological systems, also known as organ‐on‐a‐chip platforms, are increasingly poised to replace costly animal studies. The utilization of integrated multiorgan‐on‐a‐chip systems for advancing nanotechnology will be reflected in future drug development, toxicology studies, and precision medicine. In article number 1900589 by Nureddin Ashamma...

Microneedles (MNs) have been used to deliver drugs for over two decades. These platforms have been proven to dramatically increase transdermal drug delivery efficiency by penetrating restrictive tissue barriers in a minimally invasive manner. While much of the early development of MNs focused on transdermal drug delivery, this technology can be app...

In article number 1901379, Junmin Lee, Ali Khademhosseini, and co‐workers, develop an in vitro human liver model of non‐alcoholic fatty liver disease (NAFLD) by co‐culturing human hepatocytes, umbilical vein endothelial cells (HUVECs), and Kupffer cells (KCs) into spheroids. The proposed system is an appropriate model to mimic and monitor the progr...

The use of conducting polymers such as poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) for the development of soft organic bioelectronic devices, such as organic electrochemical transistors (OECTs), is rapidly increasing. However, directly manipulating conducting polymer thin films on soft substrates remains challenging, which hi...

The liver has a complex and unique microenvironment with multiple cell–cell interactions and internal vascular networks. Although nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease with multiple phases, no proper model could fully recapitulate the in vivo microenvironment to understand NAFLD progression. Here, an in v...

Microphysiological systems, also known as organ‐on‐a‐chip platforms, show promise for the development of new testing methods that can be more accurate than both conventional two‐dimensional (2D) cultures and costly animal studies. The development of more intricate microphysiological systems can help to better mimic the human physiology and highligh...

There is an increasing need to develop conducting hydrogels for bioelectronic applications. In particular, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogels have become a research hotspot due to their excellent biocompatibility and stability. However, injectable PEDOT:PSS hydrogels have been rarely reported. Such syringe...

In article number 1900104, Junmin Lee, Ali Khademhosseini, and co‐workers develop a bioengineered liver steatosis model based on the interactions between human hepatocytes and primary human endothelial cells by forming multicellular aggregates to investigate steatosis pathogenesis. The spheroids on a chip platform can be used for monitoring hepatoc...

Three-dimensional (3D) printing technology has received great attention in the past decades in both academia and industry because of its advantages such as customized fabrication, low manufacturing cost, unprecedented capability for complex geometry, and short fabrication period. 3D printing of metals with controllable structures represents a state...

Understanding complex cell–cell interactions and physiological microenvironments is critical for the development of new therapies for treating human diseases. Current animal models fail to accurately predict success of therapeutic compounds and clinical treatments. Advances in biomaterials, engineering, and additive manufacturing have led to the de...

Oxygen (O2) generating biomaterials are emerging as important compositions to improve our capabilities in supporting tissue engineering and regenerative therapeutics. Several in vitro studies demonstrated the usefulness of O2 releasing biomaterials in enhancing cell survival and differentiation. However, more efforts are needed to develop materials...

The liver possesses a unique microenvironment with a complex internal vascular system and cell–cell interactions. Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease, and although much effort has been dedicated to building models to target NAFLD, most in vitro systems rely on simple models failing to recapitula...

Each person's response to the therapies is different. In article number 1801039, Ali Khademhosseini and co‐workers discuss engineering approaches for precision medicine. Healthcare could be individualized through personalized cells therapies, controlled drug delivery systems, personalized scaffolds and implants, wearable sensors, point‐of‐care devi...

Advances in microscale fabrication techniques have enabled novel therapeutics to be developed (cells, biomaterials, biomolecules or their combinations), delivered to the body via minimally invasive procedures. These therapeutics can be used to help regenerate various tissues, with lower risk of complications, reduced cost, and improved outcome, and...

