Roman A Perez

• PhD
• Professor (Assistant) at Dankook University

The Electronic Nose (e-nose) is a growing tool widely used in food applications. This study classifies Sherry wines using an e-nose equipped with a matrix of gas sensors. By extracting features from identified phases of the sensor responses (slope, plateau, and ventilation) and applying the Elastic Net technique for feature selection, we improved m...

Bioceramics: Status in Tissue Engineering and Regenerative Medicine (Part 2) presents recent advancements in biocompatible ceramics and bioactive glasses, emphasizing their expanding applications in hard and soft tissue engineering. This book explores innovative manufacturing techniques like 3D printing and additive manufacturing and examines the t...

Among the different layers of the cornea, the corneal endothelium, which is composed of corneal endothelial cells (CEC), plays a key role in the maintenance of cornea transparency. Based on the donor shortages and the limitations associated with transplantation, in this work we have developed collagen hydrogels with different patterned structures o...

Silica-based scaffolds are promising in Tissue Engineering by enabling personalized scaffolds, boosting exceptional bioactivity and osteogenic characteristics. Moreover, silica materials are highly tunable, allowing for controlled drug release to enhance tissue regeneration. In this study, we developed a 3D printable silica material with controlled...

Silica 3D printable materials are interesting in bone tissue engineering as they allow the development of custom-made scaffolds with high bioactivity and osteogenic properties. However, all pure silica scaffolds nowadays require using a sintering step, which reduces the specific surface and porosity of the scaffolds, while limiting their biological...

Cells are able to respond to different physicochemical stimuli due to a complex molecular system that governs that response. The cell response to these stimuli can be translated into essential processes like cell survival, cell proliferation, cell differentiation, or protein synthesis. Cells need to respond to signals from their interactions, wheth...

The scaffold is one of the most important pillars of Tissue Engineering (TE). Therefore, it is very important to pay particular attention to their fabrication. Thus, in this chapter different scaffolds fabrication techniques are presented, going from the classical fabrication techniques to the most recent ones, such as 3D printing and 3D Bioprintin...

Soft tissue defects or pathologies frequently necessitate the use of biomaterials that provide the volume required for subsequent vascularization and tissue formation as autrografts are not always a feasible alternative. Supramolecular hydrogels represent promising candidates because of their 3D structure, which resembles the native extracellular m...

It is widely known that bone has intrinsic capacity to self-regenerate after injury. However, the physiological regeneration process can be impaired when there is an extensive damage. One of the main reasons is due to the inability to establish a new vascular network that ensures oxygen and nutrient diffusion, leading to a necrotic core and non-jun...

The influence of the surface topography of dental implants has been studied to optimize titanium surfaces in order to improve osseointegration. Different techniques can be used to obtain rough titanium, however, their effect on wettability, surface energy, as well as bacterial and cell adhesion and differentiation has not been studied deeply. Two-h...

One of the main problems in oral implantology today is peri-implantitis, which affects almost 20% of dental implants placed in patients. One of the most commonly used techniques to eliminate bacterial biofilm is the implantoplasty, that consists of the mechanical modification of the implant surface topography followed by treatments with chemical re...

Tissue defects can lead to serious health problems and often require grafts or transplants to repair damaged soft tissues. However, these procedures can be complex and may not always be feasible due to a lack of available tissue. Hydrogels have shown potential as a replacement for tissue grafts due to their ability to support cell survival and enca...

Tissue engineering focuses on the development of materials as biosubstitutes that can be used to regenerate, repair, or replace damaged tissues. Alongside this, 3D printing has emerged as a promising technique for producing implants tailored to specific defects, which in turn increased the demand for new inks and bioinks. Especially supramolecular...

Bone grafting is one of the most commonly performed treatments for bone healing or repair. Autografts, grafts from the same patient, are the most frequently used bone grafts because they can provide osteogenic cells and growth factors at the site of the implant with reduced risk of rejection or transfer of diseases. Nevertheless, this type of graft...

Supramolecular hydrogels are of great interest in tissue scaffolding, diagnostics, and drug delivery due to their biocompatibility and stimuli-responsive properties. In particular, nucleosides are promising candidates as building blocks due to their manifold noncovalent interactions and ease of chemical modification. Significant progress in the fie...

This study aimed to find the optimum mechanical characteristics of the restorative materials for the manufacture of implant crowns subjected to impact loading when different combinations of materials are used for the inner and outer crown. Several combinations of external–internal crown restorative materials were analyzed. The dynamic stresses at e...

