Immobilization of carbonic anhydrase on spherical SBA-15 for hydration and sequestration of CO2

Simulation Study of Carbonic Anhydrase Adsorption on Self-Assembled Monolayers

Carbonic anhydrase (CA) is a zinc-containing metalloenzyme that can rapidly catalyze the interconversion of CO2 and bicarbonate under suitable conditions. In industrial applications such as carbon capture, the performance of immobilized CA is highly related to its adsorption orientation and conformational changes on different carrier surfaces. In this work, the combined simulations of Parallel Tempering Monte Carlo and all-atom molecular dynamics were employed to uncover the adsorption mechanisms, orientations, and conformational changes of CA on charged self-assembled monolayers with different surface charge densities. The simulation results demonstrate that the adsorption of CA on charged surfaces is dominated by electrostatic interactions and influenced by the distribution of charged areas on the surface. CA adsorbs on the NH2-SAM surfaces with a ″bottom-on″ orientation with its active pocket facing the solution, which is beneficial for the catalytic process of CA. Asp160 was identified as a common adsorption residue for CA on NH2-SAM surfaces with different SCDs. Furthermore, the native structure of CA is well preserved after adsorption on the NH2-SAM surface, which is advantageous for the recovery of the catalytic activity of immobilized CA. In summary, this work elucidates the role of surface charge in regulating the adsorption orientation of carbonic anhydrase and its conformational changes during the adsorption process at the molecular level and provides theoretical guidance for the design of CA-based biocatalysts.

Biosilica-coated carbonic anhydrase displayed on Escherichia coli: A novel design approach for efficient and stable biocatalyst for CO2 sequestration

A robust and stable carbonic anhydrase (CA) system is indispensable for effectively sequestering carbon dioxide to mitigate climate change. While microbial surface display technology has been employed to construct an economically promising cell-displayed CO2-capturing biocatalyst, the displayed CA enzymes were prone to inactivation due to their low stability in harsh conditions. Herein, drawing inspiration from biomineralized diatom frustules, we artificially introduced biosilica shell materials to the CA macromolecules displayed on Escherichia coli surfaces. Specifically, we displayed a fusion of CA and the diatom-derived silica-forming Sil3K peptide (CA-Sil3K) on the E. coli surface using the membrane anchor protein Lpp-OmpA linker. The displayed CA-Sil3K (dCA-Sil3K) fusion protein underwent a biosilicification reaction under mild conditions, resulting in nanoscale self-encapsulation of the displayed enzyme in biosilica. The biosilicified dCA-Sil3K (BS-dCA-Sil3K) exhibited improved thermal, pH, and protease stability and retained 63 % of its initial activity after ten reuses. Additionally, the BS-dCA-Sil3K biocatalyst significantly accelerated the CaCO3 precipitation rate, reducing the time required for the onset of CaCO3 formation by 92 % compared to an uncatalyzed reaction. Sedimentation of BS-dCA-Sil3K on a membrane filter demonstrated a reliable CO2 hydration application with superior long-term stability under desiccation conditions. This study may open new avenues for the nanoscale-encapsulation of enzymes with biosilica, offering effective strategies to provide efficient, stable, and economic cell-displayed biocatalysts for practical applications.

Immobilization of carbonic anhydrase on modified PES membranes for artificial lungs

The introduction of carbonic anhydrase (CA) onto an extracorporeal membrane oxygenation (ECMO) membrane can improve the permeability of carbon dioxide (CO2). However, existing CA-grafting methods have limitations, and the hemocompatibility of current substrate membranes of commercial ECMO is not satisfactory. In this study, a 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxy succinimide (NHS) activation method is adopted to graft CA with CO2-catalyzed conversion activity onto a polyethersulfone (PES) membrane, which is prepared by a phase inversion technique after in situ crosslinking polymerization of 1-vinyl-2-pyrrolidone (VP) and acrylic acid (AA) in PES solution. The characterization results reveal that CA has been grafted onto the modified PES membrane successfully and exhibits catalytic activity. The kinetic parameters of esterase activity verify that the grafted amount of active CA increases with an increase in the concentration of the CA incubation solution. The CA-grafted membrane (CA-M) can accelerate the conversion of bicarbonate to CO2 in water and blood, which demonstrates the special catalytic activity towards bicarbonate of CA. Finally, blood compatibility tests prove that the CA-M does not lead to hemolysis, shows suppressed protein adsorption and increased coagulation time, and is suitable for application in ECMO. This work demonstrates a green and efficient method for preparing bioactive materials and has practical guiding significance for subsequent pulmonary membrane research and ECMO applications.

