Glyoxal Acid-Free (GAF)

Glyoxal Acid-Free (GAF)


Our project proposes the replacement of Formalin with GAF, a non-toxic and non-cancerogenic fixative solution, with equivalent (if not better) histological efficacy, responding to the need to protect the health of workers involved and, at the same time, the health of patients.

Gliossale Acid Free


fissativo istologico a base di gliossale

Furthermore, the project is aimed at protecting the environment by reducing the use and disposal of a toxic product such as Formaldehyde. In fact, Formaldehyde’s carcinogenic and toxic vapours absorbed by the hoods are partially released into air, while the disposal of liquid Formalin is complex and expensive. It is desirable that the amount of toxic waste released in the environment, although somehow controlled, be strongly reduced.

Therefore, the replacement of Formalin is recommended for both environmental and health reasons. Furthermore, they are now normatively mandated by EU legislation. Glyoxal (a di-aldehyde similar to Formaldehyde) is not volatile nor toxic. When deprived of troublesome acids, Glyoxal Acid-Free (GAF) represents a safe histological fixative and a Formalin alternative, providing results as good (or even better) than Formalin. This has been proved by histological, immuno-histochemical and molecular analyses.


GAF Safety Datasheet

GAF Technical Datasheet


Tissue fixation, leading to preservation of structural components by fixation and permeabilization of cells and tissues, plays a critical role in histopathological diagnosis.

The fixative of choice is still represented by Formalin (a water solution of Formaldehyde).

This reagent is toxic and cancerogenic, but is still used worldwide in the lack of alternative fixative solutions guaranteeing similar results.

fissazione medicina
istologia dei tessuti

GAF (Glyoxal, acid free) fixative solution is an innovative reagent that allows optimal tissue fixation at the structural and molecular level, combined with the absence of toxicity and carcinogenic activity.

The validation of GAF fixative, as compared to Formalin, was conducted on parallel samples, obtained with core needles or punch devices from surgical specimens and fixed alternatively in Formalin and in GAF.

The first Validation trial was conducted in December 2017 at the San Giovanni Battista Hospital of Turin.


Glyoxal solution in Endoscopic Biopsies Project (Prot. N. 111243 of 6.11.17). COMPLETED

The clinical Trial performed at the Molinette Hospital (Turin) was aimed to validate the histopathological use of GAF as a fixative solution for small endoscopic biopsies (300 biopsies).

Results: The team involved in the validation study expressed a highly favourable opinion regarding both the sampling in endoscopy and the histo-pathological diagnostic aspects, without finding any problems or negative features involving the routinely use of the GAF fixative.

Performance evaluation of Glyoxal Acid Free (GAF) used as histological fixative in comparison with Formalin. An open label, comparative non inferiority study. COMPLETED

A controlled trial (CRO: 1MED, Lugano, CH), carried out in three European Countries (Italy, Spain and UK), evaluated the overall values and merits of GAF as a fixative solution compared to Formalin. The study based on a large number of small oncological biopsies. Samples from large surgical specimens have been randomly labelled, fixed in parallel in GAF or in Formalin, and processed for the routinely diagnostic tests. The slides have been scanned and scored in parallel by a central reviewer in blind. The results of the tests carried out acted as a European-level technical validation of our GAF product and were published in the Journal Virchows Archiv.


A study on alternative protocols of tissue fixation demonstrated that GAF® radically improves the interpretation of clinical comprehensive genomic profiling. GAF® stood out as the only non-carcinogenic option that encompasses the artifacts and low DNA preservation observed in formalin fixation.

Evaluation of GAF for veterinarian application. COMPLETED

The trial is aimed at studying the efficacy of GAF for veterinarian use (on oncological and non-oncological surgical specimens), and is current ongoing in collaboration with the University of Padova and Perugia.


Validation of GAF fixative, as compared to Formalin, is conducted through national and international Trials evaluating results of parallel samples, obtained from surgical specimens, fixed alternatively in Formalin and in GAF. The first Validation trial was conducted at the San Giovanni Battista Hospital of Turin, Italy. The results confirmed the feasibility and validity of GAF fixation as alternative to Formalin fixation.

Representative slides (10 cases in parallel, fixed either in Formalin or in GAF) of this first Trial are shown below.

n. 24230/17 Formalin Fixation – A | CASE 1

n. 24230/17 GAF – B | CASE 2

n. 24748/17 Formalin Fixation – B | CASE 3

n. 24748/17 GAF – A | CASE 4

n. 24837/17 Formalin Fixation – A | CASE 5

n. 24837/17 GAF – B | CASE 6

n. 25462/17 Formalin Fixation - A | CASE 7

n. 25462/17 GAF – B | CASE 8

n. 25921/17 Formalin Fixation – A | CASE 9

n. 25921/17 GAF – B | CASE 10

n. 25936/17 Formalin Fixation – B | CASE 11

n. 25936/17 GAF – A | CASE 12

n. 26021/17 Formalin Fixation – B | CASE 13

n. 26021/17 GAF – A | CASE 14

n. 26315/17 Formalin Fixation – A | CASE 15

n. 26315/17 GAF – B | CASE 16

n. 26422/17 Formalin Fixation – B | CASE 17

n. 26422/17 GAF – A | CASE 18

n. 27004/17 Formalin Fixation – B | CASE 19

n. 27004/17 GAF – A | CASE 20


The research and technology transfer activities have been the subject of in-depth articles available here:

validazione fissativo istologico

ADDAX Biosciences was born as a spin off of the University of Turin, which contribuited with support to the research activity.

bandiera unione europea

Our company has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 8157692.

The project “GAF – Towards a hospital without Formalin” is realized thanks to the co-financing of POR FESR Piemonte 2014-2020, Ob.1 – “Research, technological development and innovation, I.1.b.4.1 “Support for creation and consolidation of innovative start-ups with a high intensity of application and knowledge and research spin-off initiatives”.

The project aims to validate, produce and market GAF, a histological fixative without carcinogenicity, that works as a substitute to Formalin. Achieving the project’s objectives will improve the working conditions of health and research professionals, protecting them from the risk of developing occupational diseases caused by inhaling Formalin vapours.


The information contained in this section is intended exclusively for Healthcare Professionals, in compliance with the Italian legislation, specifically with Art. 21 of the Decreto Legislativo 24 February 1997, n. 46, and the “Guidelines of the Ministry of Health” issued on the 17 February 2010, 28 March 2013 and 20 December 2017. If you intend to access the information, you have to declare and confirm to be a Healthcare Professional by clicking on this disclaimer.