Corneal endothelium defects are one of the leading causes of blindness worldwide. Actual treatment is transplantation, which requires the use of human cadaveric donors, but it faces several problems such as, global shortage of donors. Therefore, new alternatives are being developed and, among them, cell therapy has gained interest in the last years...

The techniques used in oral implantology to remove bacterial biofilm from the surface of implants by machining the titanium surface (implantoplasty) or by placing rough dental implants through friction with the cortical bone generate a large release of particles. In this work, we performed a simulation of particle generation following clinical prot...

Sol-gel silica-based hybrids combine an inorganic compound, silica, with an organic one to tune its properties for tissue regeneration. These hybrid materials can be produced at low temperature, which allow to encapsulate and release bioactive molecules, acting as a drug delivery system and enhancing tissue regeneration. In this study, tetraethyl o...

Cardiovascular diseases are considered one of the worldwide causes of death, with atherosclerosis being the most predominant. Nowadays, the gold standard treatment is blood vessel replacement by bypass surgery; however, autologous source is not always possible. Thereby, tissue-engineered blood vessels (TEBVs) are emerging as a potential alternative...

Macrophages have been deemed crucial for correct tissue regeneration, which is a complex process with multiple overlapping phases, including inflammation. Previous studies have suggested that divalent ions are promising cues that can induce an anti-inflammatory response, since they are stable cues that can be released from biomaterials. However, th...

The purpose of this research is to study the biomechanical response of dental implants in bone-level type locations, 0.5 mm above and below the bone level. In addition, the influence of the thickness of the cortical bone on osseointegration is determined due to the mechanical loads transfer from the dental implant to the cortical and trabecular bon...

The placement of bone–level dental implants can lead to the detachment of particles in the surrounding tissues due to friction with the cortical bone. In this study, 60 bone–level dental implants were placed with the same design: 30 made of commercially pure grade 4 titanium and 30 made of Ti6Al4V alloy. These implants were placed in cow ribs follo...

Objectives. The purpose of this work was to determine the influence of residual alumina after sand blasting treatment in titanium dental implants. This paper studied the effect of alumina on physico-chemical surface properties, such as: surface wettability, surface energy. Osseointegration and bacteria adhesion were determined in order to determine...

Bone has the intrinsic capacity to regenerate itself, as long as the damage is small, through the sequential stimulation of specific phases, such as angiogenesis followed by osteogenesis. However, when the damage is extensive it is unable to regenerate and bone tissue engineering is used as an alternative. In this study, we developed a platform to...

Bacterial infection of implanted scaffolds may have fatal consequences and, in combination with the emergence of multidrug bacterial resistance, the development of advanced antibacterial biomaterials and constructs is of great interest. Since decades ago, metals and their ions had been used to minimize bacterial infection risk and, more recently, m...

The use of copper (Cu²⁺) and cobalt (Co²⁺) has been described to stimulate blood vessel formation, a key process for the success of tissue regeneration. However, understanding how different concentrations of these ions affect cellular response is important to design scaffolds for their delivery to better fine tune the angiogenic response. On the on...

Biomaterials and scaffolds for Tissue Engineering are widely used for an effective healing and regeneration. However, the implantation of these scaffolds causes an innate immune response in which the macrophage polarization from M1 (pro-inflammatory) to M2 (anti-inflammatory) phenotype is crucial to avoid chronic inflammation. Recent studies have s...

Cardiovascular disease (CVD) is the leading cause of death among persons aged 65 and older in the United States and many other developed countries. Tissue engineered vascular systems (TEVS) can serve as grafts for CVD treatment and be used as in vitro model systems to examine the role of various genetic factors during the CVD progressions. Current...

Surface topography and physical-chemical properties usually play a key-role in both osseointegration improvement and bacterial colonization reduction over the surface of dental implants. The aim of this study is to compare the chemical and bacteriological behavior of two different acid passivation surface treatments on titanium c.p. grade 3 used fo...

Failure of corneal endothelium cell monolayer is the main cause leading to corneal transplantation. Autologous cell-based therapies are required to reconstruct in vitro the cell monolayer. Several strategies have been proposed using embryonic stem cells and induced pluripotent stem cells, although their use has ethical issues as well as limited cli...

Ion release from dental implants and prosthetic restoration can affect osteointegration and implant viability over a long period of time. Therefore, the aim of this study was to study the ion release from implants and crowns, with and without intermediate anodized abutments, in two different media, simulating clinical conditions. The implants, inte...