Direct Biocatalytic Processes for CO2 Capture as a Green Tool to Produce Value-Added Chemicals

Direct biocatalytic processes for CO₂ capture and transformation in value-added chemicals may be considered a useful tool for reducing the concentration of this greenhouse gas in the atmosphere. Among the other enzymes, carbonic anhydrase (CA) and formate dehydrogenase (FDH) are two key biocatalysts suitable for this challenge, facilitating the uptake of carbon dioxide from the atmosphere in complementary ways. Carbonic anhydrases accelerate CO₂ uptake by promoting its solubility in water in the form of hydrogen carbonate as the first step in converting the gas into a species widely used in carbon capture storage and its utilization processes (CCSU), particularly in carbonation and mineralization methods. On the other hand, formate dehydrogenases represent the biocatalytic machinery evolved by certain organisms to convert CO₂ into enriched, reduced, and easily transportable hydrogen species, such as formic acid, via enzymatic cascade systems that obtain energy from chemical species, electrochemical sources, or light. Formic acid is the basis for fixing C₁-carbon species to other, more reduced molecules. In this review, the state-of-the-art of both methods of CO₂ uptake is assessed, highlighting the biotechnological approaches that have been developed using both enzymes.

Carbonic anhydrase as a tool to mitigate global warming

The global average temperature breaks the record every year, and this unprecedented speed at which it is unfolding is causing serious climate change which in turn impacts the lives of humans and other living organisms. Thus, it is imperative to take immediate action to limit global warming. Increased CO2 emission from the industrial sector that relies on fossil fuels is the major culprit. Mitigating global warming is an uphill battle that involves an integration of technologies such as switching to renewable energy, increasing the carbon sink capacity, and implementing carbon capture and sequestration (CCS) on major sources of CO2 emissions. Among all these methods, CCS is globally accepted as a potential technology to address this climate change. CCS using carbonic anhydrase (CA) is gaining momentum due to its advantages over other conventional CCS technologies. CA is a metalloenzyme that catalyses a fundamental reaction for life, i.e. the interconversion of bicarbonate and protons from carbon dioxide and water. The practical application of CA requires stable CAs operating under harsh operational conditions. CAs from extremophilic microbes are the potential candidates for the sequestration of CO2 and conversion into useful by-products. The soluble free form of CA is expensive, unstable, and non-reusable in an industrial setup. Immobilization of CA on various support materials can provide a better alternative for application in the sequestration of CO2. The present review provides insight into several types of CAs, their distinctive characteristics, sources, and recent developments in CA immobilization strategies for application in CO2 sequestration.

Immobilization of carbonic anhydrase for CO2 capture and utilization

Carbonic anhydrase (CA) is an excellent candidate for novel biocatalytic processes based on the capture and utilization of CO₂. The setup of efficient methods for enzyme immobilization makes CA utilization in continuous bioreactors increasingly attractive and opens up new opportunities for the industrial use of CA. The development of efficient processes for CO₂ capture and utilization (CCU) is one of the most challenging targets of modern chemical reaction engineering. In the general frame of CCU processes, the interest in the utilization of immobilized CA as a biocatalyst for augmentation of CO₂ reactive absorption has grown consistently over the last decade. The present mini-review surveys and discusses key methodologies for CA immobilization aimed at the development of heterogeneous biocatalysts for CCU. Advantages and drawbacks of covalent attachment on fine granular solids, immobilization as cross-linked enzyme aggregates, and "in vivo" immobilization methods are presented. In particular, criteria for optimal selection of CA-biocatalyst and design of CO₂ absorption units are presented and discussed to highlight the most effective solutions. Perspectives on biocatalytic CCU processes that can include the use of CA in an enzymatic reactive CO₂ absorption step are eventually presented with a special focus on two examples of CO₂ fixation pathways: hybrid enzyme-microalgae process and enzyme cascade for the production of carboxylic acids. KEY POINTS: • Covalent immobilization techniques applied to CA are effective for CO₂ ERA. • Biocatalyst type and morphology must be selected considering CO₂ ERA conditions. • Immobilized CA can offer novel routes to CO₂ capture and direct utilization.