Advances in biomaterial synthesis and fabrication, stem cell biology, bioimaging, microsurgery procedures, and microscale technologies have made minimally invasive therapeutics a viable tool in regenerative medicine. Therapeutics, herein defined as cells, biomaterials, biomolecules, and their combinations, can be delivered in a minimally invasive w...

Advances in genomic sequencing and bioinformatics have led to the prospect of precision medicine where therapeutics can be advised by the genetic background of individuals. For example, mapping cancer genomics has revealed numerous genes that affect the therapeutic outcome of a drug. Through materials and cell engineering, many opportunities exist...

In article number 1703509, Ali Tamayol, Sameer R. Sonkusale, Ali Khademhosseini, and co‐workers engineer a smart flexible wound dressing with integrated temperature and pH sensors onto flexible bandages that monitor wound healing status in real‐time for the treatment of chronic wounds. The flexible and wearable platform allows on‐demand drug delive...

Chronic wounds are a major health concern and they affect the lives of more than 25 million people in the United States. They are susceptible to infection and are the leading cause of nontraumatic limb amputations worldwide. The wound environment is dynamic, but their healing rate can be enhanced by administration of therapies at the right time. Th...

A stereolithography‐based bioprinting platform for multimaterial fabrication of heterogeneous tissue constructs is developed in article number 1800242, by Yu Shrike Zhang, Ali Khademhosseini, and co‐workers. This is realized through dynamic patterning by a digital micro‐mirror device synchronized by a moving stage and a microfluidic device containi...

A stereolithography‐based bioprinting platform for multimaterial fabrication of heterogeneous hydrogel constructs is presented. Dynamic patterning by a digital micromirror device, synchronized by a moving stage and a microfluidic device containing four on/off pneumatic valves, is used to create 3D constructs. The novel microfluidic device is capabl...

Bioprinting is an emerging technology with various applications in making functional tissue constructs to replace injured or diseased tissues. It is a relatively new approach that provides high reproducibility and precise control over the fabricated constructs in an automated manner, potentially enabling high-throughput production. During the biopr...

Efficient methods for the accurate analysis of drug toxicities are in urgent demand as failures of newly discovered drug candidates due to toxic side effects have resulted in about 30% of clinical attrition. The high failure rate is partly due to current inadequate models to study drug side effects, i.e., common animal models may fail due to its mi...

To create life-like movements, living muscle actuator technologies have borrowed inspiration from biomimetic concepts in developing bioinspired robots. Here, the development of a bioinspired soft robotics system, with integrated self-actuating cardiac muscles on a hierarchically structured scaffold with flexible gold microelectrodes is reported. In...

Many drugs have progressed through preclinical and clinical trials and have been available – for years in some cases – before being recalled by the FDA for unanticipated toxicity in humans. One reason for such poor translation from drug candidate to successful use is a lack of model systems that accurately recapitulate normal tissue function of hum...

Delivery of drugs with controlled temporal profiles is essential for wound treatment and regenerative medicine applications. For example, bacterial infection is a key challenge in the treatment of chronic and deep wounds. Current treatment strategies are based on systemic administration of high doses of antibiotics, which result in side effects and...

There is a critical need to develop fabrication methods for rapid and cost-effective prototyping of thermoplastics-based microfluidics in academic research laboratories. This paper presents a method for the fabrication of whole-thermoplastic microfluidic functional elements, including a pneumatic (gas-actuated) normally closed microvalve, a micro-c...

Tissue engineering has emerged as a viable approach to treat disease or repair damage in tissues and organs. One of the key elements for the success of tissue engineering is the use of a scaffold serving as artificial extracellular matrix (ECM). The ECM hosts the cells and improves their survival, proliferation, and differentiation, enabling the fo...

Chronic wounds do not heal in an orderly fashion in part due to the lack of timely release of biological factors essential for healing. Topical administration of various therapeutic factors at different stages is shown to enhance the healing rate of chronic wounds. Developing a wound dressing that can deliver biomolecules with a predetermined spati...