Bone is the most studied tissue in the field of tissue regeneration. Even though it has intrinsic capability to regenerate upon injury, several pathologies and injuries could hamper the highly orchestrated bone formation and resorption process. Bone tissue engineering seeks to mimic the extracellular matrix of the tissue and the different biochemic...

Although ceramic-on-ceramic (CoC) bearings have been shown to produce the smallest amount of wear volume in vitro as well as in vivo studies when used for total hip arthroplasties (THA), concerns about the failure of these bearing surfaces persist due to early failures observed after short postoperative time. In this study, an exhaustive analysis o...

Cardiovascular diseases (CVDs) are considered the principal cause of worldwide death, being atherosclerosis the main etiology. Up to now, the predominant treatment for CVDs has been bypass surgery from autologous source. However, due to previous harvest or the type of disease, this is not always an option. For this reason, tissue engineering blood...

Background: The delivery of growth factors using a carrier system presents a promising and innovative tool in tissue engineering and dentistry today. Two of the foremost bioactive factors, bone morphogenetic protein-2 and vascular endothelial growth factor (VEGF), are widely applied using a ceramic scaffold. The aim of this study was to determine...

The use of narrow titanium dental implants (NDI) for small ridges, reduced interdental space, or missing lateral incisors can be a viable option when compared to the conventional wider dental implants. Furthermore, in many cases, standard diameter implant placement may not be possible without grafting procedures, which increases the healing time, c...

The aim of this study was to evaluate the biomechanical behavior of Bone Level dental implants with four different neck designs in contact with cortical bone. Numerical simulations were performed using a Finite Element Method (FEM) based-model. In order to verify the FEM model, the in silico results were compared with the results obtained from hist...

The surface modifications of titanium dental implants play important roles in the enhancement of osseointegration. The objective of the present study was to test two different implant surface treatments on a rabbit model to investigate the osseointegration. The tested surfaces were: a) acid-etched surface with sandblasting treatment (SA) and b) an...

The poor correlation between in vitro and in vivo studies emphasises the lack of a reliable methodology for testing the biological properties of biomaterials in the bone tissue regeneration field. Moreover, the success of clinical trials is not guaranteed even with promising results in vivo. Therefore, there is a need for a more physiologically rel...

The load transfer from metallic prosthesis to tissue plays an important role in the success of a designed device. From a mechanical behavior point of view, the load transfer will be favored when the elastic modulus between the metallic implant and the bone tissue are similar. Titanium and Ti-6Al-4V are the most commonly used metals and alloys in th...

In this communication we report that anchoring αvβ3 or α5β1 integrin-selective RGD peptidomimetics to titanium efficiently tunes mesenchymal stem cell response in vitro and bone growth in rat calvarial defects....

Several dental implants are commercially available and new prototype design are constantly being fabricated. Nevertheless, it is still unclear what parameters of the design affect most the osseointegration of dental implants. The purpose of this study is to assess the effects of the microscopic and macroscopic design of dental implants in the osseo...

Statement of significance: 3D plotting has opened up new perspectives in the bone regeneration field allowing the customization of synthetic bone grafts able to fit patient-specific bone defects. Moreover, this technique allows the control of the scaffolds' architecture and porosity. The present work introduces a new method to harden biomimetic hy...

Background: The topographical features on the surface of dental implants have been considered as a critical parameter for enhancing the osseointegration of implants. In this work, we proposed a surface obtained by a combination of shot blasting and double acid etching. The double acid etching was hypothesized to increase the submicron topography a...

Objectives: The objective of this study was to assess, by histomorphometric analysis, the degree of bone apposition on two types of dental implant's surfaces: a novel implant that combines Al2O3 abrasive particle blasting with thermochemical treatment (ContacTi), compared to a standard surface treatment obtained by sandblasting and acid etching (s...

Biomedical cements are considered promising injectable materials for bone repair and regeneration. Calcium phosphate composition sized with tens of micrometers is currently one of the major powder forms. Here we report a unique cement form made from mesoporous bioactive glass nanoparticles (BGn). The nanopowder could harden in reaction with aqueous...

Silica-based nanomaterials (SiNMs) with different forms, including nanoparticles, nanorods and nanofibers either in dense, porous or hollow structure, have been fascinating platforms for the delivery of therapeutic molecules in the inorganic nanocarrier regime. This is primarily due to their unique physicochemical properties that are effective and...