Design of a Superpositively Charged Enzyme: Human Carbonic Anhydrase II Variant with Ferritin Encapsulation and Immobilization

Supercharged proteins exhibit high solubility and other desirable properties, but no engineered superpositively charged enzymes have previously been made. Superpositively charged variants of proteins such as green fluorescent protein have been efficiently encapsulated within Archaeoglobus fulgidus thermophilic ferritin (AfFtn). Encapsulation by supramolecular ferritin can yield systems with a variety of sequestered cargo. To advance applications in enzymology and green chemistry, we sought a general method for supercharging an enzyme that retains activity and is compatible with AfFtn encapsulation. The zinc metalloenzyme human carbonic anhydrase II (hCAII) is an attractive encapsulation target based on its hydrolytic activity and physiologic conversion of carbon dioxide to bicarbonate. A computationally designed variant of hCAII contains positively charged residues substituted at 19 sites on the protein's surface, resulting in a shift of the putative net charge from -1 to +21. This designed hCAII(+21) exhibits encapsulation within AfFtn without the need for fusion partners or additional reagents. The hCAII(+21) variant retains esterase activity comparable to the wild type and spontaneously templates the assembly of AfFtn 24mers around itself. The AfFtn-hCAII(+21) host-guest complex exhibits both greater activity and thermal stability when compared to hCAII(+21). Upon immobilization on a solid support, AfFtn-hCAII(+21) retains enzymatic activity and exhibits an enhancement of activity at elevated temperatures.

Impact of heteroatom addition into mesoporous silica for water adsorption in the low partial pressure range

Mesoporous silicas are known to be high-performing water adsorbents in high humidity levels due to their large pore volumes. However, for low humidity conditions, these materials typically present a less expressive performance, which is a drawback for many applications. In the present report, mesoporous silica SBA-15 was functionalized with Al, Ti, Zr and Li in order to improve their performance in this condition. The influence of functionalization in porosity, morphology and acidic sites was investigated. Samples with an increased number of acidic sites and with higher microporosity when compared to pure silica were produced. This was responsible for their enhanced performance for water adsorption in low moisture conditions. Sample functionalized with zirconium in SBA-15 synthesis improved the water adsorption capacity of pure silica by three times, reaching up to 127 g kg⁻¹ at a relative pressure of 0.2 and 570 g kg⁻¹ close to saturation pressure. This sample was found to be a promising material to be applied in processes which require high adsorption capacities in both low and high water partial pressure ranges. Moreover, the understanding of the mechanisms behind the heteroatom functionalization can be applied to any silica material in order to enhance its attractiveness towards any polar molecule.

Carbonic anhydrase modification for carbon management

Carbonic anhydrase modification (chemical and biological) is an attractive strategy for its diverse application to accelerate the absorption of CO₂ from a flue gas with improved activity and stability. This article reports various possibilities of CA modification using metal-ligand homologous chemistry, cross-linking agents, and residue- and group-specific and genetic modifications, and assesses their role in carbon management. Chemically modified carbonic anhydrase is able to improve the absorption of carbon dioxide from a gas stream into mediation compounds with enhanced sequestration and mineral formation. Genetically modified CA polypeptide can also increase carbon dioxide conversion. Chemical modification of CA can be categorized in terms of (i) residue-specific modification (involves protein-ligand interaction in terms of substitution/addition) and group-specific modifications (based on the functional groups of the target CA). For every sustainable change, there should be no/limited toxic or immunological response. In this review, several CA modification pathways and biocompatibility rules are proposed as a theoretical support for emerging research in this area.

Bioconversion of xylose to xylonic acid via co-immobilized dehydrogenases for conjunct cofactor regeneration

Enzymatic cofactor-dependent conversion of monosaccharides can be used in the bioproduction of value-added compounds. In this study, we demonstrate co-immobilization of xylose dehydrogenase (XDH, EC 1.1.1.175) and alcohol dehydrogenase (ADH, EC 1.1.1.1) using magnetite-silica core-shell particles for simultaneous conversion of xylose into xylonic acid (XA) and in situ cofactor regeneration. The reaction conditions were optimized by factorial design, and were found to be: XDH:ADH ratio 2:1, temperature 25 °C, pH 7, and process duration 60 min. Under these conditions enzymatic production of xylonic acid exceeded 4.1 mM and was more than 25% higher than in the case of a free enzymes system. Moreover, the pH and temperature tolerance as well as the thermo- and storage stability of the co-immobilized enzymes were significantly enhanced. Co-immobilized XDH and ADH make it possible to obtain higher xylonic acid concentration over broad ranges of pH (6-8) and temperature (15-35 °C) as compared to free enzymes, and retained over 60% of their initial activity after 20 days of storage. In addition, the half-life of the co-immobilized system was 4.5 times longer, and the inactivation constant (k_D = 0.0141 1/min) four times smaller, than those of the free biocatalysts (k_D = 0.0046 1/min). Furthermore, after five reaction cycles, immobilized XDH and ADH retained over 65% of their initial properties, with a final biocatalytic productivity of 1.65 mM of xylonic acid per 1 U of co-immobilized XDH. The results demonstrate the advantages of the use of co-immobilized enzymes over a free enzyme system in terms of enhanced activity and stability.