Angiogenesis is considered an important issue in the development of biomaterials for the successful regeneration of tissues including bone. While growth factors are commonly used with biomaterials to promote angiogenesis, some ions released from biomaterials can also contribute to angiogenic events. Many silica-based biomaterials have been widely u...

The emerging regenerative medicine field has significant potential to change health care delivery in the 21st century. Primarily, stem cell culture methods and tissue engineering approaches typically adopted in biology labs are not scalable, yet scalability is key to ensuring commercial manufacturing success and delivery to clinic. An early example...

Regenerative approach has emerged to substitute the current extracorporeal technologies for the treatment of diseased and damaged liver tissue. This is based on the use of biomaterials that modulate the responses of hepatic cells through the unique matrix properties tuned to recapitulate regenerative functions. Cells in liver preserve their phenoty...

Providing an osteogenic stimulatory environment is a key strategy to construct stem cell-based bone-equivalent tissues. Here we design a stem cell delivering gel matrix made of collagen (Col) with bioactive glass nanocarriers (BGn) that incorporate osteogenic signaling molecule, fibroblast growth factor 18 (FGF18); a reservoir considered to cultiva...

This study focuses on the fatigue behavior and bone-implant attachment for the more usual surfaces of the different cp-titanium dental implants. The implants studied were: as-received (CTR), acid etching (AE), spark-anodization (SA) and with a grit-blasted surface (GB). Residual stresses were determined by means of X-ray diffraction. The fatigue te...

Intervertebral implants should be designed with low load requirements, high friction coefficient and low elastic modulus in order to avoid the stress shielding effect on bone. Furthermore, the presence of a highly interconnected porous structure allows stimulating bone in-growth and enhancing implant-bone fixation. The aim of this study was to obta...

Statement of significance: Organic coatings have been proposed as a solution to foster osseointegration of orthopedic implants. Among them, extracellular matrix-derived peptide motifs are an interesting biomimetic strategy to harness cell-surface interactions. Nonetheless, the combination of multiple peptide motifs in a controlled manner is essent...

Pluripotent stem cells (PSCs) derived from either the embryo or reprogramming processes have the capacity to self-renew and differentiate into various cells in the body, thereby offering a valuable cell source for regenerative therapy of intractable disease and serious tissue damage. Traditionally, methods to expand and differentiate PSCs have been...

Biomaterials in the form of scaffolds hold great promise in the regeneration of diseased tissues. The scaffolds stimulate cellular adhesion, proliferation and differentiation. While the scaffold composition will dictate their biocompatibility, their porosity plays a key role in allowing proper cell penetration, nutrient diffusion as well as bone in...

Nanotechnology has rapidly expanded into all areas of science; it offers significant alternative ways to solve scientific and medical questions and problems. In dentistry, nanotechnology has been exploited in the development of restorative materials with some significant success. This review discusses nanointerfaces that could compromise the longev...

Mouldable hydrogels that incorporate stem cells hold great promise for tissue engineering. They secure the encapsulated cells for required periods while allowing a permeable exchange of nutrients and gas with the surroundings. Core-shell fibrous structured hydrogel system represents these properties relevant to stem cell delivery and defect-adjusta...

Calcium phosphate cement (CPC) is a unique class of inorganic injectables attractive for the repair and regeneration of hard tissues. Tailoring the crystallite properties of CPC, particularly to represent nanotopological feature, is favorable for stimulating biological reactions. Nanotopological tailoring has recently been achieved on CPCs by simpl...

The osteogenic capacity of biomimetic calcium deficient hydroxyapatite microspheres with and without collagen obtained by emulsification of a calcium phosphate cement paste has been evaluated in an in vivo model, and compared with an injectable calcium phosphate cement with the same composition. The materials were implanted into a 5 mm defect in th...

Over the past few years, attention has been focused on the therapeutic roles in designing bone scaffolds for successful repair and regeneration. Indeed, biologically dynamic events in the bone healing process involve many of the molecules and cells adherent to the scaffold. Recent bone scaffolds have been designed considering intrinsic chemical and...

Unlabelled: Enabling early angiogenesis is a crucial issue in the success of bone tissue engineering. Designing scaffolds with therapeutic potential to stimulate angiogenesis as well as osteogenesis is thus considered a promising strategy. Here, we propose a novel scaffold designed to deliver angiogenic and osteogenic factors in a sequential manne...

Self-gelling/setting injectable biomaterials hold great promise for the delivery of bioactive molecules and cells useful for tissue engineering and regenerative medicine. In the biopolymeric regime, a broad compositional spectrum has been developed, yet very limited compositional options have been explored for inorganic injectables. For example, ca...

Scaffolds that secure and deliver therapeutic ingredients like signaling molecules and stem cells hold great promise for drug delivery and tissue engineering. Employing a core-shell design for scaffolds provides a promising solution. Some unique methods, such as co-concentric nozzle extrusion, microfluidics generation, and chemical confinement reac...

Partial polymerization during photolitho-graphy is precisely controlled to obtain a partially cured (PCP) layer on the formed 3D microstructures. Upon plasma treatment, a 3D surface with morphologically tunable and spatially controllable wrinkles is obtained. The fabrication process is characterized and its ability to make various wrinkled microstr...

Self-setting calcium phosphate cements (CPCs) are some of the few injectables of bioceramic materials applicable to bone repair. Incorporation of nanoparticulates to CPCs is considered a promising process that can improve the mechanical and biological properties of CPCs. Here, we added magnetic nanoparticles (MNPs) at small contents, and examined t...

Mechanical stimulation is an effective method to increase extracellular matrix synthesis and to improve the mechanical properties of tissue-engineered cartilage constructs. In this chapter, we describe valuable methods of imposing direct mechanical stimuli (compression or shear) to tissue-engineered cartilage constructs as well as some common analy...

Injectable calcium phosphate cements (CPCs) with strong mechanical properties and improved biological performance have the potential to be extensively used for bone regeneration. Although many additive materials have been incorporated to CPCs in order to achieve improvements in their mechanical and biological properties, somehow the results have no...

Periodontitis is an inflammatory disease that causes loss of the tooth-supporting apparatus, including periodontal ligament, cementum, and alveolar bone. A broad range of treatment options is currently available to restore the structure and function of the periodontal tissues. A regenerative approach, among others, is now considered the most promis...

Magnetism-induced applications of nanomaterials and scaffolds are currently gaining great interest for their potential applications in tissue repair and disease treatment. Here, we prepare novel magnetic scaffolds of a gelatin-siloxane (GS) hybrid for bone repair and regeneration by incorporating magnetite nanoparticles (MNs). MNs were incorporated...

Developing appropriate cell culturing techniques to populate scaffolds has become a great challenge in tissue engineering. This work describes the use of spinner flask dynamic cell cultures to populate hydroxyapatite microcarriers for bone tissue engineering. The microcarriers were obtained through the emulsion of a self-setting aqueous α-tricalciu...

Scaffolds with the capacity to deliver signaling molecules are attractive for bone regeneration. Here we developed bioactive siloxane-gelatin hybrid scaffolds via a sol gel process containing stromal derived factor-1 (SDF-1) to recruit osteoprogenitor/stem cells. The process was undertaken under room temperature aqueous conditions, which enabled th...

A novel therapeutic scaffolding system of engineered nanocarriers within a foam matrix for the long-term and sequential delivery of growth factors is reported. Mesoporous silica nanospheres were first functionalized to have an enlarged mesopore size (12.2 nm) and aminated surface, which was then shelled by a biopolymer, poly(lactic acid) (PLA) or p...

Three-dimensional matrices with controllable and sustainable delivery capacity of neurotrophic factors are promising platforms for neural tissue engineering. Here we developed a nerve growth factor (NGF) delivering cell culture system involving mesoporous silica nanoparticles (MSNs) combined with collagen hydrogel. Particularly for the loading of l...

Novel microcarriers made of sol-gel derived bioactive glasses were developed for delivering therapeutic molecules effectively while cultivating stem cells for bone tissue engineering. Silica sols with varying concentration of Ca (0-30% by mol) were formulated into microspheres ranging from 200 to 300 μm under optimized conditions. A highly mesoporo...

Drug molecules with lack of specificity and solubility lead patients to take high doses of the drug to achieve sufficient therapeutic effects. This is a leading cause of adverse drug reactions, particularly for drugs with narrow therapeutic window or cytotoxic chemotherapeutics. To address these problems, there are various functional biocompatible...

Three-dimensional matrices that encapsulate and deliver stem cells with defect-tuned formulations are promising for bone tissue engineering. Here we designed a novel stem cell delivery system composed of collagen and alginate as the core and shell, respectively. Mesenchymal stem cells (MSCs) were loaded into the collagen solution and then deposited...