Extracorporeal carbon dioxide removal (ECCO2R) in respiratory deficiency and current investigations on its improvement: a review

The implementation of extracorporeal carbon dioxide removal (ECCO₂R) as one of the extracorporeal life support system is getting more attention today. Thus, the objectives of this paper are to study the clinical practice of commercial ECCO₂R system, current trend of its development and also the perspective on future improvement that can be done to the existing ECCO₂R system. The strength of this article lies in its review scope, which focuses on the commercial ECCO₂R therapy in the market based on membrane lung and current investigation to improve the efficiency of the ECCO₂R system, in terms of surface modification by carbonic anhydrase (CA) immobilization technique and respiratory electrodialysis (R-ED). Our methodology approach involves the identification of relevant published literature from PubMed and Web of Sciences search engine using the terms Extracorporeal Carbon Dioxide Removal (ECCO₂R), Extracorporeal life support, by combining terms between ECCO₂R and CA and also ECCO₂R with R-ED. This identification only limits articles in English language. Overall, several commercial ECCO₂R systems are known and proven safe to be used in patients in terms of efficiency, safety and risk of complication. In addition, CA-modified hollow fiber for membrane lung and R-ED are proven to have good potential to be applied in conventional ECCO₂R design. The detailed technique and current progress on CA immobilization and R-ED development were also reviewed in this article.

Accelerating Mineral Carbonation Using Carbonic Anhydrase

Carbonic anhydrase (CA) enzymes have gained considerable attention for their potential use in carbon dioxide (CO2) capture technologies because they are able to catalyze rapidly the interconversion of aqueous CO2 and bicarbonate. However, there are challenges for widespread implementation including the need to develop mineralization process routes for permanent carbon storage. Mineral carbonation of highly reactive feedstocks may be limited by the supply rate of CO2. This rate limitation can be directly addressed by incorporating enzyme-catalyzed CO2 hydration. This study examined the effects of bovine carbonic anhydrase (BCA) and CO2-rich gas streams on the carbonation rate of brucite [Mg(OH)2], a highly reactive mineral. Alkaline brucite slurries were amended with BCA and supplied with 10% CO2 gas while aqueous chemistry and solids were monitored throughout the experiments (hours to days). In comparison to controls, brucite carbonation using BCA was accelerated by up to 240%. Nesquehonite [MgCO3·3H2O] precipitation limited the accumulation of hydrated CO2 species, apparently preventing BCA from catalyzing the dehydration reaction. Geochemical models reproduce observed reaction progress in all experiments, revealing a linear correlation between CO2 uptake and carbonation rate. Data demonstrates that carbonation in BCA-amended reactors remained limited by CO2 supply, implying further acceleration is possible.

Nanobiocatalysis: Nanostructured materials – a minireview

The field of nanobiocatalysis has experienced a rapid growth due to recent advances in nanotechnology. However, biocatalytic processes are often limited by the lack of stability of the enzymes and their short lifetime. Therefore, immobilization is key to the successful implementation of industrial processes based on enzymes. Immobilization of enzymes on functionalized nanostructured materials could give higher stability to nanobiocatalysts while maintaining free enzyme activity and easy recyclability under various conditions. This review will discuss recent developments in nanobiocatalysis to improve the stability of the enzyme using various nanostructured materials such as mesoporous materials, nanofibers, nanoparticles, nanotubes, and individual nanoparticles enzymes. Also, this review summarizes the recent evolution of nanostructured biocatalysts with an emphasis on those formed with polymers. Based on the synthetic procedures used, established methods fall into two important categories: “grafting onto” and “grafting from”. The fundamentals of each method in enhancing enzyme stability and the use of these new nanobiocatalysts as tools for different applications in different areas are discussed.

Surface Engineering of Polypropylene Membranes with Carbonic Anhydrase-Loaded Mesoporous Silica Nanoparticles for Improved Carbon Dioxide Hydration

Carbonic anhydrase (CA) is a native enzyme that facilitates the hydration of carbon dioxide into bicarbonate ions. This study reports the fabrication of thin films of active CA enzyme onto a porous membrane substrate using layer-by-layer (LbL) assembly. Deposition of multilayer films consisting of polyelectrolytes and CA was monitored by quartz crystal microgravimetry, while the enzymatic activity was assayed according to the rates of p-nitrophenylacetate (p-NPA) hydrolysis and CO2 hydration. The fabrication of the films onto a nonporous glass substrate showed CO2 hydration rates of 0.52 ± 0.09 μmol cm(-2) min(-1) per layer of bovine CA and 2.6 ± 0.7 μmol cm(-2) min(-1) per layer of a thermostable microbial CA. The fabrication of a multilayer film containing the microbial CA on a porous polypropylene membrane increased the hydration rate to 5.3 ± 0.8 μmol cm(-2) min(-1) per layer of microbial CA. The addition of mesoporous silica nanoparticles as a film layer prior to enzyme adsorption was found to increase the activity on the polypropylene membranes even further to a rate of 19 ± 4 μmol cm(-2) min(-1) per layer of microbial CA. The LbL treatment of these membranes increased the mass transfer resistance of the membrane but decreased the likelihood of membrane pore wetting. These results have potential application in the absorption of carbon dioxide from combustion flue gases into aqueous solvents using gas-liquid membrane contactors.

Carbonic anhydrase-mimetic bolaamphiphile self-assembly for CO2 hydration and sequestration

A biomimetic catalyst was prepared through the self-assembly of a bolaamphiphilic molecule with histidine moieties for the sequestration of carbon dioxide. The histidyl bolaamphiphilic molecule bis(N-α-amidohistidine)-1,7-heptane dicarboxylate has been synthesized and self-assembled to produce analogues of the active sites of carbonic anhydrase (CA) after association with Zn(2+) ions. Spectroscopic analysis demonstrated the coordination of the Zn(2+) ions with histidine imidazole moieties, which is the core conformation of CA active sites. The Zn-associated self-assembly worked as a CA-mimetic catalyst that shows catalytic activity for CO2 hydration. Evaluation of the kinetics of using para-nitrophenylacetate revealed that the kinetic parameters of the CA-mimetic catalyst were maximized at the optimal Zn concentration and that excess Zn ions resulted in deteriorated catalytic activity. The performance of the CA-mimetic catalyst was enhanced by changing the pH value and temperature of the reaction, which implies that the hydrolysis of the substrate is the rate-determining step. The catalyst-assisted sequestration of CO2 was demonstrated by CaCO3 precipitation upon the addition of Ca(2+) ions. This study offers an easy way to prepare enzyme analogues for CO2 sequestration through the self-assembly of bolaamphiphile molecules with designer biochemical moieties.

Electropolymerized carbonic anhydrase immobilization for carbon dioxide capture

Biomimetic carbonation carried out with carbonic anhydrase (CA) in CO2-absorbing solutions, such as methyldiethanolamine (MDEA), is one approach that has been developed to accelerate the capture of CO2. However, there are several practical issues, such as high cost and limited enzyme stability, that need to be overcome. In this study, the capacity of CA immobilization on a porous solid support was studied to improve the instability in the tertiary amine solvent. We have shown that a 63% porosity macroporous carbon foam support makes separation and reuse facile and allows for an efficient supply and presentation of CO2 to an aqueous solvent and the enzyme catalytic center. These enzymatic supports conserved 40% of their initial activity after 42 days at 70 °C in an amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical barrier associated with the recovery of the biocatalyst after operation, and most of all, these electropolymerized enzymatic supports have shown a remarkable increase of thermal stability in an amine-based CO2 sequestration solvent.

Carbonic anhydrases in industrial applications

Carbonic anhydrases (CAs) catalyze a fundamental reaction: the reversible hydration and dehydration of carbon dioxide (CO2) and bicarbonate ([Formula: see text]), respectively. Current methods for CO2 capture and sequestration are harsh, expensive, and require prohibitively large energy inputs, effectively negating the purpose of removing CO2 from the atmosphere. Due to CA's activity on CO2 there is increasing interest in using CAs for industrial applications such as carbon sequestration and biofuel production. A lot of work in the last decade has focused on immobilizing CA onto various supports for incorporation into CO2 scrubbing applications or devices. Although the proof of principle has been validated, current CAs being tested do not withstand the harsh industrial conditions. The advent of large-scale genome sequencing projects has resulted in several emerging efforts seeking out novel CAs from a variety of microorganisms, including bacteria, micro-, and macro-algae. CAs are also being investigated for their use in medical applications, such drug delivery systems and artificial lungs. This review also looks at possible downstream uses of captured and sequestered CO2, from using it to enhance oil recovery to incorporating it into useful and financially viable products.

Carbonic anhydrase promotes the absorption rate of CO2 in post-combustion processes

The rate of carbon dioxide (CO2) absorption by monoethanol amine (MEA), diethanol amine (DEA), N-methyl-2,2'-iminodiethanol (MDEA), and 2-amino-2-methyl 1-propanol (AMP) solutions was found to be enhanced by the addition of bovine carbonic anhydrase (CA), has been investigated using a vapor-liquid equilibrium (VLE) device. The enthalpy (-ΔHabs) of CO2 absorption and the absorption capacities of aqueous amines were measured in the presence and/or absence of CA enzyme via differential reaction calorimeter (DRC). The reaction temperature (ΔT) under adiabatic conditions was determined based on the DRC analysis. Bicarbonate and carbamate species formation mechanisms were elucidated by (1)H and (13)C NMR spectral analysis. The overall CO2 absorption rate (flux) and rate constant (kapp) followed the order MEA > DEA > AMP > MDEA in the absence or presence of CA. Hydration of CO2 by MDEA in the presence of CA directly produced bicarbonate, whereas AMP produced unstable carbamate intermediate, then underwent hydrolytic reaction and converted to bicarbonate. The MDEA > AMP > DEA > MEA reverse ordering of the enhanced CO2 flux and kapp in the presence of CA was due to bicarbonate formation by the tertiary and sterically hindered amines. Thus, CA increased the rate of CO2 absorption by MDEA by a factor of 3 relative to the rate of absorption by MDEA alone. The thermal effects suggested that CA yielded a higher activity at 40 °C.

Enzymatic Carbon Dioxide Capture

In the past decade, the capture of anthropic carbonic dioxide and its storage or transformation have emerged as major tasks to achieve, in order to control the increasing atmospheric temperature of our planet. One possibility rests on the use of carbonic anhydrase enzymes, which have been long known to accelerate the hydration of neutral aqueous CO2 molecules to ionic bicarbonate species. In this paper, the principle underlying the use of these enzymes is summarized. Their main characteristics, including their structure and catalysis kinetics, are presented. A special section is next devoted to the main types of CO2 capture reactors under development, to possibly use these enzymes industrially. Finally, the possible application of carbonic anhydrases to directly store the captured CO2 as inert solid carbonates deserves a review presented in a final section.

Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin

Porous silicon (PSi) is widely used in biological experiments, owing to its biocompatibility and well-established fabrication methods that allow tailoring its surface. Nevertheless, there are some unresolved issues such as deciding whether the stabilization of PSi is necessary for its biological applications and evaluating the effects of PSi stabilization on the surface biofunctionalization with proteins. In this work we demonstrate that non-stabilized PSi is prone to detachment owing to the stress induced upon biomolecular adsorption. Biofunctionalized non-stabilized PSi loses the interference properties characteristic of a thin film, and groove-like structures resulting from a final layer collapse were observed by scanning electron microscopy. Likewise, direct PSi derivatization with 3-aminopropyl-triethoxysilane (APTS) does not stabilize PSi against immunoglobulin biofunctionalization. To overcome this problem, we developed a simple chemical process of stabilizing PSi (CoxPSi) for biological applications, which has several advantages over thermal stabilization (ToxPSi). The process consists of chemical oxidation in H2O2, surface derivatization with APTS and a curing step at 120 °C. This process offers integral homogeneous PSi morphology, hydrophilic surface termination (contact angle θ = 26°) and highly efficient derivatized and biofunctionalized PSi surfaces (six times more efficient than ToxPSi). All these features are highly desirable for biological applications, such as biosensing, where our results can be used for the design and optimization of the biomolecular immobilization cascade on PSi surfaces.